Is it time to replace your race suit? Let’s get you track-ready. Kart helmet sizing is model by model rather than brand by brand. Sparco alone run six different ladders across their kart range, and none of them matches their car helmet ladder. The good news is that every size on this site carries the head measurement inside the size name, so you can ignore the letter completely.
Measure the head
The homologation decides how big the helmet goes
This is the thing that catches parents out. Snell-FIA CMR is the junior standard and every CMR helmet we stock stops at around 59 cm, because it is designed for a child. If your driver measures more than that, a CMR helmet does not exist in their size and you need a CMS, a Snell K or an FIA 8878 helmet instead. Check which your series accepts before you shop.
| Helmet | Homologation | Size range |
|---|---|---|
| Snell-FIA CMR 2016, the junior standard | ||
| Bell KC7-CMR | Snell-FIA CMR 2016 | 54 – 59 cm |
| Bell KC7-EV CMR | Snell-FIA CMR 2016 | 51 – 59 cm |
| Stilo ST5 CMR | Snell-FIA CMR 2016 | 54 – 59 cm |
| Stilo ST6 CMR Zero and Lite | Snell-FIA CMR 2016 | 53 – 59 cm |
| Sparco Stealth CMR | Snell-FIA CMR 2016 | 53 – 59 cm |
| Sparco GP KF-4W CMR | Snell-FIA CMR 2016 | 54 – 59 cm |
| Arai CK-6 | Snell-FIA CMR 2016 | 51 – 60 cm |
| Stilo ST5F N KRT | Snell-FIA CMR 2016 | 54 – 64 cm |
| Snell-FIA CMS 2016, the same shell for seniors | ||
| Bell KC7-EV CMS | Snell-FIA CMS 2016 | 51 – 59 cm |
| Bell Carbon KC7-CMR | Snell-FIA CMS 2016 | 52 – 59 cm |
| Senior kart standards | ||
| Stilo ST6 KRT | FIA 8878-2024, Snell K2025 | 54 – 64 cm |
| Bell RS7-K | Snell K2020 | 54 – 61 cm |
| OMP GP-R K | Snell K2020 | 52 – 63 cm |
| Arai SK-6 | Snell K2015 | 53 – 62 cm |
| Sparco Air KF-7W, Sky KF-5W | Snell K2015 | 53 – 62 cm |
| ECE 22-06, practice and arrive-and-drive | ||
| Sparco X-Pro | ECE 22-06 | 53 – 63 cm |
| Sparco Club X1 | ECE | 54 – 65 cm |
| OMP Circuit Evo 2 | ECE 22-06 | 53 – 61 cm |
ECE 22-06 helmets are road motorcycle homologated. They are popular for practice, arrive-and-drive and indoor karting, and they cover the widest size range, but most competition series will not accept them. Check your regulations first.
Ladders by brand
All measurements are head circumference in centimetres.
BellNumeric on most kart models. Pick your measured size.▼
| Model | Sizes |
|---|---|
| KC7-CMR | 54, 55, 56, 57, 58, 59 |
| KC7-EV CMR and CMS | 51, 52, 53, 54, 55, 56, 57, 58, 59 |
| Carbon KC7-CMR | 52, 53, 54, 55, 56, 57, 58, 59 |
| RS7-K Carbon | 54, 55, 56, 57, 58, 59, 60, 61 |
| RS7-K | S 57-58, M 58-59, L 60-61, XL 61 to 61+ |
StiloLettered, and the ST6 KRT offers two different L liners.▼
| Model | Sizes |
|---|---|
| ST5 CMR | XS 54, S 55, M 57, L 59 |
| ST5 CMR Carbon | XS 54, S 55-56, M 57, L 59 |
| ST6 CMR Zero and Lite | XXS 53, XS 54, S 55, S 56, M 57, L 59 |
| ST6 KRT | XS 54, S 55, M 57, L 58, L 59, XL 61, XXL 63, XXXL 64 |
| ST5F N KRT | XS 54, S 55, M 57, L 59, XL 61, XXL 63, XXXL 64 |
Stilo state their helmets run slightly smaller than other brands, so if you are on a boundary go up. The ST6 KRT lists an L at 58 cm and an L at 59 cm; those are two liner thicknesses in the same shell.
SparcoSix different ladders. Read the centimetres in the size name.▼
| Model | Sizes |
|---|---|
| Stealth CMR | XS 53-54, S 55-56, M 57-58, L 59 |
| GP KF-4W CMR | XS 54-55, S 56, M 57-58, L 59 |
| Air KF-7W, Sky KF-5W | XS 53-54, S 55-56, M 57-58, ML 59, L 60, XL 61, XXL 62 |
| X-Pro | S 55-56, M 57-58, L 60, XL 61, XXL 62 |
| X-Pro Gulf and Martini | XS 53-54, S 55, M 56-57, L 58-59, XL 60-61, XXL 62-63 |
| Club X1 Carbon | XS 54-55, S 56-57, M 58-59, L 60-61, XL 62-63, XXL 64-65 |
None of these matches Sparco’s car helmet ladder, and several do not match each other. A Sparco kart M can be 56-57, 57-58 or 58-59 cm depending on which model you are looking at.
OMP and AraiBoth use the same ladders as their car helmets.▼
| Model | Sizes |
|---|---|
| OMP GP-R K | XXS 52-53, XS 54-55, S 56-57, M 58-59, L 60-61, XL 62-63 |
| OMP Circuit Evo 2 | XS 53-54, S 55-56, M 57-58, L 59, XL 60, XXL 61 |
| Arai CK-6 | XXS 51-52, XS 53-54, S 55-56, M 57-58, L 59-60 |
| Arai SK-6 | XS 53-54, S 55-56, M 57-58, L 59-60, XL 61-62 |
How it should fit
Snug enough that it is slightly awkward to pull on, with the cheek pads pressing the cheeks up. With the strap done up you should not be able to rotate the helmet forwards off the head. The lining beds in over the first few sessions, so a helmet that feels merely comfortable in the box will be loose by the end of the season.
For a child, check it again at the start of every season rather than assuming last year’s helmet still fits. Heads grow faster than you expect and the fit goes off before the helmet looks any different.
Ladders read from the size options on our own products, which carry the head measurement in the size name. Bell numeric models follow Bell’s published HP, Carbon and Pro chart. Arai and OMP kart ladders match their published car ladders. All checked 2 August 2026.
