Youth Motocross Helmet Size Chart | Measuring Your Child’s Fit

Every motocross parent hears the same advice: don’t guess the size. Before buying any gear, checking a youth motocross helmet size chart is the single most important step for keeping a young rider safe. The problem is that Fox, GLX, and other brands each use their own measurements, so a youth medium from one company may fit tighter than a small from another. This article walks through exactly how to measure, compares the two most common youth charts side by side, and explains what a proper fit actually feels like so you get it right the first time.

How Do You Measure a Child’s Head for a Motocross Helmet?

Use a soft cloth measuring tape — the kind used for sewing — and wrap it around the widest part of the head, about one inch above the eyebrows and just above the ears. Keep the tape level across the forehead and around the back of the skull, snug but not compressing the scalp. Record the measurement in both inches and centimeters. Most youth charts list both, and one may align more clearly with a specific brand’s numbers. Measure at least twice and use the larger reading if the two differ slightly.

Common mistake: placing the tape too low across the forehead instead of above the eyebrows. That gives a smaller reading and leads to a helmet that sits too high and exposes the forehead. The correct measurement should track the head’s widest circumference, which is almost always at the brow line.

Youth Helmet Sizing: Charts for Fox and GLX

The two most widely available youth motocross helmet size charts come from Fox Racing and GLX. They overlap at the smaller sizes but diverge at the larger end — a perfect example of why you must use the specific chart for the helmet you are buying rather than a generic one.

Notice that a Fox youth Large (up to 52 cm) and a GLX youth Medium (also up to 52 cm) cover the same head circumference. If you measure your child at 51 cm, either size could work — but the shape and padding of each specific model may make one a better fit. That is why the measurement is only the starting point. For a list of highly rated models that match these sizing ranges, check out our roundup of the best youth motocross helmets tested for safety and comfort.

If you are shopping for a specific brand, Fox’s official helmet fit guide provides the most current sizing for their youth models. GLX publishes its own chart on its site, and the two should never be used interchangeably.

What to Check After Sizing the Helmet

A correct measurement on paper still needs a real-world fit test. Put the helmet on the child and fasten the chin strap. The helmet should sit level on the head — not tilted back or forward — and the front edge should rest about one finger-width above the eyebrows. When the child shakes their head gently, the helmet should move with the head, not shift independently.

Check for pressure points or hot spots. A snug fit is correct and safe. A painful pinch in any one spot means the shape or size is wrong, regardless of what the chart says. Some youth models include removable cheek pads or extra head liners that allow minor adjustments within the same shell size. If the helmet rocks forward or back with hand pressure, the size is too large. A helmet that leaves deep red marks after a few minutes of wear is too small. The sweet spot is consistent, even pressure across the whole head with no isolated discomfort.

FAQs

Should I buy a size up so my child grows into the helmet?

No. A motocross helmet that is too large shifts during a ride and offers dramatically less protection in a crash. Buy the size that fits properly now and plan to replace the helmet as the child grows.

What if my child’s measurement falls between two sizes on the chart?

Choose the larger size and use the cheek pads or liner to take up the extra space if the model supports it. A slightly oversized shell with proper padding is safer than one that is too small and creates pressure points.

Do all youth motocross helmets use the same size chart?

No. Each manufacturer sets its own sizing, and the same head circumference can correspond to different labeled sizes across brands. Always reference the specific helmet’s chart rather than a generic youth size guide.