A youth ATV helmet size chart from the specific helmet brand you’re buying is the only reliable way to size your child, because sizes vary between manufacturers and even between models from the same brand.
Using age alone to pick a youth ATV helmet is the most common mistake parents make, and it nearly always results in a loose or tight helmet that won’t protect properly. The correct approach is simple: measure your child’s head circumference, then compare that number to the exact chart for the helmet you plan to buy. Here’s exactly how to measure and what to look for when sizing a young rider.
How To Measure Head Circumference For A Youth Helmet
You need a soft cloth measuring tape — the kind used for sewing — or a piece of string and a ruler. A metal tape measure won’t bend around the head accurately. Place the tape just above the eyebrows and just above the tops of the ears, wrapping around the widest part of the head. Keep it snug but not tight, and record the measurement in both centimeters and inches. Measure two or three times and use the largest reading for accuracy.
- Remove ponytails, thick hair clips, or any hair accessory before measuring — they add circumference and will change the fit.
- Write down the measurement, then find the matching size on the brand’s own size chart, not a generic one.
Actual Youth ATV Helmet Size Ranges (Brand-Specific)
No single universal chart covers all youth ATV helmets. A Youth Small from one brand may be 49–51 cm, while another brand calls that same range Youth X-Small. The two examples below show how much sizes shift between manufacturers — this is exactly why you must check the chart for the exact helmet model.
| Brand/Chart Type | Youth Size Label | Head Circumference |
|---|---|---|
| Common manufacturer style | Youth X-Small | 47–49 cm / 18.5–19.3 in |
| Common manufacturer style | Youth Small | 49–51 cm / 19.3–20.1 in |
| Common manufacturer style | Youth Medium | 51–53 cm / 20.1–20.9 in |
| Common manufacturer style | Youth Large | 53–55 cm / 20.9–21.3 in |
| 100% Youth Helmets | S | 47–48 cm |
| 100% Youth Helmets | M | 49–50 cm |
| 100% Youth Helmets | L | 51–52 cm |
FOX Racing’s fit guide agrees with the measurement method above — a soft tape above the eyebrows and ears, then compare to the product page chart. The 100% Youth Helmet Size Guide lists specific ranges for S, M, and L. When you compare the best youth ATV helmets, keep each brand’s chart handy because a 50 cm head may be a Medium in one and a Small in another.
What To Do If The Measurement Falls Between Sizes
Several consumer guides recommend choosing the smaller size for a snugger fit, but this is guidance rather than an official standard from helmet manufacturers. A helmet that is slightly snug will usually break in over the first few rides as the padding compresses; a helmet that is too loose will never become safe. The final call is a judgment based on whether the measurement is closer to the top or bottom of the nearest size range.
The Shake Test And Final Fit Check
Once the helmet is on and strapped, do these checks:
- Position: The helmet should sit level and square on the head, covering the forehead without blocking upward vision. It should not tilt back or forward.
- Shake test: Have the child shake their head side to side and up and down. The helmet should not wobble, slide, or shift more than a tiny amount.
- Chin strap: The strap should be snug. One guide says one finger should fit between the strap and chin; another says two fingers for a general child helmet rule. Either way, the strap must prevent the helmet from lifting off the head.
- Side straps: On some youth fit guides, the side straps should form a V shape below each ear. Adjust the strap connectors if needed.
Buying a bike helmet or motorcycle helmet and assuming it fits the same as an ATV helmet is a mistake — use the chart for the exact helmet model and its intended use. If the helmet fails the shake test or pinches anywhere, exchange it before the first ride.
FAQs
Can I use age instead of head measurement for sizing?
No. Age is an unreliable guide because children’s head growth varies widely. Two seven-year-olds with different growth rates could need different helmet sizes entirely. Always measure the head circumference.
What if my child is between sizes on the chart?
The general guidance is to choose the smaller size for a snug fit, though this is not an official manufacturer rule. A slightly snug helmet will break in; a loose one will not become safe. If the measurement lands exactly in the middle of the gap, try both sizes if possible.
Should I buy from a brand that lists its sizing online?
Yes, and it’s strongly recommended. FOX Racing, 100%, and most major ATV helmet brands publish their fit guides on their product pages. A brand that hides its size chart is a brand making sizing harder than it should be.
References & Sources
- FOX Racing. “Helmet Fit Guide.” Official measurement and sizing instructions for FOX helmets.
- 100%. “Youth Helmet Size Guide.” Brand-specific youth size ranges for S, M, and L helmets.
- MotoSport. “Dirt Bike Helmets for Kids Buying Guide.” Consumer advice on measuring and fitting youth dirt bike and ATV helmets.