Why Use This Calculator?
A helmet that doesn't fit doesn't protect — the difference between a size M and L is whether the shell manages an impact or slides off-line. This calculator converts one tape measurement into your size against the industry-standard chart.
It auto-detects whether you measured in inches or centimeters, and the same chart governs bike, motorcycle, and snow helmets — though shells vary by brand, so treat the letter as your starting size, not a guarantee.
How It Works
- Wrap a soft tape above the eyebrows, around the fullest part of the head.
- Enter the circumference — inches or centimeters both work.
- Try the recommended size first, but always confirm with the brand's own chart.
Frequently Asked Questions
How does a motorcycle helmet size chart work?
Motorcycle, bike, and snow helmets share the circumference-based chart: roughly S under 21.75 inches, M to 23.25, L to 24.5, XL to 26. Motorcycle helmets fit very snug — it should feel almost too tight at first.
How do I measure my head for a helmet?
Use a soft tape above the eyebrows and around the fullest point of the back of the head. Measure two or three times — a half inch of tape slip changes the size.
What if I'm between helmet sizes?
Size down for rounder heads and helmets with thick pads, and check the brand's head-shape guidance (long oval vs round oval). A helmet should press evenly, with no single hotspot.
Tips & Things to Watch
- Replace any helmet after a significant crash — protection is single-use.
- Helmets break in slightly; it should be snug on day one, not day thirty.
- Never buy used helmets — you can't see compressed foam.