Every KASK chart below is verified against the brand's official sizing, and all numbers are head circumference — a body measurement, in cm and inches.
KASK fit — the short version
Chart applies to: Protone, Protone Icon, Mojito³, Valegro, Utopia, Utopia Y, Wasabi, Elemento.
The 52–56 cm range overlaps between S and M intentionally. Riders with rounder / wider heads typically prefer S; riders with narrower / longer heads typically prefer M.
KASK's Octo Fit dial system covers the full range within each size band.
TT helmets (Bambino Pro, Mistral) use a tighter chart: M = 55–58 cm, L = 59–62 cm. Check the per-product page for Bambino Pro.
Mojito X / X Peak adds an XL band (63–64 cm). Modern Mojito³ does not.
Helmets
S — head circumference 50–56 cm (19.7–22.0 in)
M — head circumference 52–58 cm (20.5–22.8 in)
L — head circumference 59–62 cm (23.2–24.4 in)
Common questions
Which KASK helmet size am I? Measure your head circumference: S 50–56 cm, M 52–58 cm, L 59–62 cm. The 52–56 cm overlap between S and M is intentional — rounder or wider heads typically prefer S, narrower or longer heads typically prefer M, and KASK's Octo Fit dial system covers the full range within each band.
Do KASK TT helmets fit the same? No. The TT helmets (Bambino Pro, Mistral) use a tighter chart: M 55–58 cm, L 59–62 cm — check the per-product page for Bambino Pro. Mojito X and X Peak add an XL band (63–64 cm); the modern Mojito³ does not.
These charts also live on every KASK product page on enroute.cc, and our team fits KASK helmets daily in the Vancouver shop — ask us anything.