Smith Helmet Size Chart

Adult Helmets
Size Regular Fit (in) Regular Fit (cm) Round Contour / Asian Fit (in) Round Contour / Asian Fit (cm)
Small 20.1–21.7 51–55 21.7–23.2 55–59
Medium 21.7–23.2 55–59 23.2–24.8 59–63
Large 23.2–24.8 59–63 24.8–26.4 63–67
X Large 24.8–26.4 63–67 N/A N/A
Holt & Junior Helmets
Size Head Circumference (in) Head Circumference (cm)
Youth Small 18.9–20.9 48–53
Youth Medium 20.9–22.8 53–58
Youth S/M 18.9–22 48–56
X Small 20.5–21.3 52–54
Small 21.3–22 54–56
Medium 22–22.8 56–58
Large 22.8–23.6 58–60
X Large 23.6–24.4 60–62

Round Contour Fit: The adult chart lists head circumference in centimeters for the Regular Fit and the Round Contour / Asian Fit. Smith Round Contour Fit helmet illustration