How to measure
Wrap a soft tape measure around your head about 2.5 cm (1 inch) above your eyebrows, at the widest point. If you wear a balaclava, measure with it on. Take the largest measurement.
Bell
Bell racing helmets size chart
| Size | Head circumference (cm) | Hat size |
|---|---|---|
| 4XS | 51 | 6 3/8 |
| 3XS | 52-53 | 6 1/2 - 6 5/8 |
| XXS | 54-55 | 6 3/4 - 6 7/8 |
| XS | 55-56 | 7 |
| SML | 57-58 | 7 1/8 - 7 1/4 |
| MED | 58-59 | 7 1/4 - 7 3/8 |
| LRG | 60-61 | 7 1/2 |
| XLG | 61-62 | 7 5/8 - 7 3/4 |
| XXL | 63-64 | 7 7/8 - 8 |
| 3XL | 65-66 | 8 1/8 - 8 1/4 |
| 4XL | 67-68 | 8 3/8 - 8 1/2 |
HP / Carbon / Pro line: available only in sizes XXS to XLG.
The cm ranges per size are approximate. Always measure your head circumference, and contact us if you are between sizes.
Other brands: helmet sizing differs per brand (and sometimes per model). Always use the brand's own table below; do not convert sizes between brands.
Stilo
Stilo ST6 / ST5 helmet sizes
| ST6 size | Suggested head circumference (cm) | ST5 equivalent (as published) |
|---|---|---|
| XS 54 | 54 | ST5 XS 54 |
| S 55 | 55 | ST5 S 55 |
| S 56 | (ZERO models only) | – |
| M 57 | from 56 up to 57 | ST5 M 57 |
| L 58 | 58 up to 59 | drivers who comfortably wore ST5 L 59 |
| L 59 | from 59 to 60 | drivers who wore ST5 L 59 with minor pressure points, or ST5 L 60 |
| XL 61 | from 61 up to 62 | ST5 XL 61 |
| 2XL 63 | from 62 to 63 | ST5 XXL 63 |
| 3XL 64 | above 63 to 64 | ST5 XXL 64 |
Stilo ST5F range available sizes: XS 54, S 55, M 57, L 59, L 60, XL 61, 2XL 63, 3XL 64 (the number is the head circumference in cm for that shell size).
Source: Stilo official ST5/ST6 size comparison and ST5F range page (stilo.it), retrieved 2026-10-26.
Arai
Arai CK-6 (kids kart helmet)
| Size | XXS | XS | S | M | L |
|---|---|---|---|---|---|
| Head (cm) | 50-51 | 52-53 | 54-56 | 57-58 | 59 |
Source: Arai Americas (official distributor), CK-6 page, retrieved 2026-10-26.
Arai SK-6 (kart helmet)
| Size | XS | S | M | L | XL |
|---|---|---|---|---|---|
| Head (cm) | 53-54 | 55-56 | 57-58 | 59-60 | 61-62 |
Source: per importer Arai Finland (arai.fi), SK-6 page, retrieved 2026-10-26.
Arai GP-6S
No verified size chart is available for the GP-6S. Please contact us and we will help you choose the right size.
Sizes are indicative and may vary from model to model.
Unsure about your size? WhatsApp or email us and we will help you choose.