Is it time to replace your race suit? Let’s get you track-ready. What Size Motorsport Helmet Do I Need? Our Measuring And Fitting Guide
Every helmet listing on the site asks for a size, and half the messages we get about helmets are some version of the same worry: what if I order the wrong one. Fair worry. A helmet that is wrong by one size is not a small annoyance like a loose glove, it is a helmet that moves when you do not want it to, or one that gives you a headache by the third lap.
The fix is ten minutes with a tape measure and knowing how the sizing actually works, which is what this page covers. Measure first, then read the chart on the listing you are buying from, then check the fit properly when it arrives. Do those three things and the size question mostly answers itself.
Measure before you shop
Helmet sizes are head circumferences in centimetres. The letters are just labels stuck on those numbers, so the measurement is the only part that transfers between brands.
Take a flexible tape measure, the sewing kind, and run it around the fullest part of your head: about two centimetres above the eyebrows, above the ears, and around the widest point at the back. Keep it level and snug without pulling it tight. Do it three times and keep the biggest number, because the tape drifts low at the back more often than it drifts high.
No tape? A length of string and a ruler does the same job. What does not do the job is guessing off your hat size or ordering the middle size because it is probably fine. Heads are longer or rounder from person to person at the same circumference, which is also why the number gets you to the right size to try, not to a guaranteed fit.
The letters mean different things
Here is where people get caught. A medium is not a medium everywhere. These are the size charts from four helmets we stock, exactly as the manufacturers publish them.
| Size | OMP GP-R | Bell R7 Sport | Sparco Flux RJ-i | Stilo Venti4 |
|---|---|---|---|---|
| XS | 54-55 cm | – | 53-54 cm | 54 cm |
| S | 56-57 cm | 57-58 cm | 55-56 cm | 55 cm |
| M | 58-59 cm | 58-59 cm | 57-58 cm | 57-58 cm |
| L | 60-61 cm | 60-61 cm | 60 cm | 59 cm |
| XL | 62-63 cm | 61-62 cm | 61 cm | 61 cm |
| XXL | – | – | 62 cm | 63 cm |
Read it across the 60 cm line: that is a Large in a Bell R7 and an OMP GP-R, a Large in the Sparco Flux, and closer to an XL in a Stilo Venti4. Same head, three different letters. Sparco also cut an ML at 59 cm that most other brands skip, OMP go down to an XXS at 52 cm, and Stilo run up to an XXXL at 64 cm.
The rule that follows: never order by the letter you wore in another brand. Order by your centimetres against the chart on the listing in front of you. Every helmet on the site carries its own chart in the size dropdown for exactly this reason.
How a helmet should actually fit
When it arrives, put it on and leave it on for ten minutes. Not thirty seconds in front of the hall mirror. Pressure points announce themselves slowly, and ten minutes tells you what three hours in the car will feel like.
You are looking for firm, even contact all the way round. On a full face the cheek pads should press enough that your face moves with the helmet, and squeezing your speech slightly is normal on a fresh liner. What you should not feel is a hot spot, usually the forehead or the crown, and you should not see a gap above the eyebrows.
Then the two checks that catch a size too big. Hold your head still and try to rotate the helmet side to side and up and down: your scalp and cheeks should move with it, the helmet should not sweep across your skin. Then with the strap done up, grab the rear lip and try to roll it forward off your head. If it comes off, it is too big, whatever the chart said.
The liner will bed in a little over the first few sessions, so between two sizes take the snug one. Loose never gets better. And if you wear a balaclava in the car, wear it for the fitting, it is thin but it is not nothing.
Helmets we would size you into
Three of the helmets we fit most, all carrying the current FIA 8859-2024 approval. The same measuring routine applies to every helmet on the site, these are just where I would start a conversation.
Stilo Venti4 Trophy, for the rally crews
The Venti4 Trophy Plus is the rally spec with the intercom provision the stage crews want, and the Trophy Jet is the open face version of the same shell. Stilo cut more sizes than anyone else here, eight of them from 54 to 64 cm, which is a genuine advantage if your head sits between another brand’s sizes. It also holds Snell SA2025 alongside the FIA approval.
- FIA 8859-2024, and Snell SA2025 on the Trophy Plus
- Eight sizes from 54 to 64 cm, the most on this page
- Full face Plus or open face Jet from the same family
- Intercom-ready for stage rally use
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From £315.00 Select options This product has multiple variants. The options may be chosen on the product page
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From £519.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
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From £566.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
Bell R7 Sport and GP3 Sport, for the circuit drivers
The R7 Sport is Bell’s current circuit shape and the one I would put most track drivers in first. Bell’s chart is the classic S to XL spread, and their M covers 58 to 59 cm. The GP3 Sport sits alongside it and runs M to XL, so if you measure under 58 cm the R7 is the Bell to look at.
- FIA 8859-2024 approved
- Bell M covers 58-59 cm, L covers 60-61 cm
- R7 Sport carries the wider size range of the two
- HANS post provision as standard
Sparco Flux RJ-i, the all-rounder
The Flux RJ-i covers the widest brief, track days, sprints and hillclimbs, and Sparco cut it in seven sizes including that 59 cm ML most brands skip. If your tape says 59, this is the easiest right answer on the page.
- FIA 8859-2024 approved
- Seven sizes from XS 53-54 cm to XXL 62 cm
- The only ML at 59 cm on this page
- Also sold as a package with a HANS device, below
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From £415.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
Sizing when a HANS is involved
If you run a HANS or hybrid device, get the helmet size right first and the device second. The helmet size does not change because a HANS is involved: the device connects through posts on the shell and the fit inside the helmet is exactly the same conversation as above. What changes is that a helmet that rotates because it is too big is even less acceptable, because the tethers rely on the helmet staying put.
Every current FIA approved helmet we sell has HANS post provision, and the packages below pair the Sparco helmets with a Simpson Hybrid Sport or a Schroth XLT in one order. Size the helmet with your tape, then the device goes by collar size and harness angle, which is its own guide for another day. Ask us and we will spec the pair in one go.
Karting and junior sizes
Karting helmets follow the same measuring routine, the sizes just run smaller, and junior helmets are approved to the CMR standard, an approval written specifically for children. Measure a growing driver’s head the same way, buy the size that fits now, and accept that you will be back. A junior lid bought two sizes big to grow into fails the rotation check on day one, which defeats the point of it. The karting range is here.
Common questions
I measure exactly between two sizes. Which one?
Do I measure with or without a balaclava?
Is a medium the same in every brand?
How tight is too tight?
My glasses have to fit under it. Anything different?
Can I try helmets on before buying?
The short version
Measure the fullest part of your head three times and keep the biggest number. Buy against the chart on the listing, not the letter from your last helmet. When it arrives, wear it for ten minutes, then do the rotation check and the roll-off check. Between sizes, take the snug one.
Get those right and the size question is done, and you can spend your energy on the question that is actually interesting, which is which helmet.
Final thoughts: the tape does not lie
Most sizing problems we see started with a guess. The full range is under motorsport helmets, with the open face lids in their own category.
Send us a message with your measurement and what you drive, or ring 0115 9893488 and book a fitting. Either way you end up in a helmet that fits, which is the whole job.