TestedHelmetsMeasure your head
- Use a soft tailor's tape. A piece of string and a ruler work too.
- Wrap it around the widest part of your head, about an inch above your eyebrows and just above your ears.
- Keep it level and snug, then read the number in centimeters. Most size charts use centimeters.
- Measure twice to make sure you get the same number.
Size charts vary by brand
There's no standard helmet size. A medium from one brand can cover a different range than a medium from another, and one model's sizes can change between versions. Always use the chart for the exact helmet you want. If you land between two sizes, try both on if you can. You want the one that feels snug before you tighten the dial much.
Some brands sell versions for rounder heads, often called Asia fit or round fit. If regular helmets never sit right on your head, one of those may fit better.
Virginia Tech has tested these fit versions. Lower STAR is better, and you can only compare helmets in the same style.
- Bontrager Starvos WaveCel Asia Fit: Road, STAR 11.115, tested 2021
- Bontrager Starvos Wavecel Round Fit: Road, STAR 11.115, tested 2021
- Trek Ballista MIPS Asia Fit: Road, STAR 11.441, tested 2023
- Trek Solstice MIPS Asia Fit: Multi-sport, STAR 11.933, tested 2023
The fit check
- Position. Put the helmet on level, low on your forehead. The front edge should sit one or two finger-widths above your eyebrows.
- Fit dial. Tighten the dial or fit ring at the back until the helmet stays put when you shake your head, before you buckle the strap.
- Side straps. Adjust the sliders so each pair of straps forms a V just under and slightly in front of your ear.
- Buckle. Center the buckle under your chin, not off to one side.
- Chin strap. Tighten it until no more than one or two fingers fit between the strap and your chin.
- Final check. Open your mouth wide in a big yawn. The helmet should pull down on your head. Then push it back and forth. It shouldn't rock back to show your forehead or slide forward into your eyes.
Signs of a bad fit
- You can see your whole forehead. The helmet is tilted back, so shorten the front straps.
- It slides forward into your eyes. Tighten the back straps or the dial.
- You get a headache or a sore spot on a short ride. The shape doesn't match your head, so try another model or size.
- The dial is at its tightest and the helmet still moves. Go down a size.
- The straps cover your ears or twist. Readjust the sliders and flatten the straps.
Use only the pads that came with the helmet. CPSC warns against adding extra padding or parts the manufacturer didn't include, and against wearing a helmet that doesn't fit.
Pick by score, then by fit
Choose a well-rated helmet that fits securely, because a loose one can shift in a crash. Start with helmets that scored well in your riding style, then keep the one that passes the fit check.
Buying for a child? See kids' bike helmets. Already have a helmet? Check when to replace it.