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What Is Spandex (Elastane)?

Every legging tag lists a spandex, elastane, or Lycra percentage — and confusingly, those are all the same thing. That number quietly determines how a legging feels and performs. Here is what the stretch fiber actually is and how much of it you want.

By Sweat the Details Editorial Team · Published · Updated

Note: This is a plain-English explainer. We decode how this material or spec is described by manufacturers; we do not lab-test, and figures cited are industry-standard descriptions rather than our measurements.
The short answer: Spandex, elastane, and Lycra are three names for the same stretch fiber (Lycra is a brand name). The percentage tells you how much stretch and recovery a fabric has. Roughly 19–25% gives soft, flexible leggings; less means firmer or stiffer.

Spandex, Elastane, Lycra: All The Same Fiber

This trips people up constantly. Spandex (the common US term), elastane (the European term), and Lycra (a trademarked brand of elastane, like Kleenex for tissues) are all the same synthetic elastic fiber. When a legging says "19% Lycra" and another says "19% elastane," they are describing the same thing. Lycra just signals the brand paid for a recognized, quality-controlled version.

What The Percentage Tells You

The spandex percentage is the single best predictor of how a legging feels. The rest of the fabric is usually nylon or polyester (the durable base), and the spandex is what adds stretch and snap-back. Roughly 19–25% spandex is the sweet spot for soft, flexible leggings like a Lululemon Align or its dupes — enough stretch to move with you and recover its shape. The famous CRZ Butterluxe is 19% Lycra; that number is why it feels the way it does.

How Much Stretch You Actually Want

More spandex is not automatically better — it depends on the job. A higher spandex ratio in a soft knit means a flexible, low-compression, flowing legging, ideal for yoga and lounge. For firm, holding compression (lifting, running), the construction and a denser knit matter more than just cranking up the spandex. Too little spandex and a legging feels stiff or loses shape; too much in the wrong knit and it can feel flimsy. Match the fabric to the movement — see best leggings by workout.

Why Spandex Needs Care

Heat is spandex's enemy. High dryer heat breaks down elastane over time, which is why leggings lose their stretch and start to sag or pill. Washing cold and hanging or low-heat drying dramatically extends a legging's life — this is true whether it is a $30 dupe or a $100 Align. The fiber is the same; the care determines how long it lasts.

FAQ

Is spandex the same as elastane and Lycra?

Yes, all three are the same synthetic stretch fiber. Spandex is the common US name, elastane is the European name, and Lycra is a trademarked brand of elastane. When a garment lists any of them, it is describing the same stretch component.

How much spandex should leggings have?

Roughly 19 to 25 percent is the sweet spot for soft, flexible leggings that stretch and recover shape, like a Lululemon Align or its dupes. The exact ideal depends on the fabric and intended use; firmer compression leggings rely on construction as much as the spandex percentage.

Does more spandex mean better leggings?

Not necessarily. More spandex means more stretch, which suits soft, low-compression yoga leggings, but firm compression for lifting or running depends more on knit density and construction. The right amount depends on what you use the legging for, not simply maximizing the percentage.

Why do leggings lose their stretch?

Heat degrades spandex over time, so high dryer heat is the main culprit behind leggings that sag, bag out, or pill. Washing in cold water and hanging or low-heat drying preserves the elastane and significantly extends how long leggings keep their shape.

Learn more: nylon vs polyester in activewear · best Align dupes
See it in our reviews: CRZ Yoga Butterluxe · HeyNuts · all legging reviews