Your head circumference is a starting point; confirm the final size with the exact helmet on and the strap fastened. The same letter does not guarantee the same fit across helmets.
How to measure
Use a flexible tape without pulling it tight. Shoei's manual places it about 2 cm above your eyebrows and where your ears join your head, passing over the most prominent point at the back. Repeat if the tape moves.
Use the model's chart, not a universal conversion
- Shoei guide: reference chart and what to try between sizes.
- Shark guide: check XXL and the published differences between model families.
- Official AGV chart: use the relevant model group; do not apply MS/ML sizing to the whole brand.
A measurement between ranges does not mean automatically buying the smaller size. Shoei suggests trying the smaller one first, but it still has to pass the fit checks. If one size creates a pressure point and another is loose, try a different model or ask about an authorised fitting.
Shape varies within a brand
We do not label entire brands as round or oval. Assess the model and regional version. Being able to chew gum is not our sizing test: cheek contact, movement and retention are more relevant checks.
Check the fit before deciding
- Position the helmet correctly and fasten the strap. Contact should be firm and even, without pain or pressure points.
- Hold it and gently move it sideways and up/down: your skin should follow it rather than the helmet sliding freely.
- Follow the retention check in the manual; if it can come off with the strap correctly adjusted, do not use it that way. Ask a specialist retailer for help.
- Keep it on for a few minutes and try your usual glasses. A short fitting cannot guarantee comfort throughout a journey.
Before ordering online
Confirm the exact size and version, returns policy and whether you can try it without riding. Do not substitute another size because yours is unavailable. Homologation and price do not replace fit.
Sources checked on 17 October 2026: Shoei selection and wearing manual, Shoei fitting guidance and SHARP fitting guide.
Correction, 17 October 2026: removed the universal conversion chart, whole-brand head-shape labels and chewing-gum test.