Turn over almost any pair of leggings or any sports bra and you'll find some version of the same label: nylon and spandex, or polyamide and elastane. Different names, same two fibres doing the same two jobs.
Understanding what each one contributes makes composition labels genuinely useful when you're deciding what to buy.
The naming confusion, cleared up
Manufacturers use different regional terms for identical fibres:
- Nylon = polyamide. Same fibre. "Polyamide" is the European convention.
- Spandex = elastane = Lycra. Same fibre. Lycra is a brand name.
So a label reading 80% polyamide / 20% elastane and one reading 80% nylon / 20% spandex describe exactly the same fabric.
What nylon does
Nylon is the structural fibre. It provides:
- Strength. Nylon has excellent abrasion resistance, which is why it survives repeated stretching and gym equipment.
- Smoothness. It has a soft, slightly slippery hand feel that sits comfortably against skin.
- Moisture movement. Nylon doesn't absorb much water. Sweat moves along the fibre to the surface and evaporates rather than soaking in.
- Colour retention. It takes dye well and holds it.
What nylon doesn't do is stretch meaningfully on its own. That's the other fibre's job.
What spandex does
Spandex can stretch to several times its length and return to shape. It's what makes a legging a legging rather than a stiff tube.
Two properties matter:
Stretch — how far it goes. This is what lets you squat and lunge.
Recovery — how well it returns. This is the more important one, and the one that fails first. Fabric with poor recovery bags out at the knees and seat after an hour of wear.
How to read the percentages
The spandex percentage is the number worth checking.
| Spandex content | What it means |
|---|---|
| 5% or less | Minimal stretch. Fine for joggers and relaxed pants, not for fitted leggings. |
| 8–12% | Moderate stretch. Suitable for shorts and looser training pieces. |
| 15–20% | The sweet spot for leggings and sports bras. Real compression and reliable recovery. |
| 25%+ | Very high compression. Common in bike shorts and high-support bras. |
Across our range: the high-waisted yoga leggings are 80/20, the biker shorts are 75/25, and the men's joggers are 95/5 polyester-spandex — deliberately less stretch, because a jogger shouldn't compress.
Why not polyester?
Polyester is the other common activewear fibre, and it's not worse — it's different.
Polyester is cheaper, dries faster and resists creasing better. Nylon is softer, stronger and more comfortable against skin.
As a rough guide, polyester tends to appear in tees, shorts and outer layers, while nylon dominates in leggings and bras where next-to-skin feel matters most.
The one weakness
Synthetics hold odour more than natural fibres do, because bacteria feed on the oils that sit on the fibre surface rather than being absorbed into it.
This is manageable — wash cold, skip fabric softener, and don't leave kit in your bag. We covered the full method in the activewear care guide.
What to take from this
When you're comparing two similar products, the composition label tells you more than the description does. Look for 15% or more spandex in anything fitted, and treat a very low spandex figure in a legging as a warning sign.
Shop the full range at WTD.