Your riding helmet is the most important safety equipment you own — but it only protects if it fits correctly. A certified helmet worn too loose, too high, or the wrong shape gives a dangerous false sense of security. The good news: fitting is straightforward once you know what to check. This guide covers how to measure, the fit tests that matter, why certification is non-negotiable, and the firm rules around second-hand helmets and replacement.
Get fitted in person if you can. Head shapes vary, and helmets fit differently by brand. A trained fitter at a tack shop will measure you and check the fit properly — well worth it for your most important piece of safety kit. Use the checks below whether fitting in person or assessing one you’ve bought.
1. Measure your head
Wrap a soft tape measure around the widest part of your head — roughly 2cm above your eyebrows and ears, around the back. This circumference (in cm) gives your starting size, but treat it only as a guide: you must try the helmet on, because shape matters as much as size.
2. The fit checks that matter
- Level and low. The helmet should sit level on your head, with the front edge about 2cm above your eyebrows — not tipped back exposing the forehead.
- Snug all round. It should feel firm and even around the whole head, with no pressure points and no gaps. It shouldn’t be painfully tight.
- No rocking or sliding. With the harness undone, gently move the helmet front-to-back and side-to-side — your scalp should move with it, not the helmet sliding over your skin.
- The tip test. Tip your head forward; the helmet should stay put, not fall off.
3. Adjust the harness
Once the shell fits, fasten the harness so the chin strap is snug — you should fit about one finger between strap and chin. The straps should sit comfortably around (not over) the ears, forming a “V”. A correct harness keeps the helmet in place; it cannot make a wrong-sized shell fit.
4. Certification is the baseline
Only consider helmets meeting a recognised standard — ASTM/SEI (US), PAS 015 or VG1 (UK/EU), or Snell. Look for the label or sticker. MIPS adds rotational-impact protection and is a worthwhile feature. An uncertified or fashion “helmet” offers no reliable protection regardless of fit. See best riding helmets for certified picks.
The firm rules
Never compromise on these: Buy new, never second-hand — you can’t see prior impact damage. Replace after any fall or hard knock, even if it looks fine, because the protective liner is designed for a single major impact. And replace every few years regardless, as materials degrade. A helmet is cheap insurance for your brain.
What to skip
Don’t buy a helmet to “grow into.” A loose helmet shifts and won’t protect — size it to fit now, especially for children. Don’t rely on the chin strap to hold a too-big helmet on — the shell itself must fit. And don’t keep wearing a helmet after a fall to save money; replace it.
The bottom line
A correctly fitted helmet sits level and low, hugs your head evenly with no rocking, and has a snug one-finger chin strap. Buy certified and new, get fitted in person where possible, and replace after any fall or every few years. Fit matters more than price — a well-fitted mid-range helmet protects better than an ill-fitting premium one.
Ready to choose? See our best riding helmets, and complete your safety setup with boots that have a defined heel and safety stirrups.