This calculator helps you quickly determine the correct helmet size based on your head circumference in centimetres or inches. It can be used to choose cycling, skiing, skating, and snowboarding helmets for both adults and children.
Calculator
How to Measure Your Head Circumference Correctly
Your head circumference is the most important measurement for choosing the correct helmet size. An error of even 1 cm can lead to the helmet pinching or sliding around while riding.
What you need. Use a soft tape measure or a piece of string that can be measured with a ruler afterwards. A rigid ruler or metal tape measure is not recommended because it does not follow the natural shape of your head.
How to measure. Wrap the tape measure around your head, passing over the widest part of your forehead (about 2–3 cm above your eyebrows) and the widest part of the back of your head. The tape should sit snugly without being too tight. Take the measurement twice and use the larger result.
Tip. Ski helmets are often worn over a thin balaclava or beanie, so include this extra layer when measuring if applicable.
Helmet size chart
| Size | Adult | Kids | ||
|---|---|---|---|---|
| cm | inches | cm | inches | |
| XXS | — | — | 46–48 | 18.1–18.9 |
| XS | 51–53 | 20.1–20.9 | 48–50 | 18.9–19.7 |
| S | 53–55 | 20.9–21.7 | 50–52 | 19.7–20.5 |
| M | 55–57 | 21.7–22.4 | 52–54 | 20.5–21.3 |
| L | 57–59 | 22.4–23.2 | 54–56 | 21.3–22.0 |
| XL | 59–61 | 23.2–24.0 | 56–58 | 22.0–22.8 |
| 2XL | 61–63 | 24.0–24.8 | — | — |
| 3XL | 63–65 | 24.8–25.6 | — | — |
Frequently Asked Questions (FAQ)
What do the numbers on helmets from AliExpress and Chinese sites mean?
Some manufacturers — particularly Chinese and Korean ones — label helmet sizes with a number, such as «56», «58», or «60». This is not a different sizing system — the number simply indicates the recommended head circumference in centimetres. A helmet labelled "58" is generally intended for a head circumference of approximately 58 cm and typically falls within the size range that includes 58 cm.
The same applies to helmets marked «55–58» or «57–62 cm» — that range is simply your target head circumference. The calculator shows exactly this range in the results, so you can compare it directly with the label on the helmet.
What if my measurement falls on the boundary between two sizes?
If your head circumference falls exactly on the boundary between two sizes (for example, exactly 57 cm — between M and L), it is recommended to choose the larger size. Helmet padding often compresses slightly over time, making the fit a little roomier, but a tight helmet is uncomfortable during long sessions and may cause pressure on the head. Many modern helmets also feature an adjustment system (a dial or strap at the back) that allows fine-tuning the fit by ±1–2 cm.
Do different brands use different size charts?
The standard helmet size ranges (XS–3XL) are broadly similar across most manufacturers — Bell, Giro, POC, Uvex, Alpina, Fischer, MET, etc. Minor differences may exist in the helmet shape (round, oval), but not in the correspondence between size and circumference. Always check the specific brand's size chart when buying an expensive helmet or if you have an unusual head shape.
Can one helmet be used for different sports?
Helmet sizing is generally consistent across different sports. However, the construction varies by sport: a cycling helmet is light and well-ventilated, a ski helmet is warm and usually covers the ears, and a roller/skate helmet is designed to withstand side impacts. You can use this calculator to find your size, but choose a helmet designed for your specific sport.
How long can a helmet be used, and does it need to be replaced after a crash?
Most manufacturers recommend replacing a helmet every 3–5 years even without visible damage, as materials gradually lose their impact-absorbing properties. After any significant impact, the helmet should be replaced immediately, even if it looks undamaged. The EPS foam liner is designed to absorb impact energy by deforming during a crash, which prevents it from providing the same level of protection afterward.