A mat looks like the simplest thing in a home gym, and it is. Still, the one number that matters, thickness, pulls in two directions: thicker is kinder to your knees and spine, thinner is steadier under your feet. The right answer depends on what you actually do on it.

Thickness is a trade-off, not a quality score

Mats are sold by thickness in millimetres. Roughly: 1–3 mm is a travel mat that folds small, 4–6 mm is the standard yoga mat, and 10–15 mm is a thick floor-exercise mat. None of these is "better". Foam compresses under a hard part of your body, such as a knee, an elbow or the bones of your spine, so more foam spreads the pressure. But foam also squashes under your feet, which makes it wobble when you stand on one leg or hold a low lunge.

Try it below. Pick what you will mostly do, then slide the thickness and watch the two scores move. These are rules of thumb to build your intuition, not lab measurements.

Match the thickness to what you do

Floor exercises such as planks, crunches and glute bridges put bony points on the ground: elbows, tailbone, spine. A mat in the 8–15 mm range saves those spots. Very thin mats on a hard floor are the usual reason people quit after a few days.

Standing work such as yoga flows, balance practice and stretching on your feet suits something thinner. At 4–6 mm your foot still feels the ground, so you can balance without the mat squashing sideways.

Kneeling work sits in between. If your knees complain on a standard mat, a folded second mat or a thicker one helps. If a knee hurts during an exercise even with padding, that is not a mat problem: stop and check with a doctor or physio.

If you do a bit of everything, a mat around 6–10 mm is a sensible start. Most beginners do not need to own two.

What else to check

• Size. Many mats are about 180 × 60 cm. If you are tall, or you like space to lie flat with your arms out, check the length and width before the thickness.
• Material. PVC mats are cheap and easy to wipe clean. TPE is a lighter, softer plastic. NBR is a dense foam that is usually sold thick. Natural rubber exists too, but it is heavier and often costs more.
• Grip. A textured top surface helps on sweaty hands and feet. A smooth one slides sooner.
• Floor. On carpet, a thick mat can feel unstable. On tile or wood, extra thickness pays off.
• Storage. A thick mat rolls into a bigger tube. In a small space that matters.

What to look for

Under about €15: a basic mat of 6 mm or so is enough to get started. Check the length, and that the surface is not slick.

Around €15–25: this is where you find thicker foam, such as 10–15 mm, and sturdier material. It is the range to look at if you do a lot of floor work.

Above that: you are mostly paying for brand, natural materials or looks. A beginner rarely needs to spend more than this to get a mat that does the job.