Spandex is a synthetic fibre made mostly from segmented polyurethane that can stretch to several times its length and spring back. Elastane is the same fibre under the name used in Europe and the UK, and Lycra is a brand name for it. It’s never the whole fabric: a small percentage is blended with cotton, nylon or polyester to give stretch and recovery.
So, what is spandex in practice, and how much do you need? Below: spandex vs elastane vs Lycra, how it’s made, typical percentages by garment, 2-way vs 4-way stretch, care, sustainability and what to put in your tech pack.
What is spandex? Spandex vs elastane vs Lycra
All three words describe the same type of fibre. The difference is who’s talking:
- Spandex is the generic name used in the US and Canada. It’s an anagram of “expands”.
- Elastane is the generic name used in the UK, the EU and most of the rest of the world. It’s the term you’ll see on EU care labels and on most fabric spec sheets from Asian mills.
- Lycra is a trademark. The fibre was developed at DuPont in the late 1950s and the brand is now owned by The LYCRA Company. Lycra is elastane, but not all elastane is Lycra.
So the spandex vs elastane question has a simple answer: there’s no difference in the fibre, only in the name. Spandex vs Lycra is a generic name against a brand. Your factory may offer branded or unbranded elastane; using the Lycra name on your hangtags is normally tied to the fabric being made with the genuine fibre.
On a fibre content label, use the generic name. In the US, “spandex” is standard and “elastane” is also accepted; in the EU, “elastane” is the required term.
How spandex is made
Elastane is a long-chain polymer with alternating soft and hard segments. The soft segments coil up and let the fibre stretch; the hard segments hold the chains together so it snaps back when you let go. By definition, at least 85% of the fibre is segmented polyurethane.
Most elastane is made by dissolving the polymer and dry-spinning it into fine filaments. Those filaments then go into fabric in one of three ways:
- Bare elastane knitted alongside the main yarn, common in leggings, swimwear and lingerie fabrics.
- Covered yarn, where nylon or polyester is wrapped around an elastane core.
- Core-spun yarn, where cotton fibres are spun around elastane, as in most stretch denim.
Spandex percentage by garment
A little elastane goes a long way. The right amount depends on how close the fit is and how much movement the garment has to handle. These ranges are typical, not rules; fabric weight and knit structure matter just as much.
| Garment | Typical elastane content | Usual base fibre | What it does |
|---|---|---|---|
| Stretch jeans | 1–3% | Cotton | Comfort and shape retention; more than 2% feels noticeably stretchy |
| Chinos and woven trousers | 2–3% | Cotton or polyester | Ease of movement in a woven |
| Fitted t-shirts and tanks | 3–5% | Cotton or modal jersey | Better recovery at the neck and body |
| Rib tops and bodysuits | 5–10% | Cotton or modal rib | Close fit that holds its shape |
| Leggings and cycling shorts | 15–25% | Nylon or polyester | Compression, support and opacity when stretched |
| Sports bras | 15–25% | Nylon or polyester | Support and recovery over repeated wear |
| Swimwear | 15–25% | Nylon or polyester | Fit when wet and close to the body |
What spandex percentage is best for leggings?
For gym and yoga leggings, around 20% elastane with nylon is the familiar “second skin” feel, and many brands land between 15% and 25%. Higher elastane gives more compression; nylon-based fabrics feel softer and smoother, while polyester-based ones tend to cost less and handle moisture well.
Percentage alone won’t tell you whether leggings are squat-proof. Fabric weight, knit density and the colour of the elastane all affect opacity, so always test a sample on the body.
2-way vs 4-way stretch
Elastane content is only half the story. The other half is the direction the fabric stretches.
- 2-way stretch usually means the fabric stretches in one direction, normally across the width. Stretch denim, chinos and many cotton-elastane jersey fabrics work like this.
- 4-way stretch stretches across the width and along the length. It’s what you want in leggings, sports bras, swimwear and anything that moves with the body.
The terms aren’t used consistently: some suppliers call one-direction stretch “2-way”, others call it “mechanical” or “1-way”. Don’t rely on the label. Ask for the stretch percentage in each direction, and note it in your spec.
Recovery, fatigue and grin-through
Stretch is how far the fabric extends. Recovery is how well it returns to its original size, and that’s what customers notice after a few months. Poor recovery shows up as bagging at the knees and seat, or waistbands that lose their grip.
Elastane fatigues with time, heat and chemicals. Once the fibres break down, the fabric can lose its snap or develop small puckers. Grin-through is a related fault: when the fabric is stretched, the base knit or the elastane becomes visible, like a pale sheen through black leggings. Denser knits and well-matched dyeing reduce it.
How to care for spandex fabrics
Elastane is tough in use but sensitive to a few things. Your care label should protect it:
- Heat: high dryer heat and hot irons weaken elastane. Wash cool and air-dry or tumble-dry low.
- Chlorine: chlorine bleach and pool water break down standard elastane. For swimwear, ask for chlorine-resistant elastane or a polyester-based stretch fabric such as PBT.
- Fabric softener: it can coat performance fabrics and reduce wicking, so many activewear brands advise against it.
At the mill, elastane fabrics are heat-set to stabilise their width and shrinkage. Ask for finished, heat-set fabric; unset fabric can shrink and distort after the first wash.
Is spandex sustainable?
Elastane is made from fossil-fuel-based chemicals, and it isn’t biodegradable. The bigger problem is recycling: elastane is almost always blended, and a few percent mixed through cotton, nylon or polyester makes the fabric much harder to recycle fibre-to-fibre.
If sustainability matters to your brand, a few practical steps help:
- Use only as much elastane as the fit needs. A relaxed tee doesn’t need it at all.
- Ask about recycled nylon or recycled polyester for the base fibre; some mills also offer recycled-content elastane.
- Design for durability. Good recovery and a sensible care label keep leggings in use for longer, which matters more than most fibre swaps.
What to specify for stretch fabric in your tech pack
“Nylon/spandex” on its own leaves too much open. Put these in the fabric section of your tech pack:
- Composition: exact percentages, for example 78% nylon, 22% elastane, plus any branded fibre requirement.
- Construction and weight: knit type and finished GSM with a tolerance, commonly ±5%.
- Stretch and recovery: minimum stretch in width and length and maximum growth after stretching, tested to an agreed method such as EN 14704-1.
- Opacity: a squat or stretch test on the sample for leggings and shorts.
- Chlorine resistance: for swimwear.
- Stitching: stretch stitches such as overlock, coverstitch or flatlock, with textured nylon or polyester thread so seams don’t pop.
Patterns for high-stretch garments also need negative ease, meaning the finished garment measures smaller than the body. That’s set during fitting, so expect fit revisions before you approve the pre-production sample. For the full process, see our guide on how to create a tech pack, or have us draw one through our activewear tech pack service.
If you’re ready to produce leggings, sports bras or training tops, our activewear manufacturing service works from 50 pieces per style at a specialist performance facility.
How Fabrickly can help. We source stretch fabrics to your composition, weight and stretch spec, make samples through proto, fit and pre-production stages, and inspect bulk to AQL 2.5 before shipping. Send your tech pack or a sketch through our quote request page for an itemised quote within one business day.
Frequently asked
Q: What is spandex made of?
Spandex is a synthetic fibre made from at least 85% segmented polyurethane. It is spun into fine elastic filaments and blended with fibres such as cotton, nylon or polyester.
Q: Is spandex the same as elastane?
Yes. Spandex and elastane are the same fibre. Spandex is the name used in North America, and elastane is the name used in the UK, the EU and most other markets.
Q: What is the difference between spandex and Lycra?
Lycra is a brand name for spandex, owned by The LYCRA Company. All Lycra is spandex, but not all spandex is Lycra.
Q: What percentage of spandex is good for leggings?
Most leggings use 15–25% spandex, with around 20% being common for gym and yoga styles. Fabric weight and knit density matter just as much for support and opacity.
Q: Does spandex shrink?
Elastane fabrics are heat-set at the mill to control shrinkage. High dryer heat can still damage the fibres and distort the garment, so wash cool and air-dry or tumble-dry low.
Q: Is spandex bad for chlorine?
Yes. Chlorine breaks down standard spandex, so swimwear worn in pools often uses chlorine-resistant elastane or polyester-based stretch fabrics.
— Hasebul, Fabrickly