Find the right bike helmet size for your child
Measure head circumference or use age — instant size recommendation so the helmet fits safely.
How old is your child?
⚠️ Between sizes? Try both on — the snugger fit is safer. A helmet should not wobble or tip forward.
Recommended size
Kids
54–57 cm · 21.3–22.4"
Ages 5–9
The most common kids' size — widest brand selection. Many brands offer MIPS at this size.
See helmets in this sizeAll helmet sizes at a glance
Click any row to see that size in the tool above.
| Size | Head circumference | Age (approx) | Best for | Reviews |
|---|---|---|---|---|
| XS — Infant | 44–50 cm · 17.3–19.7" | 1–3 yrs | First helmet, very young toddlers | See picks → |
| S — Toddler | 50–54 cm · 19.7–21.3" | 3–5 yrs | Balance bike riders | See picks → |
| M — Kids | 54–57 cm · 21.3–22.4" | 5–9 yrs | Most popular kids' size | See picks → |
| L — Youth | 57–61 cm · 22.4–24" | 8–12 yrs | Older kids & pre-teens | See picks → |
| XL — Teen | 61–65 cm · 24–25.6" | 12+ yrs | Teens & larger heads | See picks → |
* Sizes are a general guide. Always measure — head shape varies between brands. Try before you buy when possible.
How to measure your child's head circumference
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1
Use a flexible tape measure (or a piece of string you measure against a ruler). A rigid ruler won't wrap around the head accurately.
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2
Wrap the tape around the widest part of the head — about 2 cm (¾") above the eyebrows, above the ears, and around the largest part of the back of the head.
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3
Keep the tape level and snug — not tight enough to press in, but with no slack. Take the reading in centimetres for the most accurate result.
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4
Enter the number above. If you land between sizes, always try both and choose the snugger fit — a loose helmet moves in a crash and reduces protection.
The two-finger rule: Once the helmet is buckled, you should be able to fit two fingers between the chin strap and your child's chin — no more, no less. The helmet should sit level, two finger-widths above the eyebrows.