Is It Really 100% Cotton? How to Check What Your Clothes Are Made Of

You pick up a shirt, and the label says 100% cotton. It feels like cotton. But somewhere between the rack and the register, a little question sneaks in: is it really?

It’s a fair question, and you have more ways to answer it than you might think. You can check fabric content at home with a few quick tests, and a lab can settle the rest. Knowing which is which makes all the difference between checking and guessing.

How Often Are Clothing Labels Wrong?

More often than you might expect, though not as often as the internet sometimes suggests.

In a 2026 EU inspection campaign, 37% of tested garments were mislabeled. And a 2019 Dutch government study that scanned more than 10,000 used garments found fiber labels likely to mislead in 41% of cases.

But before those numbers send you rethinking your whole closet, some reassurance: most labels are honest, and simple claims like 100% cotton generally hold up better than complicated blends. Still, a label is a claim, not a guarantee, so it’s worth knowing how to check one.

How Can You Check Fabric Content at Home?

A few simple tests can tell you something real about a fabric. None of them can give you an exact percentage, but each one can raise (or lower) your confidence in the label.

The feel test. Cotton generally feels matte and dry, and it softens when you crush it in your hand. Polyester tends to feel smoother and slicker, with a slight spring when you pinch and release it. Keep in mind that some synthetics are designed to feel like cotton, and they’re quite good at it.

The water drop test. Cotton absorbs a drop of water quickly and darkens as it spreads. Polyester tends to hold the drop up as a bead. Try this somewhere hidden, like an inside hem. Water-repellent finishes can defeat this test, though, and so can residues on brand-new clothing.

The wrinkle test. Ball up a section of fabric, squeeze for ten seconds, and let go. Cotton creases and holds those creases, while polyester springs back. If a garment labeled 100% cotton bounces back nearly flat, it may be blended, or it may have a wrinkle-resistant finish. This test can’t tell you which.

What About the Burn Test?

If you’ve searched for fabric identification online, you’ve probably run into the burn test: burning a small sample of fibers to see how they behave. Cotton burns like paper and leaves a soft ash, while synthetics melt and leave a hard bead.

We’d suggest leaving this one to the professionals. It involves an open flame and fumes, and it’s less conclusive than it sounds. The burn test can’t tell cotton apart from other plant-based fibers like viscose or linen, which burn the same way. And it can’t tell you percentages, which is exactly what the label is claiming.

Why Do Exact Percentages Need a Lab?

Every home test answers a yes-or-no kind of question: absorbent or not, springy or not, synthetic or not. The label makes a numerical claim, and numbers require measurement.

Textile laboratories use standardized methods, like the ISO 1833 series, to measure fiber content. In simple terms, an analyst uses a solvent that dissolves one fiber type while leaving the other intact, then weighs what remains. The difference reveals each fiber’s share of the fabric.

It’s precise, but it destroys the sample and costs real money, which is why the whole market hasn’t already been tested and published somewhere.

How Can a Fabric Scanner App Help?

This is where Lynen comes in. Lynen is a fabric scanner app that works like a clothes material checker: scan a garment, and Lynen compares the label’s claim against independent lab results when verification is available.

We commission accredited laboratories to run the standard testing methods on real garments, and we publish what comes back, including the many results that match the label. When we haven’t checked something yet, we say so, and the testing queue is shaped by what people ask us to check.

So, is it really 100% cotton? Often, yes! A single-fiber claim is one of the stronger claims you’ll find on a label. And with a few quick checks at home, plus independent verification when you want certainty, you can shop with much more confidence than the label alone provides.

Frequently Asked Questions

How can I tell if a garment is really 100% cotton?

A few home checks can help: cotton absorbs water quickly, feels matte rather than slick, and holds wrinkles after you squeeze it. For an exact fiber percentage, though, only laboratory testing can confirm what a fabric contains.

Does the burn test really identify fabric?

Only partly. Burning fibers can hint at the fiber family, but it can’t tell cotton apart from other plant-based fibers like viscose or linen, and it can’t measure percentages. It also involves an open flame, so we suggest leaving it to the professionals.

How often are clothing labels wrong?

Labels sometimes mislead. A 2026 EU inspection campaign found 37% of tested garments mislabeled, and a 2019 Dutch government study of used garments found fiber labels likely to mislead in 41% of cases. Simple claims like 100% cotton generally hold up better than blends.