100Percent Bike Helmet Size Chart

1. Achieve the perfect fit by measuring your head circumference correctly.

2. Watch the video below to see how to measure your head correctly.

3. VIDEO: How To Measure For A Bike Helmet

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4. On the chart below, find the helmet model that you are interested in, then find your head measurement to see which size you need.

100Percent Bike Helmet Size Charts

100Percent Mountain Bike Helmet Size Chart

Model XS S M L XL XXL
Aircraft 53 – 54cm 55 – 56cm 57 – 58cm 59 – 60cm 61 – 62cm 63 – 64cm
20⅞” – 21¼” 21⅝” – 22″ 22½” – 22⅞” 23¼” – 23⅝” 24″ – 24⅜ “ 24¾”- 25¼”
Aircraft Carbon MIPS 53 – 54cm 55 – 56cm 57 – 58cm 59 – 60cm 61 – 62cm 63 – 64cm
20⅞” – 21¼” 21⅝” – 22″ 22″ – 22⅞” 23¼” – 23⅝” 24″ – 24⅜ “ 24¾”- 25¼”
Status 53 – 54cm 55 – 56cm 57 – 58cm 59 – 60cm 61 – 62cm 63 – 64cm
20⅞” – 21¼” 21⅝” – 22″ 22″ – 22⅞” 23¼” – 23⅝” 24″ – 24⅜ “ 24¾”- 25¼”
Trajecta
52 – 56cm 56 – 58cm 58 – 61cm 61 – 64cm

20½” – 22″ 22″ – 22⅞” 22⅞” – 24″ 24″ – 25¼”

100Percent Trail Bike Helmet Size Chart

Model XS-Small S/M L/XL
Altec 50 – 55cm 55 – 59cm 59 – 63cm
19⅝ “- 21⅝ “ 21⅝” – 23¼” 23¼” – 24¾”

100Percent Youth Downhill & BMX

Model Y-Small Y-Medium Y-Large
Status 47 – 48cm 49 – 50cm 51 – 52cm
18½” – 18⅞” 19¼” – 19⅝” 20⅛” – 20½”