GMAX Helmet Size Chart | Adult & Youth Sizing

GMAX helmet size chart showing head circumference in inches and centimeters for adult and youth sizes, with a how-to-measure head diagram and fit tips.

GMAX Helmet Size Chart

Adult Helmets

Size Head (in) Head (cm)
XXS 20 1/16 – 20 7/16 51 – 52
XS 20 7/8 – 21 1/4 53 – 54
S 21 5/8 – 22 55 – 56
M 22 7/16 – 22 13/16 57 – 58
L 23 1/4 – 23 5/8 59 – 60
XL 24 – 24 3/8 61 – 62
2XL 24 13/16 – 25 63 – 64
3XL 25 5/8 – 26 65 – 66
4XL 26 3/8 – 26 3/4 67 – 68

Youth Helmets

Size Head (in) Head (cm)
YS 19 5/16 – 19 11/16 49 – 50
YM / XXS 20 1/16 – 20 7/16 51 – 52
YL / XS 20 7/8 – 21 1/4 53 – 54

How to Measure

Measurement How to measure
Head Wrap a soft tape around your head just above your eyebrows and around the back of your head. Find the closest size in the chart; head shapes vary, so treat it as a starting point.

Fit

Check What to look for
Crown The helmet should feel snug with even pressure all around. Push it forward; if you can fit more than a fingertip between the helmet and your forehead, try a smaller size.
Cheek pads They should feel snug, since they break in over time. If a smaller size fits your crown but is tight on your face, try thinner cheek pads.
Roll-off test With the chin strap unfastened, the helmet should grip the back of your head and not roll forward. If it rolls, try a smaller size or a different model.
Mirror check The brow of the helmet should sit just above your brow bone, and the cheek pads should stay against your face when you move the chin bar side to side.

Notes: Sizing is provided by the manufacturer. GMAX does not guarantee a perfect fit.