What is Spandex anyway?

Written By Wes Lentz

If you’ve ever slipped into a pair of comfy boxer briefs or a fitted turtleneck that hugs just right, you’ve probably felt the magic of Spandex. But what is Spandex, really? Is it the same as Elastane? And why does it make such a difference in men's knitwear?

Man exercising in a purple spandex outfit

Let’s break it down:

So, What Is Spandex?

Spandex is a synthetic fiber known for its exceptional stretch. It can expand up to five times its original length and snap right back without losing shape. That’s why it’s a go-to for underwear, activewear, and anything that needs to move with your body.

Fun fact: “Spandex” is actually an anagram of “expands.” Clever, right?

Spandex: The Fiber vs. The Fabric

Let’s clear up a common mix-up: Spandex is a fiber, not a fabric.

When we say “Spandex,” we’re talking about the stretchy synthetic thread that gets blended into other fibers—like cotton, rayon, or polyester—to create fabrics that stretch and recover. You won’t find a fabric made of 100% Spandex; it’s usually 3–10% of the total fiber content, just enough to give the fabric that signature snap-back stretch.

So when someone says “Spandex fabric,” they usually mean a fabric containing Spandex—not a fabric made entirely from it.

Elastane vs. Spandex vs. Lycra: Are They the Same?

Yep, they’re the same fiber, just different names depending on where you are. In the U.S., we say “Spandex.” In Europe, it’s “Elastane.” If you’re shopping fabric online, you might also see “Lycra,” which is a brand name for a type of Elastane made by The LYCRA Company.

So whether it’s labeled Spandex, Elastane, or Lycra, it’s all stretchy goodness.

How Is Spandex Made?

Spandex is made through a process called solution dry spinning. Without getting too technical on you, it involves:

  • Creating a polymer (usually polyurethane)

  • Forcing it through a spinneret to form fibers

  • Solidifying those fibers with heat

  • Winding them into yarns that can be blended with other fibers like cotton, rayon, or polyester

The result? A stretchy, durable fiber that plays well with others.

Why Spandex Makes Knitwear and Knit Fabric Better

Here’s where things are ideal for those of us that sew. Adding Spandex to knit fabrics gives them:

  • Better recovery: No saggy knees or stretched-out necklines

  • Improved fit: Think body-hugging without being restrictive

  • Durability: Spandex helps garments hold up to wear and washing

  • Comfort: It moves with you, not against you

For men’s underwear, shirts, and turtlenecks, this means a smoother silhouette, fewer wrinkles, and a garment that feels like it was made just for you (because it was, thanks to your pattern!).

The Hulk stretching a pair of underwear saying ‘Spandex is your best friend’

Common Knit Fabrics That Contain Spandex

Here are a few popular knit types you’ll see in men’s underwear, shirts, and turtlenecks, and more:

  • Cotton-Spandex Jersey: Soft, breathable, and stretchy. Great for everyday basics and fitted tees.

  • Rayon-Spandex Jersey: Drapey and smooth with a bit of sheen. Ideal for layering pieces like turtlenecks.

  • Modal-Spandex: Silky and luxe with excellent recovery. A favorite for premium underwear.

  • Bamboo-Spandex: Naturally antibacterial and moisture-wicking. Perfect for sensitive skin.

  • Poly-Spandex (Athletic Knit): Durable and slick, often used in performance wear or compression garments.

  • French Terry with Spandex: Cozy with a looped back, but still stretchy. Great for loungewear or sweater vests.

Each of these blends behaves a little differently, so it’s worth swatching or testing before committing to a full project. But if your pattern calls for stretch, checking that fiber content for Spandex is key.

Where to Shop for Spandex Fabrics

Looking to stock up for your next project? Here are a few online shops that carry quality Spandex blends:

Always check the fiber content—5–10% Spandex is usually the sweet spot for everyday knitwear. If I had to choose between a knit fabric that does contain Spandex and one that does not, I’d always opt for the one that DOES contain Spandex because of the improved recovery, durability, and comfort of the finished garment.

Whether you're drafting a new pattern or tweaking a fit, understanding Spandex helps you make smarter fabric choices. It’s one of those behind-the-scenes heroes that makes your handmade garments feel professional, wearable, and so satisfying.

Looking for more information?

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Wes Lentz
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