A brand sends us a reference pant. It is a vintage pair of sweatpants, washed a hundred times, perfect.

The tech pack says “heavyweight fleece.” That is the whole fabric spec.

We can sample from that. But we are guessing. “Heavyweight” to one mill means 340 gsm.

To another, it means 480 gsm. Those two pants are not variations of each other. They are different products, at different prices, for different seasons.

This guide answers one question: what is the best GSM for joggers and sweatpants for your product?

If you are still choosing between fleece, terry, twill, and nylon, start with our bottoms fabric guide and come back.

If you already know you are making a jogger, sweatpants, or sweat shorts, this is where you pick the number.

Bottoms deserve their own weight guide for one reason: a pant is not a top with legs.

Weight behaves differently once the garment has to bend at the knee, stretch across the seat, stack on a sneaker, and carry its own hem.

Every rule you learned for spec’ing hoodies needs an adjustment before it applies here.

1. What GSM means for joggers and sweatpants:

The correct mental model first. Most weight mistakes on bottoms come from carrying a hoodie instinct onto a pant.

GSM is grams per square meter: the mass of one square meter of fabric.

It is a weight, not a thickness, and not a quality score.

Fabric, construction, yarn, and finish all change how a given number feels in the hand. We cover all of that, plus the oz/yd² conversion (1 oz ≈ 33.9 gsm), in our complete GSM guide.

This chapter is only about what changes when that number is wrapped around a leg.

Four reasons the same GSM behaves differently on a pant:

  1. It bends constantly. A hoodie hangs off the shoulders and is mostly unloaded. A pant flexes at the knee with every step and far more when the wearer sits. Stiffness that reads as “substantial” on a torso reads as “restrictive” at the knee within minutes.
  2. It is loaded in tension. Sitting stretches the seat across the widest, most curved part of the body. That is where thin fabric goes transparent and where heavy fabric pulls the rise down.
  3. It is a tube. Seam allowances stack inside a narrow leg, and several seams converge at the crotch. Weight you never notice at a hoodie shoulder becomes a hard ridge you feel when you sit.
  4. It carries its own hem. A pant leg either stacks on the shoe or hangs clean. Both behaviors depend on weight, and neither exists on top.

The practical upshot: pick the bottom’s weight for the leg, not for the outfit.

A pant that matches the hoodie on a rail but fights the wearer by lunchtime is the wrong pant.

Reading the weight of a reference pant:

Most briefs start with a pant the founder already loves. Before you write a number, find out what that pant actually weighs. Two ways:

  • Cut a disc from a hidden self-fabric area. A pocket bag in self-fabric, or the inside of a deep hem turn-up, usually gives room for a 100 cm² disc without visible damage. Weigh it, multiply by 100, and done.
  • Estimate from the whole garment when the reference is too precious to cut. Weigh the pant, subtract trims, and divide by the total fabric area from a similar pattern. It is close enough to choose a band on the ladder below not close enough to write into a tech pack.

Either way, you now brief with a number instead of an adjective. That alone removes a sampling round.

From our floor

Every incoming knit roll for a bottoms order is conditioned in the QC room first, because damp cotton weighs heavily.

Then it is cut at the head, middle, and tail of the roll with a 100 cm² GSM cutter and weighed on a precision scale.

A roll outside the agreed ±5% is flagged before it reaches the cutting table.

A 20 gsm drift across a production run is the difference between the pant a buyer approved and the ones they reject.

2. The jogger GSM ladder, 240-500 gsm:

This is the spec menu. Find the row that matches the product you are describing, then take the number to your factory.

French terry and brushed fleece cover the overwhelming majority of streetwear bottoms.

Here is the whole jogger fabric weight ladder, band by band, with what each one actually produces on a leg.

GSM Band Best for Watch out for
220-260 Ultralight terry Travel pants, resort lounge, very hot markets Opacity in anything but dark colors; clings and shows every contour
260-300 Light terry Sweat shorts, summer joggers, layering pants Little structure; a taper will not hold without a firm rib cuff
300-340 Midweight terry The year-round jogger. Our default recommendation for a first style Reads generic if the fit is generic; yarn and finish carry the quality
340-400 Standard sweatpants Light-brushed fleece sweatpants, autumn/winter core Often marketed as “heavyweight,” buyers who own real 450s disagree
400-450 Heavyweight Premium sweatpants, matched heavyweight sets, garment-dyed programs Bulk at the crotch and cuff; shrinkage must be controlled before cutting
450-500 Luxury Flagship pieces, loopwheel-style capsules, $120+ retail Slower sewing, long dry time, stiff knee until broken in
500+ Not recommended Rarely right for a pant Needle breaks, hard seam junctions, high reject rate, restrictive wear

220-300 GSM: the summer band

This is a genuinely different product, not a cheap version of a sweatpant.

A 270 gsm French terry short or jogger is a warm-weather garment.

It breathes, dries fast, packs flat, and sells in markets where a 400 gsm pant is unwearable eight months of the year.

The mistake brands make is pricing it as a light version of their winter pants.

Merchandise it as its own thing: shorter lengths, a lighter color palette, and often an open or rolled hem on shorts.

The hard constraint here is opacity. Anything under 280 gsm in white, cream, grey marl, or pastel needs a seat check before approval. Chapter 6 covers the test.

What to pair it with:

  • A firm rib cuff or elastic hem on joggers. Light fabric has no weight to hang an open hem straight.
  • Narrow to regular taper. A wide leg at 260 gsm collapses instead of flowing.
  • Ring-spun or compact yarn. Open-end yarn at this weight looks thin and tired after five washes.

300-400 GSM: the workhorse band

If you are launching a first jogger with no strong opinion yet, start here.

Specifically, start at 320 gsm 80/20 French terry, compacted and open-width finished.

It works in three seasons; it is a stock weight at most mills, it is opaque in every color except white, and it holds both a taper and a relaxed leg.

Move to light-brushed fleece in the 340-400 range when warmth matters more than versatility.

That is the classic sweatpants, and it is where most mid-market autumn/winter programs sit.

The risk in this band is being invisible. A 340gsm jogger with a standard fit is the most common garment in the category.

The way out is not more weight. It is yarn, finish, and fit: compact-spun yarn, a garment dye or enzyme wash, and a deliberate rise and taper.

A well-made 320 beats a badly made 450 every time.

400-500 gsm: the premium band

This is where the pant starts to feel like an object. The leg falls in a column instead of following the thigh.

The waistband tells a customer, in about two seconds of touching it, that they are holding something expensive.

It is also where most of the defects in incoming samples come from. Three things change:

  • Shrinkage costs more length. Heavier cotton knits hold more water and move more in absolute terms. On a full-length pant, a few percent of the length’s shrinkage is the difference between stacking on the shoe and grazing the ankle. Compacted, pre-shrunk fabric is not optional here.
  • The crotch junction hardens. At 450 gsm, the point where the seams converge becomes a solid knot of cotton under the needle. Construction has to change to keep it flat.
  • Sewing slows down. Operators take longer per piece, needle breakage rises, and thread tension needs resetting for the heavier plies. Chapter 7 puts that into the cost sheet.

Above 500 gsm, those problems stop being manageable on a pant.

If maximum weight is the goal, 460-500 gsm with excellent finishing beats 550 gsm with compromises.

From our floor

On fleece above 400gsm, treat the crotch junction as its own operation, not just the end of the inseam.

Trim and stagger the seam allowances so they don’t all land on one point, step up the needle size for the heavier plies, and check the junction lies flat by hand before the waistband goes on.

The test any buyer can run on a heavyweight sample: turn it inside out and pinch the crotch point between finger and thumb.

If it feels like a knot in your hand, the wearer will feel it every time they sit.

Season, mapped to the ladder:

Season/market Knit GSM Note
Summer, hot climates (Gulf, South Asia, SE Asia) 240-300 Terry, cotton-rich, light colors need an opacity check
Year-round, temperate 300-340 The safest single weight for a core jogger
Autumn/winter, temperate 340-420 Light-brushed fleece; pairs with a 380-450 gsm hoodie
Deep winter (Northern Europe, Canada) 400-480 Consider a brushed or double-faced construction before adding raw weight

Weight across one range:

Don’t run one weight across every bottom in a collection. A sweat short, a year-round jogger, and a winter sweatpant want three different rungs.

A three-piece knit bottoms range that works:

A 280 gsm terry short, a 320 gsm terry jogger, and a 400 gsm brushed fleece sweatpant, all in the same yarn and finish so the family still reads as one brand.

3. Heavyweight GSM sweatpants and the 40-gram drop:

The heavyweight hoodie pulled the bottoms up with it. Here is what the trend actually asks for, and the one place where copying the hoodie spec backfires.

For roughly the last five years, the center of gravity in streetwear fleece has moved up. The 280 gsm hoodie became a 350, and the 350 became a 450.

Weight became a stated selling point, printed on product pages next to the fit.

Bottoms followed, because matched sets sell. A customer who buys a heavyweight hoodie wants the pant that goes with it.

The top-side numbers are in our hoodie GSM comparison, and the washes that usually come with this look are in our garment wash and dye guide.

Why is the trend real, not just marketing?

  • Weight is the one quality signal a customer can judge through a screen. They cannot feel your stitch density. They can read a GSM figure and compare it to a competitor’s.
  • Heavier pants survive washing better. Dense fabric holds its shape and resists pilling. The pant still looks right at wash twenty, which is when repeat purchases get decided.
  • It justifies price. More fabric per unit is a reason to charge more that customers accept without feeling sold to.

The mistake: copying the hoodie weight onto the pants

Here is where we push back on most matched-set tech packs.

A hoodie and a pair of pants with identical GSM do not feel identical on the body. The hoodie hangs.

The pant bends, sits, and stretches. A leg also wraps more skin than a torso, so the same fabric runs hotter.

Fabric that reads “substantial” on a hoodie reads “stiff and warm” on a pant after a few hours at a desk.

The 40-gram drop:

Keep the set in the same fabric quality, same construction, same yarn, and same finish, but knit the pant one step lighter: 30-50 gsm under the hoodie.

A 450 gsm hoodie pairs with a 400-420 gsm pant. The set still reads as one product, the hand still says premium, and the pants stay comfortable all day.

For a 400 gsm hoodie, that means a pant around 350-370 gsm. For a 350 gsm hoodie, around 320 gsm, which lands neatly on the year-round jogger weight.

The trade-off: comfort vs. a perfect shade match

Be clear about what the drop costs you. Two weights mean two fabrics, and two fabrics can’t come off the same roll.

  • Want a guaranteed shade match from one roll? Cut both pieces from the same fabric. That is how our matched tracksuit sets are built: one dye lot, same roll where possible, inspected as a pair. The pant will be as heavy as the hoodie, so choose a weight that works on the leg: 400 gsm rather than 480.
  • Want the 40-gram drop? Approve the lab dip against both fabrics together, or garment-dye the set as a pair so the shade is identical by definition. Garment dye is the most reliable way to get a true tonal match across a hoodie and sweatpants.

If you publish GSM on the product page, publish both numbers: “450 GSM hoodie, 410 GSM pants.”

Customers who compare specs will notice anyway. Framed as a deliberate comfort choice, the difference becomes proof that you know what you’re doing.

What “premium heavyweight” needs beyond the number?

Brands that buy heavy fabric and skip everything else end up with a thick pant that still looks cheap. The rest of the package:

  1. Compact or ring-spun yarn. Heavy open-end fleece is thick and rough. The weight is there; the quality is not.
  2. Controlled shrinkage. Compacted and pre-shrunk, with residual shrinkage of 3% or less in both directions after three home washes.
  3. Trims at the same weight. A 450 gsm pant with a thin drawcord and a flimsy tip undoes the impression at the first touch.
  4. Rib that can hold the leg. A light rib on a heavy body stretches out within a month. Match rib weight to body weight (chapter 8).
  5. A finish that breaks the stiffness. Garment dye, enzyme wash, or pigment overdye gives new heavy fabric the lived-in hand people associate with the price.

4. Twill, ripstop, and nylon: the weight rules that change:

Woven bottoms get their full treatment in the bottoms fabric guide. This chapter covers only how weight thinking changes once you leave knits.

Cargos, work pants, chinos, and technical shells are covered in fabric by fabric in the twill, ripstop, and nylon chapters of our bottoms fabric guide.

Three weight rules carry over from them, and they belong on the same page as the knit ladder:

Rule 1: on wovens, weight sets the silhouette, not the warmth

On a knit jogger, going heavier mostly adds warmth and structure. On twill and canvas, going heavier changes the shape.

A light twill collapses around the leg. A heavy twill stands away from it. So choose woven weight from the silhouette you want, not from the season.

Rule 2: the unit changes

Fabric Quoted in Working range for bottoms
Cotton twill oz/yd² 8-10 oz relaxed cargo; 10-12 oz wide, structured leg; 7-8 oz chino
Duck canvas oz/yd² 10-12 oz for wearable workwear
Cotton ripstop oz/yd² 6-8 oz for utility cargos
Nylon / technical Denier and GSM 20-70D shell and parachute; 70-150D track and wind pants; 210D+ hard-wearing cargo shells

For synthetics, always give denier and fabric GSM together.

Denier describes the yarn; GSM describes the finished cloth, including any coating.

Either one alone leaves room for a very different fabric to arrive.

Rule 3: in mixed-fabric bottoms, every panel needs its own weight

This is the one that catches brands building hybrid pants: a fleece jogger with nylon knee panels, a twill cargo with rib cuffs, and a terry short with a woven waistband.

  • Heavy panel next to light panel: the seam pulls toward the heavy side. A 70D nylon overlay on 420 gsm fleece puckers along the join unless the nylon is backed or the fleece is lighter at that panel.
  • Rib cuffs on a woven leg need more weight than on a knit leg. Twill gives the cuff nothing to stretch with, so a light rib flares within weeks.
  • Pocket bags shouldn’t match a heavy body. A 420gsm self-fabric pocket bag adds bulk at the hip for no benefit. A lighter self-color jersey keeps the line clean.

Write a weight for every fabric in the bill of materials, not just the main body. Unspecified panels get filled with whatever the mill has on the shelf.

5. How sweatpants fabric weight changes drape, stacking, and fit

The design consequence. This is why the same pattern, cut in two weights, produces two different-looking pants.

Take one pattern. Cut it in 280gsm terry and again in 450gsm fleece.

Put both on the same fit model. They will not look like the same garment.

Stiffness rises much faster than weight:

Bending stiffness in a fabric rises roughly with the cube of its thickness.

In plain terms, a modest increase in weight produces a big increase in how strongly the fabric resists bending.

That is why the step from 380 to 450 gsm feels far bigger than the 18% on paper.

It is also why 240 to 300 gsm turns a clingy pant into one that holds its own shape, for only 60 grams.

What each band does to the silhouette?

 
Weight Silhouette behavior Design implication
Light
240-300		 Follows the body. Falls into the space behind the knee and along the thigh The fit does the work. A slim cut reads intentional; a wide cut reads shapeless
Mid
300-400		 Neutral. Hangs mostly straight, with some body-following at the thigh Most forgiving. Almost any leg shape works
Heavy
400-500		 Holds its own column. The leg keeps its shape regardless of the body inside The pattern is the silhouette. Wide legs actually stay wide

Stacking:

Stacking the folds that gather on the shoe is a deliberate streetwear effect, and it depends on weight. Three things produce a good stack:

  1. Length. Extra inseam beyond the ankle, usually 3-6 cm over standard.
  2. Leg opening. Wide enough for the fabric to fold rather than compress. Under roughly 36 cm at the hem, it bunches instead of stacking.
  3. Weight. Enough mass to fold into clean horizontal breaks rather than soft crumples.

Below about 300 gsm, you get crumple, not stack. Between 320 and 420 gsm, you get the clean, defined breaks people are after.

Above 450 gsm, the folds get heavy enough to push the leg outwards and sit oddly on a narrow shoe.

Hem finish by weight:

  • Rib cuff. Works at any weight, provided the rib is weight-matched to the body.
  • Elastic hem. Best on light-to-mid terry. On heavy fleece, the elastic fights the fabric and the hem flares.
  • Open hem. Needs weight. At 260 gsm it flaps and curls. At 400 gsm it falls straight and looks expensive.

Fit and sizing by weight:

Heavier fabric gives less. A 450 gsm pant cut to the same measurements as a 320 gsm pant feels tighter at the seat, thigh, and knee because the fabric won’t stretch to make room.

It is the same effect we see on heavyweight hoodies, where we advise customers to size up at 450 gsm and stay true to size at 350.

  • Add ease when you go heavy. Grade the extra room through the seat and thigh on the heavyweight block, and confirm it on a fit sample in the real fabric drape, and it can’t be judged from a swatch.
  • Check the rise seated. Heavy fabric pulls the back down when the wearer sits. Add back rise before you think about dropping weight.
  • Tell customers. If your heavyweight pants fit differently from your midweight, say so on the size guide. It is cheaper than the returns.

Weight and decoration on a leg:

Leg decoration sits on a curved, moving surface, which makes weight matter more than it does on a hoodie chest:

  • Large thigh prints on light terry (under ~300 gsm) stiffen the panel and crack along the knee crease. Go heavier, or use a softer ink system.
  • Embroidery on a leg puckers on light fabric because the panel flexes. A backing helps; 340 gsm and up helps more.
  • Polyester-rich heavy fleece can release dye into a light print under cure heat. Ask for a dye-blocking underbase on dark poly fleece.

The seat and knee test:

Fit sessions on bottoms should always include sitting, squatting, and a full stride. Standing fits hide every weight problem:

  • Does the knee bag out after being held bent for two minutes? The fabric is too light or lacks recovery.
  • Does the knee resist bending or crease sharply? The fabric is too heavy for the pattern.
  • Does the rise pull down when seated? Heavy fabric plus too little rise.

Floor note: fit bottoms in five positions

Fit every size in five positions: stand, sit at 90°, deep squat, stride, stairs, and photograph each one on the same model for every sample round.

It costs a few extra minutes per fitting, and it catches rise and knee problems at the first sample instead of at production, where they cost a full re-cut.

6. The GSM that stops sweatpants from being see-through

The highest-cost mistake in this guide. Thin bottoms generate returns, bad reviews, and a reputation you can’t fix with a restock.

Nobody returns a hoodie because it is see-through. People return bottoms for that reason, and they say so in reviews.

The mechanism is simple. Sitting stretches the seat panel across the widest and most curved part of the body. Stretch thins the fabric locally.

Light passes through. What was opaque on a hanger is not opaque on a chair.

The opacity floors we work to:

Color Minimum knit GSM Note
Black, navy, charcoal, dark olive 240 Dark dyes block light well. Weight is a comfort choice here, not a safety one
Mid-tones: heather, sage, rust, brown 280 Check the seat under stretch before approving
Light cream, sand, pale blue, pink 300 Brushing helps a lot. Test every color, not just one
White and grey marl 320 The two worst offenders. Grey marl shows most because of its yarn mix

The 60-second seat test:

  1. Put the sample on a fit model in your best-selling size.
  2. Have them sit on a hard chair under strong overhead light, then squat.
  3. Photograph the seat from behind in both positions, from about two meters away.
  4. Stretch a flat section of seat fabric over your open hand and hold it to a window. If you can clearly see your fingers, they are too thin.
  5. Repeat for every colorway. One approval does not cover the range.

Four ways to fix opacity without adding weight:

  • Brush the back. A raised nap scatters light and adds real opacity at the same GSM.
  • Ask for density, not mass. A tighter knit at the same weight is more opaque than a loose one.
  • Move to a textured yarn but not grey marl. A slub or two-tone yarn breaks up light visually.
  • Line the seat. A partial lining from waistband to mid-thigh solves it completely on light summer styles for very little cost.

How customers judge weight before they look?

Customers assess a pant in a predictable order. They pick it up (mass). They touch the waistband (density and rib).

They rub the fabric between the finger and thumb (surface). Then they look at the stitching.

That is three physical judgments before anyone reads your label, and all three are about weight.

It is why a well-specified 340 gsm pant with a heavy rib and good trims can out-perform a 420 gsm pant with a thin rib and a cheap drawcord.

7. What weight does it add to your cost sheet:

Heavier fabric costs more in four places, not one. Budget for all four before you fall for a 480 gsm sample.

Fabric is the largest single line on a fleece garment, typically 40–55% of the total unit cost on our hoodie costings, and a pant in the same fleece behaves the same way.

So a weight decision is a pricing decision.

The four cost effects:

  1. Fabric mass, directly. Knit fabric is bought by weight. Every gram on the spec is a gram you pay for on every pant.
  2. Sewing time. Heavy plies are slower to handle, and needle breaks and tension resets add up. On our floor, heavy canvas bottoms run 15-20% more SAM (standard allowed minutes) than the same pattern in mid-weight twill; heavy fleece pushes the line in the same direction.
  3. Finishing. Wet processing is priced by weight. A garment dye or enzyme wash on a heavier pant costs more per piece and takes longer to dry.
  4. Freight. Air freight is priced by weight outright, and heavy fleece is bulky by sea too. The same order ships more meaningfully dearer at 450 gsm than at 340 gsm.

How much more fabric each step buys?

Taking a 320 gsm jogger as the baseline, here is how much more fabric mass you are buying per pant as you move up the ladder before sewing, finishing, or freight are added on top.

Body GSM Fabric mass vs. 320 gsm What else moves?
280 −12.5% Cheapest, but opacity limits the color range
320 baseline Stock weight at most mills; no special knit run
360 +12.5% Small step; usually still a stock weight
400 +25% Shrinkage control and heavier ribs become mandatory
450 +41% Slower sewing, longer drying, heavier freight
500 +56% All of the above, plus a higher reject rate at the crotch junction

For a real-world reference point from the top side of the set, our hoodie quotes for one client moved from $30 to $40 to $50 per unit across 280, 350, and 450 gsm, at a 50-unit MOQ with chest embroidery and a back print.

Bottoms follow the same shape. The heavier pant costs more than the weight difference alone suggests, because sewing, finishing, and freight all move with it.

Where is the weight of money best spent?

If your fabric budget is fixed, spend it in this order:

  1. Yarn first. Ring-spun at 340 gsm beats open-end at 420 gsm on every quality cue except raw mass.
  2. Trims second. Heavy ribs and a proper drawcord with metal tips are cheap per unit and touch the customer directly.
  3. Finish third. A garment dye or enzyme wash transforms mid-weight fabric.
  4. Raw GSM last. Add weight once the first three are handled.

Stock weights vs. custom weights:

Your real minimum on a jogger is two floors. The garment floor is set by the sewing line, typically 50-200 pieces per style for joggers and sweatpants.

The fabric floor is set at the mill: a custom knit or custom dye lot commonly needs around 300 kg of fabric per color. Our MOQ guide walks through both.

That is why weight choice and minimums are linked. Ask two questions early:

  • What is the mill’s stock weight nearest my target, and what would I lose by using it?
  • If I need a custom weight, what is the fabric floor per color, and how many weeks does it add?

Very often, a stock 400 gsm already on the shelf serves the product better than a custom 420 gsm that triggers its own dye lot.

And if the hoodie and joggers share one fleece in one color, they share one fabric floor instead of two.

Floor note: fit bottoms in five positions

Fit every size in five positions: stand, sit at 90°, deep squat, stride, stairs, and photograph each one on the same model for every sample round.

It costs a few extra minutes per fitting, and it catches rise and knee problems at the first sample instead of at production, where they cost a full re-cut.

8. How to specify the jogger GSM in your tech pack?

The action step. Everything above only counts if the number survives the trip to the cutting table.

The core weight spec target is GSM with a ±5% tolerance; finished, not greige, construction, yarn, and the measurement method are the same for every garment, and it is set out in the tech pack chapter of our GSM guide. Write that first.

Then add the weight fields that only matter on bottoms:

  1. Post-dye GSM for garment-dyed pants. Garment-dyed pants shrink in the bath and finish heavier per square meter than the fabric they were cut from. State the weight you want after dyeing, or the pants arrive heavier and shorter than you planned.
  2. A length-shrinkage limit on the inseam, measured on the finished garment, not just the fabric. Length is the one measurement customers notice on a pair of pants.
  3. Rib weight matched to body weight. As a working rule: body under 340 gsm, rib around 320 gsm; body 340-420 gsm, rib 340-380 gsm; body above 420 gsm, rib at the heavy end with 3-5% elastane. Write the rib weight explicitly.
  4. A seat opacity clause: passes the seated stretch test in the lightest colorway.
  5. A weight for every panel in mixed-fabric styles: overlays, pocket bags, waistband facings.
  6. Matched-set weights are stated together, so the hoodie and pants are spec’d as one decision: “hoodie 450 gsm/pants 410 gsm, same fabric quality, garment-dyed as a pair.”

For the remaining bottoms-only fields, spirality, growth after extension, crocking, and relaxation before cutting, see the bottoms spec fields chapter of the fabric guide.

A weight block you can copy:

Field Example value
Body fabric Light-brushed fleece, 80% combed cotton / 20% polyester, ring-spun
Body weight 410 gsm ±5%, finished, measured after garment dye
Matched top Hoodie 450 gsm, same fabric quality, garment-dyed as a pair
Rib (cuff + waistband) 2×2 rib, 360 gsm, 5% elastane
Pocket bag Self-colored jersey, 180 gsm
Inseam shrinkage ≤3% after 3 × 40°C wash + tumble, measured on garment
Opacity Passes seated stretch test in the lightest colorway
Reference Approved swatch (e.g., BTM-FL-410-01), signed and dated, one copy held by each side

Pre-production weight checklist:

  • Body weight stated with a tolerance and a measurement point (finished, post-dye if garment-dyed).
  • Weight chosen from the ladder for the season, not copied from the hoodie.
  • Matched sets: decided between one shared fabric or a 30-50 gsm lighter pant, with the shade-match method written down.
  • Rib weight written explicitly and matched to the body.
  • Every secondary panel and pocket bag has its own weight.
  • Opacity checked on the seat under stretch in every colorway.
  • Fit approved sitting and squatting, with ease adjusted for heavy weights.
  • Inseam shrinkage tested on the finished garment.
  • Incoming roll weight check agreed in writing (head, middle, and tail).

Decide the number before you sample:

Almost every weight problem we see on bottoms traces back to a number that was never decided.

It was inherited from a reference pant, left to the factory, or copied from the hoodie in the same set.

Pick your season. Pick your silhouette. Find the rung on the ladder.

Write the number down with a tolerance, a measurement point, and a signed swatch behind it. Then sample.

Do that, and the pant that arrives in your warehouse is the pant you designed.

Questions we get asked every week

320 gsm 80/20 cotton-polyester French terry, compacted and open-width finished. It works across three seasons; it is a stock weight at most mills; it is opaque in everything except white; and it holds both a taper and a relaxed leg. Move to a light-brushed fleece at 340-400 gsm if warmth matters more than versatility.

400-450 gsm is heavyweight for a pant. 450-500 gsm is luxury territory, worth it only with excellent yarn and finishing.

Above 500 gsm, we don’t recommend it on bottoms: the crotch junction hardens, sewing slows, and the knee stays stiff.

Usually not. Keep the same fabric quality, but knit the pant 30-50 gsm lighter: A 450 gsm hoodie pairs with a 400-420 gsm pant, and the pant stays comfortable through a day of sitting.

Two weights can’t come off one roll, so match the shade with a lab dip approved on both fabrics or by garment-dyeing the set together.

If an exact same-roll match matters more than comfort, cut both from one fabric at a weight that works on the leg, around 400 gsm.

260-300 gsm French terry. Shorts are a warm-weather product, so breathability matters more than heft.

Check opacity on light colors: under 280 gsm, cream and grey marl can show through at the seat.

240 gsm for black and dark colors, 280 for mid tones, 300 for light colors, and 320 for white and grey marble.

Test every colorway with the fabric stretched over the seat under strong light, not on a hanger. Brushing the back adds opacity without adding weight.

Yes. Heavier fabric stretches less, so a 450 gsm pant feels tighter through the seat, thigh, and knee than a 320 gsm pant cut to the same measurements.

Add ease to the pattern when you go heavy, check the back rise seated, and note the difference on your size guide.

Usually one of three things. The sample was cut from a different lot or finish.

The tech pack gave a weight with no tolerance, so the mill delivered at the low end.

Or the weight was agreed on for the grey fabric, and the production lot finished differently.

A tolerance, a finished-weight measurement point, and signed swatches prevent all three.

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.