Between sizes? Go down.

Most sports headbands come in one size. Ours come in three — S, M, and L — and that choice began with a pattern we kept seeing in our review data at home in Korea.

When fit went wrong, it was rarely because the band was too small. Far more often it was too loose. People weren't squeezing into our headbands — they were slipping out of them.

That pattern changed how we build and how we recommend.

Why loose is the common failure

A band that is slightly tight announces itself in minutes, so people size up to be safe. But knit stretches and warms with wear. A band that felt right in the mirror loosens mid-run, while a band that felt snug settles into place. The error runs in one direction — so our guidance runs in one direction too: if you're between sizes, go down.

How to measure

Wrap a soft tape around your head where you actually wear a band — across the forehead, above the ears. Measure snug, not tight. If you pull the tape, you'll pick a size too large. You'll find the full size chart on every product page.

Why we bother

"One size fits all" really means one size fits the middle. Heads aren't one size, and a band that fits is the difference between gear you forget and gear you fight. That is the whole idea behind TempoKeeper — support for an active life that never reminds you it's there.