Giro

Adult Helmets

Helmet Sizing Inches Centimeters
Small 20.50 - 21.75" 52 - 55.5 cm
Medium 21.75 - 23" 55.5 - 59 cm
Large 23 - 24.25" 59 - 62.5 cm
X-Large 24.50 - 25.50" 62.5 - 65 cm

  

Kid's Helmets

Helmet Size Inches Centimeters
Extra Small 19.25 - 20.50" 48.5 - 52 cm
Small 20.50 - 21.75" 52 - 55.5 cm
Medium 21.75 - 23" 55.5 - 59 cm