Activewear Fabric Guide
Fabric decides how a garment feels, how it survives washing, and how much it costs. It is also the specification buyers get wrong most often — usually by choosing a GSM that does not match the product.
Nylon-spandex versus polyester-spandex
Nylon-spandex is the standard for leggings and sports bras that need a soft hand, good recovery and a matte surface. It takes dye deeply, holds colour well, and feels cooler against skin. It costs more per kilogram and is the reason a good legging costs more than a good top.
Polyester-spandex is cheaper, dries faster, and holds up well in high-abrasion training wear. Its hand is drier and less buttery, and cheaper versions can feel slick. For gym and training tops, shorts and outer layers it is a sensible choice; for a premium legging it is not.
A practical split: nylon-spandex for the pieces that touch skin and define the brand (leggings, bras), polyester-spandex for the pieces that take abuse (training tees, shorts, jackets).
GSM by product type
GSM is grams per square metre and it is the fastest proxy for how substantial a fabric feels. A 190–200 GSM knit reads as light and is right for tops and summer shorts. 220–240 GSM is the leggings range — opaque, supportive, and heavy enough not to show through in a squat. 250–280 GSM is compression and outerwear territory, and beyond that you are into a fabric that fights the wearer unless the pattern is built for it.
The most common failure is a brand choosing 190 GSM for leggings to hit a price, then discovering the product is see-through under stretch. Squat-proof is a function of GSM, knit density and colour — black hides more than a pale pink at the same weight.
Lighter colours need more weight to be opaque. If your range is built on pastels, budget for a higher GSM than your black styles.
Knit structure and what it does
Single jersey is the baseline — light, stretchy, cheap, and prone to showing through. Interlock is denser and more stable with the same face on both sides, which is why it is common in leggings. Rib knit gives mechanical stretch and a textured surface, popular for waistbands and seamless-look bodies.
Seamless construction uses a circular machine to knit the garment in one piece, removing side seams. It gives a smooth silhouette and reduces sewing labour, but the machine dictates the size range and the design freedom — you cannot add a pocket or an arbitrary seam line without a machine reconfiguration.
Stretch, recovery and the number buyers forget
Spandex content is usually quoted as a percentage, but the behaviour that matters is recovery — how far the fabric returns after stretch. A 20% spandex knit that recovers well outperforms a 25% knit that does not. Ask for recovery data, not just the percentage.
Two-way stretch is enough for most tops and shorts. Leggings and bras generally want four-way stretch so the garment moves with the body in both directions without pulling at the seam.
Recycled and sustainable options
Recycled nylon and recycled polyester are both available and both carry a cost premium over virgin. Certification matters more than the claim — without a transaction certificate the recycled content cannot be substantiated to a retailer or a marketplace.
Be specific with us about which certification your market requires before we source, because the certified supply is narrower than the general supply and lead times differ.
How to specify fabric without a textile background
Give us the product, the target retail price, the market, and one reference garment you like the hand of. From that we will propose two or three fabric options with composition, GSM and a note on what each one trades off. That is faster and more reliable than starting from a composition you found online.
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Send the product type, the destination market and your target price. You get a straight answer on what is workable and what is not, before you pay for anything.
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