Most brands pick their bottoms fabric backwards.

They find a pair of pants they like, ask for “the same material,” and hope the sample comes back right.

It rarely does because the pants they liked were a 380 GSM loopback terry with a compacted finish, and what they described was “thick cotton.”

Bottoms are less forgiving than tops. A hoodie hangs off the shoulders and forgives a lot.

Pants sit on the waist, take the full weight of the leg, get sat on, get knelt in, get dragged over the heel, and get stretched at the seat every time the wearer bends.

Fabric choice on bottoms shows up as fit failure, not just hand feel.

This guide covers the full bottoms fabric landscape in one place: the five families, what each is genuinely good at, the weight ranges that actually work, the blend and stretch decisions underneath them, and how to write the choice into a tech pack so the factory builds what you meant.

It is written from the production side. I run the manufacturing floor at Gibben Clothing in Sialkot, and most of what follows comes from garments that came back wrong before they came back right.

Read it start to finish if you are choosing a first-bottoms style. Jump to a chapter if you already know the family and need the numbers.

THE 30-SECOND ANSWER

Joggers and sweatpants: French terry at 300–380 GSM, or brushed fleece at 320-420 GSM if you want warmth. Cargos and structured pants: cotton twill, 8-11 oz. Utility and techwear: ripstop or canvas.

Shell pants, parachute pants, and track pants: nylon or a technical poly. Everything after this is about getting the weight, blend, and finish right, which is where the money is actually made or lost.

01

Fleece and French terry on a leg:

Terry and fleece are the same cloth at two stages of finishing; fleece is terry with the inside loops brushed open.

We cover that family in full in our streetwear fabric guide. This chapter only covers what changes when you put that cloth on a leg instead of a torso.

Three things change, and all three catch brands out.

Drape works harder. A trouser leg is a narrow tube with a long seam, so the fabric has to fall cleanly over the thigh and hold a taper.

Terry keeps its loops intact, stays denser, and falls closer to the leg. Fleece has air brushed into it, so it reads fuller and is good on slouchy wide sweatpants and puffy on a tailored taper.

Bulk lands on seams. On a hoodie, the heavy joins are at the shoulder and hood. On a pant, they are at the crotch junction and the cuff, where four to six layers meet.

The same 420 GSM fleece that feels right in a hoodie can give you a hard, lumpy crotch seam in a jogger.

Heat is higher. A pant wraps the whole leg, so it sits against more skin than a hoodie does.

A fleece weight that reads “cosy” on top reads “hot” on the bottom. For year-round bottoms, go one step lighter than the hoodie weight, or drop the brushing.

KNIT BOTTOMS: WORKING WEIGHTS

Sweat short French terry, 260-300 GSM
Year-round jogger French terry, 300-340 GSM, the premium sweet spot
Standard sweatpants Light-brushed fleece, 340–400 GSM
Heavyweight sweatpants Fleece, 400-450 GSM, except bulk at the crotch and cuff
Rib for cuff and waistband 320-380 GSM 2×2 rib, 3-5% elastane; the underspecified rib is why tapers collapse

Shrinkage shows up as a short inseam:

Untreated cotton knits shrink in length. On a hoodie that costs you body length, you can live with it.

On a 105 cm inseam, it turns a full-length jogger into an ankle-grazer, and length is the one measurement customers notice immediately.

Specify one of two fixes in writing. Either compacted/pre-shrunk fabric with a stated maximum residual shrinkage of 3% or less in both directions, or a shrinkage allowance built into the pattern, which means the garment only measures correctly after washing.

Then test on the bulk fabric, not the swatch card: a marked 50 × 50 cm square through three domestic wash cycles]], with length and width movement recorded separately.

Spirality: the leg that twists

This one is specific to bottoms, and it catches almost every new brand.

Weeks after delivery, customers report that the side seam has rotated toward the front of the leg.

Nothing was sewn wrong. The fabric is untwisting.

Knits made on a circular machine carry residual twist from the yarn.

If the fabric is finished in tube form and not corrected, that twist releases in the first wash and drags the seam around the leg.

A long, narrow trouser seam makes the rotation obvious in a way a torso never does.

The fix is a fabric decision, not a sewing decision.

Specify open-width finished fabric, ask for a torque or spirality figure, aim for under 5%, and prefer yarn balanced for knitting.

Ask the mill directly. A mill that has the number ready is a mill that measures it.

FROM THE FLOOR

We had a client reject a full run of 600 joggers because the side seams had walked forward about 4 cm at the hem after washing.

The stitching was clean. The pattern was correct. The fabric was tubular-finished terry with untreated twist.

Every knit bottoms order we take now gets a spiral line on the fabric approval sheet before we cut.

CHAPTER 1 IN ONE LINE

Go one step lighter than your hoodie weight, then spec compacting, residual shrinkage, and spirality those three decide whether a knit bottom survives, not softness.

02

Cotton twill and chino: the utility base:

Twill is where bottoms stop being knitwear and start being tailoring.

It is a woven fabric with a diagonal rib line you can see running across a pair of chinos if you hold them to the light.

That diagonal comes from the weave: each weft thread passes over two or more warp threads, then under one, stepping over by one each row.

That structure gives twill three properties knits cannot match: it holds a shape, it resists abrasion, and it takes a crease.

Which is why every cargo pant, work pant, chino, and carpenter pant in streetwear is built on it.

Reading a twill spec:

Twill is usually sold by ounce weight per square yard, not GSM, a hangover from workwear.

The conversion is fixed: 1 oz/yd² = 33.9 g/m². So an 8 oz twill is roughly 271 GSM, and a 12 oz is roughly 407 GSM.

You will also see a weave ratio like 3/1 or 2/1. In a 3/1 twill, the weft goes over three warp yarns and under one, producing a strong diagonal, a smoother face, and a denser fabric. 2/1 is lighter and softer. For streetwear bottoms, 3/1 is the workhorse.

COTTON TWILL: WORKING SPEC

Structure Woven, diagonal rib; 2/1 or 3/1 the common ratios
Useful weight 7-12 oz (240-410 GSM) for bottoms
Light chino 7-8 oz summer chinos, relaxed pleated trousers, lighter drape
Standard cargo 8-10 oz is the default for cargo pants and work pants
Heavy utility 10-12 oz stiff, boxy, holds a wide leg; breaks in over months
Common composition 100% cotton; 97/3 cotton-elastane; 65/35 poly-cotton for workwear durability
Watch for Seat and inner-thigh abrasion, crocking on dark dyes, torque on cheap constructions
Our typical range 8 oz, 10 oz and 12 oz cotton twill; 97/3 stretch twill on request



Why does weight change the silhouette, not just the feel?

On a knit jogger, weight mostly changes warmth. On twill, weight changes the garment’s shape.

A 7 oz twill drapes and collapses around the leg. A 12 oz twill stands away from it; that is what makes a wide-leg carpenter pant look architectural instead of saggy.

So work backwards from the silhouette:

  • Wide leg, boxy, structured: 10-12 oz. The fabric holds the leg opening out.
  • Relaxed straight, everyday cargo: 8-10 oz. Enough body to look intentional, light enough to wear all day.
  • Tapered, soft, chino-adjacent: 7-8 oz, often with 2-3% elastane.
A cargo pant that looks limp in production is usually a pattern designed for a heavier twill than the one sourced.

Finishes matter more on twill than anywhere else:

Raw twill off the roll is stiff, slightly shiny, and unfriendly. Almost every good pair of cargos has been through at least one finishing process:

Enzyme wash:

Cellulase enzymes eat the surface fabrics, which softens the hand and gives a slightly worn look.

It also removes a little weight, so account for it in your weight spec; an enzyme-washed 10 oz behaves closer to a 9 oz.

Peaching/sueding:

A very light abrasive brush that raises a fine nap. Gives a matte, almost suede-like surface.

It is what turns a plain cotton twill into something that reads premium in a photo.

Garment dye

Dyeing after sewing, which gives the uneven, lived-in color depth that sells well in streetwear.

It also makes size consistency harder, because every garment shrinks in the dye bath.

If you go garment-dyed, expect looser tolerances and build that into your grading. Our garment-dye tolerance on the waist is ±1.5 cm vs ±1 cm on piece-dyed.

Silicone softener:

Cheap, fast, and it makes the sample feel fantastic. It also washes out.

If a supplier’s twill sample feels dramatically softer than every other twill you have handled at that weight, wash it once before you decide.

FROM THE FLOOR

The most common twill complaint we see post-delivery is not durability; it is color rubbing off onto light furniture and shoes.

That is crocking, and it happens when dark reactive or sulphur dyes are not fully washed off after dyeing.

Ask for a crocking test result (dry and wet rub) on dark twills before bulk. On our dark indigo and black twills, we require a minimum of grade 4 dry / grade 3 wet.

Twill’s real weak point: the seat and inner thigh

Twill resists abrasion well in general, but on bottoms the load is concentrated.

The inner thigh rubs against itself with every step, and the seat takes compression every time the wearer sits.

On a slim fit in a lighter twill, that is where blowouts happen first.

Three ways to buy insurance:

  1. Go up in weight where the fit is slim. A slim 8 oz will outlast a slim 7 oz by a lot more than the 1 oz suggests.
  2. Add polyester. A 65/35 poly-cotton twill takes more abrasion than 100% cotton dramatically at the same weight, which is why workwear has used it for decades.
  3. Reinforce the construction. Gusseted crotch, bar tacks at pocket corners and fly, and a felled or double-needle inseam. Fabric is only half the answer.

Cargo construction pocket geometry, bellow depth, and placket and flap detailing, and where the reinforcement actually goes, are separate subjects. We cover it in our guide to building cargo pants and utility bottoms.

CHAPTER 2 IN ONE LINE

Pick the weight of the twill from the silhouette you want, not the season, and then decide the finish and the crocking standard, because those two are what customers actually notice.

03

Ripstop and canvas: rugged builds:

These two get grouped because they answer the same brief: make it tough by opposite means.

Canvas is tough because it is heavy. Ripstop is tough because it is clever.

Ripstop: the grid does the work

Ripstop is a plain or twill weave with thicker reinforcement yarns woven in at regular intervals, usually every 5-8 mm, in both directions.

You can see the faint grid on the surface. If the fabric gets punctured, the tear runs until it hits a reinforcement yarn and stops there. Instead of a 20 cm rip, you get a 6 mm hole.

That is a genuinely different durability model. Ripstop is not necessarily more abrasion-resistant than canvas; it is more damage-tolerant.

For a cargo pant that will be worn near tools, bike chains, gravel, and fence wire, damage tolerance is the property that matters.

RIPSTOP: WORKING SPEC

Structure Plain or twill weave with a reinforcement grid every 5-8 mm
Cotton ripstop 5-8 oz (170-270 GSM) matte, breathable, takes dye and washes well
Poly-cotton ripstop 65/35 or 50/50 the military and workwear standard; dries fast, holds color
Nylon ripstop Sold in denier: 20D-70D for shell and packable, 210D+ for hard-wearing panels
Best for Cargo pants, utility shorts, techwear panels, and packable and travel bottoms
Watch for Grid visibility on light colors, stiffness on heavier deniers, seam slippage on very fine nylons
Our typical range 6 oz cotton ripstop, 65/35 poly-cotton ripstop, 70D, and 210D nylon ripstop



Denier, briefly:

Denier measures the linear density of a filament yarn in grams per 9,000 meters.

Higher denier means thicker yarn, so 210D nylon is much more substantial than 40D.

It is a yarn measurement, not a fabric weight, which is why two 70D fabrics can feel different depending on weave density.

When you spec nylon, give denier and fabric weight in GSM.

Canvas: mass as a strategy

Canvas duck canvas specifically is a plain weave using heavy, often plied yarns.

There is no trick to it. It is dense, rigid, abrasion-resistant cotton that starts stiff and softens over months of wear into something with real character.

This is the fabric behind carpenter pants, painter pants, and the heavyweight utility silhouette.

It is also the one most likely to disappoint brands that do not warn their customers, because a new 12 oz canvas pant is genuinely uncomfortable for the first few wears.

COTTON DUCK CANVAS: WORKING SPEC
Structure Plain weave, heavy or plied yarns, very dense
Useful weight 8-14 oz (270-475 GSM) for bottoms
Sweet spot 10-12 oz tough enough to read as workwear, wearable from day one
Best for Carpenter and painter pants, wide-leg utility, hard-wearing shorts
Watch for Needle heat and breakage in sewing, bulky seam intersections, long break-in period, heavy garment weight for shipping
Our typical range 10 oz and 12 oz duck canvas, raw and enzyme-washed

Canvas costs more to sew than to buy:

This is the part brands miss when comparing quotes. Heavy canvas slows a line down.

Seam intersections at the crotch can be eight or ten layers thick.

You need heavier needles, stronger thread, more machine maintenance, and operators who can hold quality at that thickness.

Needle breakage and skipped stitches go up.

So when a 12 oz canvas pant quotes higher than a 10 oz twill pant, the fabric price difference is usually the smaller half of the gap.

On our floor, a heavy canvas bottom typically runs 15-20% more SAM (standard allowed minutes) than the same pattern in mid-weight twill.

Choosing between them:

If the priority is… Choose Because
Surviving snags and punctures Ripstop The grid stops a tear from running
Surviving constant rubbing Canvas Mass and yarn density resist abrasion
Lightweight and packability Ripstop Strength-to-weight is far better
A structured, standing silhouette Canvas Rigidity holds the leg shape
Fast drying and color retention Poly-cotton ripstop Synthetic content sheds water and holds dye
Character that improves with age Canvas Cotton softens and fades where the body moves

How is durability actually measured?

If a supplier tells you a fabric is “very durable,” ask what test that claim comes from.

The standard method for abrasion resistance is the Martindale test, published as ASTM D4966 and, in Europe, as ISO 12947.

A circular sample is rubbed against an abradant under load, and the cycles are counted until breakdown or a defined appearance change.

Two cautions before you use those numbers as a buying rule.

First, ASTM itself notes the between-laboratory precision of the test is poor and that it is not considered satisfactory for acceptance testing of commercial shipments, so treat a cycle count as a comparison between fabrics tested the same way, not a guarantee.

Second, most published Martindale benchmarks come from upholstery, not apparel, so a number that sounds impressive on a sofa spec sheet does not translate directly to a pant.

The practical version: get Martindale results from the same lab on the two or three fabrics you are choosing between, and use them to rank, not to certify.

CHAPTER 3 IN ONE LINE

Ripstop buys damage tolerance at low weight; canvas buys abrasion resistance at high weight, and canvas also buys a higher sewing cost that should be in your quote from the start.

04

Nylon and technical fabrics: shell, parachute, and track pants

This is the fastest-moving corner of streetwear bottoms.

Parachute pants, cargo shells, crinkle nylon track pants, and wind pants with a full side zip all of them are built on synthetic woven fabrics that behave nothing like cotton on the cutting table.

They are also where most first-time brands get burned, because a nylon pant looks simple and is not.

The four fabrics that cover 90% of technical bottoms:

Nylon taslan:

Air-textured nylon with a slightly crisp hand and a soft matte surface. It is the default parachute-pant fabric: light, quick-drying, holds a voluminous shape without looking cheap, and takes a DWR finish well. Typical weights sit around 90-140 GSM.

Crinkle nylon:

Nylon that has been mechanically crushed and heat-set so the wrinkles are permanent. Gives that papery, rustling, track-pant look. Important: the crinkle is set by heat, so pressing it flat at any point in production destroys the effect. Your factory needs to know that before the first sample, and finishing must be planned around it.

Polyester taffeta and micro-poly:

Cheaper than nylon, slightly shinier, less abrasion-resistant, but holds color better in sunlight and costs meaningfully less. Most volume track pants and wind pants are polyester rather than nylon, whatever the hangtag implies.

Nylon ripstop:

Covered in Chapter 3. In bottoms, it shows up either as the whole garment for packable and travel pants or as reinforcement panels at the knee and seat on techwear builds.

TECHNICAL WOVENS: WORKING SPEC
Measured in Denier (yarn) plus GSM (fabric). Give both.
Light shell/parachute 20D-70D, roughly 70-130 GSM
Everyday track/wind pants 70D-150D, roughly 110-180 GSM
Hard-wearing cargo shell 210D+, often with a coating or a heavier weave
Common finishes DWR, calendaring, PU or acrylic coating, matte or high-shine
Lining Mesh or poly taffeta decides early; it changes the pattern
Watch for Seam slippage, needle holes, static cling, and color matching between fabric and trims

Three production problems specific to nylon bottoms:

1. Needle holes are permanent:

On cotton, a misplaced seam can be unpicked, and the fabric mostly closes up. On a tightly woven nylon, it does not; the needle has displaced filament yarns, and the holes stay visible.

That means fewer chances to correct, a higher skill requirement on the line, and a real need for finer needles and correct stitch density.

We run 70/10 or 75/11 ballpoint-free sharps at 10-12 stitches per inch on light nylon shells.

2. Seam slippage at stress points:

Slippery filament yarns can slide apart under load, opening a gap along the seam even though the stitching is intact.

It shows up at the seat, the crotch, and the pocket openings, exactly where a pant takes load.

Fixes are construction-side: French seams or bound seams instead of plain overlock, wider seam allowance, and bar tacks or reinforcement tape at the crotch junction.

3. The hand you feel is often a coating:

Many nylon and poly fabrics get a PU or acrylic back coating to add body, block wind, or change the surface.

Coatings are also the main reason two fabrics with identical composition on paper feel completely different.

Always approve a physical swatch, and ask whether the hand comes from the weave or from a finish that may wear off.

FROM THE FLOOR

The most common nylon sample rejection we see is not fabric; it is trim mismatch.

A matte nylon shell with a glossy zip tape, or a warm-black fabric against a cool-black drawcord, looks wrong immediately in photos, even though every component passed on its own.

Approve fabric and trims together, under the same light, in the same submission.

Water repellency and the PFAS problem:

Most shell bottoms carry a DWR (durable water repellent) finish. Historically, that finish used PFAS chemistry, and if you are selling into the United States,, that is now a compliance question rather than a preference.

California’s AB 1817 bans intentionally added PFAS in most textiles and apparel, with the first phase effective 1 January 2025 and a total organic fluorine limit of 100 ppm that drops to 50 ppm in January 2027.

New York’s parallel law (S.1322/A.994) also took effect in January 2025 and applies to apparel broadly, with a narrow, time-limited exemption for severe-wet-condition outdoor gear.

The practical consequence for a streetwear brand: a water-repellent cargo or shell pant sold into those states needs PFAS-free DWR, and the manufacturer has to be able to certify it.

Ask your supplier for a written compliance certificate and a test report, not a verbal assurance.

Gibben supplies a PFAS-free DWR option with mill test reports on request.

PFAS-free DWR performs slightly differently, and it is worth knowing the trade-off in advance:

It typically sheds water well when new, but it needs reactivation with heat more often and tends to lose performance faster against oil-based stains.

For a streetwear shell pant, that is rarely a problem. For a product you market as weatherproof, test it properly.

CHAPTER 4 IN ONE LINE

Technical bottoms are a construction problem disguised as a fabric problem pick the fabric for the silhouette, then budget for finer needles, slip-resistant seams, matched trims, and a compliant DWR.

05

Choosing a blend for a garment that takes a load:

The general fabric argument for how cotton, polyester, and blends differ in hand, breathability, and price is covered in our streetwear fabric guide.

Bottoms change the weighting of that argument, because a pant is under mechanical load in a way a top never is.

Three load points decide the blend.

1. The knee and the seat bag are out:

Every time the wearer sits or crouches, the fabric at the knee and seat is stretched and held there. Cotton has poor elastic recovery, so it stays stretched.

That is why 100% cotton joggers develop knee bubbles and a flattened seat within weeks, and why the same fabric on a hoodie shows nothing.

Polyester recovers. Twenty percent of it in a knit bottom is enough to change the outcome noticeably.

This is the single strongest argument for a blend on bottoms, and it has nothing to do with cost.

20% polyester in a jogger is not a compromise on quality. It is what stops the knee from bagging out.

2. The inner thigh rubs against itself:

On wovens, the failure is abrasion, concentrated at the inner thigh and the seat.

A 65/35 poly-cotton twill takes substantially more abrasion than 100% cotton at the same weight, which is why workwear has used that blend for decades and why it is the right call on any bottom aimed at daily or physical wear.

If the brand positioning demands 100% cotton, buy the durability back somewhere else: go up a weight, add a gusseted crotch, bar tack the pocket corners and fly, and use a felled or double-needle inseam.

3. Length shrinkage is unforgiving:

Covered in Chapter 1, but it belongs in the blend decision too.

Polyester content reduces shrinkage roughly in proportion to its share, which is why a 60/40 or 50/50 is the honest choice for a value program where you cannot afford tight finishing control.

If the bottom has to… Blend Why
Hold its shape through daily wear 80/20 cotton-poly knit Cotton hand, enough recovery to stop knee bagging
Hit a volume price point 60/40 or 50/50 knit Dimensionally stable, cheaper, less soft
Survive physical or workwear use 65/35 poly-cotton twill Big jump in abrasion resistance at the same weight
Read premium and age visibly 100% cotton twill or canvas Fades and softens where the body moves; accept lower recovery
Move with the wearer on a slim fit 97/3 cotton-elastane See Chapter 6 spec recovery, not just stretch
Dries fast and holds color outdoors 100% nylon or polyester Shell, track, and parachute builds

A note on recycled polyester claims:

Recycled polyester performs close to virgin for streetwear use, and it is easy to source.

Two things to keep straight before you print anything. “Recycled” usually means bottle-derived, not textile-derived; that matters if a buyer asks about circularity.

And any recycled-content claim on a hangtag should be traceable to a chain-of-custody certificate such as GRS or RCS, because unverifiable environmental claims now attract regulatory attention in both the EU and the US. No transaction certificate, no claim.

Cost: the two fabrics move on different markets

Cotton is an agricultural commodity benchmarked by the Cotlook A Index. Through 2026, it moved a long way:

The index sat around 74 US cents per pound in late February 2026 and was quoted near 86-87 cents by mid-June.

Polyester staple is a petrochemical product priced off crude oil and PTA. Over the same period, PTA spot prices rose sharply while producers cut operating rates, pushing polyester staple up with it.

The numbers will be stale by the time you read this. The behavior will not. Cotton-rich programs carry crop and weather risk; poly-rich programs carry energy-price risk.

If you are planning a year of repeat production on one core bottom, ask your manufacturer to quote fabric separately from making charges so you can see which side of the bill is moving.

FROM THE FLOOR

Brands often ask us to hold a price for twelve months on a cotton-heavy style. We can hold making charges. We cannot hold yarn.

The honest structure is a fixed CM (cut-and-make) rate plus fabric at cost, reviewed for each order. It looks less tidy on a spreadsheet, but it stops both sides from arguing when the crop moves.

CHAPTER 5 IN ONE LINE

On bottoms the blend is a recovery and abrasion decision before it is a hand-feel decision: 80/20 on knits, 65/35 on working twill, and 100% cotton only when you are buying the way it ages.

06

Adding stretch for movement:

Bottoms take more mechanical stress than any other garment category.

Sitting, squatting, climbing stairs, and crouching all demand elongation at the knee, seat, and crotch.

On a woven fabric with no stretch, that elongation has to come from the pattern, extra ease, a gusset, or an articulated knee, or it does not come at all.

Stretch is how most brands solve it. There are two kinds, and they are not interchangeable.

Mechanical stretch vs. elastane stretch:

Mechanical stretch:

Comes from yarn and weave construction: textured filament yarns, a looser sett, or a stretch weave with no elastomeric fabric at all.

Gives a modest amount of give, usually under 10%. Advantages: no elastane to degrade, no recovery loss over time, no heat-setting constraints. Common in technical nylon bottoms.

Elastane stretch:

Elastane (spandex, Lycra) is blended into the yarn or added as a covered core.

Gives real elongation of of 15% to 40%+ depending on percentage and construction, plus genuine recovery, which is the part that actually matters.

ELASTANE: HOW MUCH TO SPEC

1-2% Comfort stretch. Barely perceptible; it mostly prevents the fabric from feeling locked. Good on a relaxed twill.
2-3% The standard for stretch twill cargos and chinos. Noticeable give, no change to the fabric’s look.
3-5% Active range. Slim fits, performance-leaning bottoms, anything worn for movement.
5%+ Rarely right for streetwear bottoms. Starts reading as activewear and raises recovery risk.
Knit bottoms Often need no elastane at all; the knit structure already stretches. Add 2-3% only in ribbed cuffs and waistbands.

Recovery is the spec that matters, not stretch:

Everyone asks for a stretch. Almost nobody asks for recovery.

Then the garment comes back with baggy knees after a week, and everyone is surprised.

Stretch is how far the fabric goes. Recovery is how completely it comes back.

A cheap elastane at 3% can give a great sample and poor recovery, which reads to the customer as a pant that “loses its shape.”

Ask for growth after extension as a tested number, typically elongated to a set percentage, held, released, and then measured for residual growth.

Anything over 5% residual growth on the bottom fabric will show at the knee.

Elastane changes how the garment must be handled:

  • Heat is the enemy. Elastane degrades at high temperatures. Pressing, curing screen prints, and heat transfers all need controlled temperatures. Tell your factory the elastane percentage before decoration is planned, not after.
  • Cutting relaxation. Stretch fabric must be relaxed on the table before cutting, or panels shrink back after cutting, and the pattern goes out of spec. This costs table time, which is why stretch styles carry slightly higher CM rates.
  • Sewing needs the right stitch. A rigid lockstitch on a stretch seam will snap. Stretch seams need a suitable stitch type and thread with some elongation.
  • It complicates recycling and can disqualify a garment from some circularity claims. Worth knowing if sustainability is part of your positioning.

FROM THE FLOOR

When a client tells us, “The sample fits perfectly, but the production pants run small” on a stretch style, it is almost always a relaxation problem with the fabric cut before it had fully relaxed on the table.

We now hold stretch fabric a minimum of 24 hours]] in a relaxed spread before cutting, and it is written into the order sheet rather than left to the cutting floor.

CHAPTER 6 IN ONE LINE

2-3% elastane covers most streetwear bottoms; specify recovery and growth alongside it, and warn the factory early because stretch changes cutting, pressing,, and decoration.

07

Matching fabric to style and GSM:

By this point, you have the families. The remaining question is the one that decides whether the garment looks like your reference image: what weight, in what structure, and for which silhouette?

Two rules before the table.

Rule 1: GSM and oz measure the same thing

GSM is grams per square meter. Ounce weight is ounces per square yard. Knits are usually quoted in GSM, wovens in oz, and 1 oz/yd² = 33.9 GSM.

If a supplier quotes for one unit and your tech pack uses the other, convert it in the tech pack rather than assuming they will.

Rule 2: weight is a range, not a number

Mills work to tolerance. A “320 GSM” fabric will come in somewhere around 320.

Write the tolerance you accept into the spec: ±5% is normal for knits; tighter is possible but costs more.

If you do not state it, you have no basis to reject a light delivery.

The style-to-fabric map:

Silhouette Fabric Weight Composition Key spec note
Tapered jogger French terry 300-340 GSM 80/20 CVC Compacted, open-width, low spirality
Heavyweight sweatpants Brushed fleece 380-450 GSM 100% cotton or 80/20 Single brush for durability; expect bulk at joins
Summer sweat shorts French terry 260-300 GSM 100% cotton Lighter for breathability; check opacity
Relaxed cargo pant Cotton twill 3/1 8-10 oz (270-340 GSM) 100% cotton or 97/3 stretch Enzyme wash by hand; crocking test on darks
Wide-leg carpenter pant Duck canvas 11-12 oz (375-410 GSM) 100% cotton Budget higher SAM; heavy needles
Utility / techwear cargo Ripstop 6-8 oz cotton or 65/35 Cotton or poly-cotton Grid visible on light shades; check on color
Parachute pants Nylon taslan 90-140 GSM 100% nylon Volume comes from pattern, not weight
Track/wind pants Crinkle nylon or poly taffeta 80-130 GSM Nylon or polyester Do not press crinkle; plan lining early
Shell cargo Nylon ripstop 210D+ 100% nylon PFAS-free DWR if selling into CA / NY
Every day, Chino Cotton twill 2/1 7-8 oz (240-270 GSM) 97/3 cotton-elastane Spec recovery, not just stretch
Lounge/set bottom Light terry or tri-blend 240-280 GSM CVC or tri-blend Match the top’s fabric lot for color

 

Three cross-checks people forget when they use a table like this:

  1. Check opacity on light colors. A 260 GSM terry in black is fine. The same fabric in cream can show skin under flash photography. Test the lightest color in your range, not the darkest.
  2. Check the whole outfit weight. If the matching hoodie is 400 GSM fleece and the pant is 300 GSM terry, the set will look mismatched on a rail even though both are correct on their own. Set programs should share the fabric.
  3. Check the cuff and waistband. A great jogger’s body fails if the rib is underspecified. Rib should be heavier than instinct suggests (320-380 GSM 2×2 rib with 3-5% elastane), or the cuff relaxes, and the taper collapses.

If GSM is where your decisions keep getting stuck, our complete GSM guide for apparel breaks down weight ranges across every garment category, with the conversions and tolerances in one place.

CHAPTER 7 IN ONE LINE

Choose weight from the silhouette, state the tolerance, and check opacity, set-matching and rib weight before you approve.

08

The spec fields that only matter on bottoms:

The baseline fabric spec composition and yarn type, construction, target weight with tolerance, finish, shrinkage, rib, and a signed physical swatch are the same for every garment, and we set it out field by field in the streetwear fabric guide. Fill that list for any program.

What follows are the fields that get left blank on bottoms specifically, either because the garment is woven or because a leg loads fabric differently from a torso. Each one maps to a failure we have actually shipped against.

ADD THESE FIELDS FOR A BOTTOM

Weight unit, both ways Wovens are quoted in oz/yd², knits in GSM, and 1 oz/yd² = 33.9 GSM. Write both numbers so nobody converts for you. “Blank” means a 10 oz request comes back as a 10 oz “near enough.”
Spirality/torque max Knit bottoms only. State a maximum percentage and require open-width finishing. Blank means twisted legs are nobody’s fault.
Growth after extension Not stretch recovery. Max residual growth after the fabric is elongated, held, and released. Blank means baggy knees are a surprise.
Crocking, dry, and wet The seat and inner thigh rub against car seats, sofas, and shoes. State minimum grades on dark shades: 4 dry / 3 wet. Blank is the single most common post-delivery complaint on Dark twill.
Fabric width + usable width Long pattern pieces mean leg panels drive marker efficiency, and marker efficiency is a line item in your fabric cost. “Blank” means you pay for the mill’s edge waste.
Relaxation before cutting Stretch and knit fabric must be relaxed and spread before cutting. We hold a minimum of 24 hours. Blank is why “the sample fits, but production runs small.”
Denier and GSM on synthetics Denier is a yarn measure, not a fabric weight. Two 70D fabrics can feel completely different. Give both.
Coating vs. weave State whether the hand comes from the construction or from a PU/acrylic finish that may wear off. Approve a physical swatch either way.
DWR chemistry On any water-repellent bottom: PFAS-free, with a written compliance certificate. See Chapter 4; this is a legal requirement in several US states, not a preference.

Write it as one sentence, then attach the table:

The sentence is for the person reading quickly. The table is for the mill. A woven example:

3/1 cotton twill, 10 oz / 339 GSM ±5%, 100% cotton, enzyme washed, 150 cm usable width, max residual shrinkage 3% L / 3% W after 3 domestic wash cycles, crocking min grade 4 dry / 3 wet, relaxed 24 h before cutting.

Approve the fabric before you approve the garment:

The sequence that prevents most disputes is boring and works:

  1. Fabric submission first. Physical swatches against your spec, in your actual colors, with mill test reports. Sign and date one; the factory keeps a matching one.
  2. Wash test on the approved fabric before cutting bulk shrinkage, spirality, and color. On the fabric that will be cut, not the swatch card.
  3. Fit sample in the approved fabric. A fit sample in substitute fabric tells you almost nothing about how a bottom will hang, because drape and thickness drive the whole silhouette.
  4. Pre-production sample in bulk fabric, bulk trims, and final decoration. The last honest checkpoint.
  5. Inline and final inspection against measurements, with a defined tolerance per point of measure.

On our floor, that runs to 7-10 days per sampling round, matches the live bottoms page, 3-5 days for PP approval, and 8-30 days for bulk after PP sign-off, with a minimum of 50 pieces per style confirm against the MOQ & pricing page]].

CHAPTER 8 IN ONE LINE

Fill the standard spec list, then add the nine fields above: unit conversion, spirality, growth, crocking, usable width, relaxation, denier, coating, and DWR, because those are the ones a bottoms order fails on.

09

The full comparison table:

One screen, every family. Use it to shortlist, then go back to the chapter for the detail.

Fabric Type Typical weight Drape Durability Warmth Relative cost Use it for
French terry Knit 240-380 GSM Soft, fluid Medium Medium Medium Joggers, sweat shorts, sets
Fleece Knit 280-450 GSM Full, voluminous Medium High Medium Sweatpants, winter joggers
Cotton twill Woven 7-12 oz Structured High Low-medium Medium Cargos, chinos, work pants
Duck canvas Woven 8-14 oz Rigid Very high Medium Medium-high (sewing cost) Carpenter and painter pants
Cotton ripstop Woven 5-8 oz Crisp, light High (tear) Low Medium Utility cargos, shorts
Nylon ripstop Woven 20D-210D+ Light, papery High (tear) Low Medium-high Shell and packable bottoms
Nylon taslan Woven 90-140 GSM Crisp, billowing Medium Low Medium-high Parachute pants
Poly taffeta Woven 80-130 GSM Smooth, light Medium Low Low Track and wind pants
Poly-cotton twill Woven 7-11 oz Structured Very high Low-medium Low-medium Workwear-leaning bottoms
Stretch twill Woven 7-10 oz Structured, mobile High Low-medium Medium Slim and tapered pants
10

Five mistakes we see on almost every first-bottoms order:

1. Choosing fabric from a photo:

A photo shows color and a rough sense of volume. It cannot show weight, hand, recovery, or finish.

Two pants that look identical online can be 280 GSM and 400 GSM.

Always work from physical swatches, and keep the ones you reject; the rejects are how you explain what you do want.

2. Copying a top’s fabric onto a bottom:

A 400 GSM fleece that feels perfect as a hoodie can be heavy and hot as a pant because a trouser wraps the whole leg and the fabric sits against more of the body.

Sets often need the same fabric for visual match, but check the pant version on a body before committing to the whole program.

3. Ignoring the waistband and cuff:

Brands specify the body fabric carefully and let the factory choose the rib and the elastic.

Then the waistband rolls, the cuff relaxes, and the pants look cheap.

Specify the rib weight and composition, the elastic width and type, and whether the waistband is a single or double layer.

4. Skipping the wash test:

It costs one garment and two days. It catches shrinkage, spirality, color bleed, print cracking, and elastic recovery all at once.

There is no cheaper quality intervention in the whole process.

5. Approving in the wrong light:

Fabric color approved under warm workshop light will not match what the client sees.

Color approvals should happen under a standard light source, a D65 lightbox, and the light source should be named in the approval record.

Metamerism, where two shades match under one light and diverge under another, is real and expensive.

FROM THE FLOOR

Of the bottom samples that came back for a second round on our floor last season, roughly 60% were fabric or finish issues, not fit. Fit gets all the attention in tech packs. Fabric causes most of the rework.

Questions we get asked

An 80/20 cotton-polyester French terry at 320 GSM, compacted and open-width finished.

Cotton hand, enough polyester to control shrinkage and stop the knee bagging, and a weight that works across seasons on a leg.

Move to a lightly brushed fleece at 380 GSM if you want warmth over versatility.

8-10 oz cotton twill for an everyday relaxed cargo.

Go to 11-12 oz if you want a stiff, wide, structured leg.

Go down to 7 oz only if the fit is slim, and you are adding light elastane twill on a slim fit that wears through at the inner thigh first.

Ripstop if the pants will meet snags: tools, bike chains, gravel, and fence wire.

The reinforcement grid stops a tear from running, so a puncture stays a small hole.

Canvas if the pants will take constant rubbing and you want a structured, standing silhouette. Canvas is heavier, slower to break in, and costs more to sew.

That is spiral residual twist in the knit, releasing in the wash and rotating the seam around the leg.

It is a fabric and finishing issue, not a sewing fault, and it shows on bottoms far more than on tops.

Specify open-width finished fabric and a maximum spirality percentage, and test before you cut bulk.

Light nylon, nylon taslan, or crinkle nylon in roughly the 70-140 GSM range covers most parachute and windbreaker bottoms.

The volume comes from the pattern, not from the fabric weight; a heavier nylon makes the garment stiff rather than fuller.

Note that crinkle is heat-set, so it must never be pressed flat in production.

Not always. Knit bottoms already stretch, and wide or relaxed woven fits usually have enough ease without it.

Add 2-3% elastane when the fit is slim or tapered, when the wearer needs to move, or when you want a cleaner line without adding ease.

When you do add it, specify recovery as well as stretch.

For a set, yes, the same fabric and ideally the same dye lot, or the two pieces will read as mismatched on a rail.

But check the pant version on a body before committing to the program:

A weight that feels right as a hoodie often runs hot and bulky as a pant, because a leg wraps more skin and loads the crotch seam.

Yes, but the pattern usually has to change.

A jogger pattern cut for 320 GSM terry will not hang the same in nylon taslan or 11 oz canvas drape; thickness and seam behavior are all different.

Treat a fabric change as a new fit, not a swap.

From the BOTTOMS manual

This is one chapter of The Complete Bottoms Manufacturing Guides:

These chapters cover taking a Bottoms brand from idea to shipped units, costing, sourcing, tech packs, QC, freight, and launch comparisons. All written from the Sialkot factory floor of Gibben Clothing.

Open The Full Bottoms Guides

On the floor · Sialkot

Written by

Faizan Ahmad

Chief Apparel Technologist & Head of Manufacturing, Gibben Clothing · Sialkot, Pakistan

Faizan leads production at Gibben Clothing, a cut-and-sew streetwear manufacturer in Sialkot, with 8+ years turning raw yarn into retail-ready hoodies, tees, bottoms, jackets, tracksuits, and headwear. He doesn’t just write about clothing; he works the floor, so every guide here is grounded in real fabric behavior, QC standards, and production data from live runs.