Motorcycle crash helmets fitting guide

When you buy a new helmet, it’s mega important you make sure it fits correctly. Not only do badly-fitting motorcycle crash helmets make you grumpy and give you unseemly red marks across your forehead when you take them off, they’re also much less effective in an accident.

According to SHARP (and pretty well every motorcycle safety organisation on the planet), ensuring your helmet fits right is the number one factor in making sure any helmet will give the best protection it can in an accident. I know we go on about buying a helmet that’s safe and highly rated by SHARP, but that’s secondary to ensuring the helmet you’re wearing fits well. And that goes for any helmet.

So how do you go about making sure a helmet fits well in the first place – and what does a well-fitting helmet feel like? Here goes…

1. Measuring

You need to measure your head size before buying a helmet. Get a tape measure (not the DIY type, the tailor type!) and run it round your head – above the ears, across the forehead and around the back of your head, over the bumpy bit of your head like in the picture above. That’ll give you the reading you need to match it to the correct helmet size.

Occasionally a helmet will size a little larger or smaller then it should. When this is the case, we’ll mention in our reviews so you can order the correct size (though all our recommended retailers will allow you to exchange helmets if you order the wrong size).

2. What’s your Head Shape?

Most helmets these days tend to be a medium oval shape – that’s the shape most of our heads tend to be in the West so helmet manufactuers try and make their helmets to suit. However, some helmets are made to accommodate folks with longer, narrower heads as well as rounder head shapes (though there’s very VERY few of these).

We mention in most of our reviews which head shape each helmet works for but if you’re unsure which head shape you’ve got, it’s probably worth trying a few helmets out first to work out which brands suit your particular head shape.

3. The Squeeze Test

Helmets have polystyrene padding on the inside of the shell to absorb any impact and thereby protecting your head. This should be relatively snug fitting because if there’s a gap between it an your skull, it’s not going to stop the outside shell of the helmet accelerating towards your skull and causing an impact. So, when you try a new helmet on, it needs to be snug fitting. Not so tight that when you put it on it shoves your ears down towards your neck and squeezes the blood from your skull – but moderately tight. You should be able to feel the polystyrene (EPS) padding touching all of your head without and pressure points. Keep the helmet on your head for a few minutes to make sure it’s comfortable.

4. The Twist Test

If you watched the video on John Reynold’s post accident Arai, he talks about helmets not twisting around on the head. That’s important. Accidents tend to try and twist helmets around and if it’s too loose, that’s exactly what it’ll do. So with your head in a new helmet and the strap fastened, try turning the helmet. It should stay (more or less) put.

5. The Rock Test

Again with the helmet fitted and the strap tightened, try pushing the helmet up from the rear or up from the front. If the helmet moves too much either way, then it might not be quite right for you. Obviously, it’ll move a little but if it moves so much it covers your eyes or exposes your chin, then you should probably look for a different helmet.

6. The Loosening

The lining of a new helmet will loosen over time as it slightly compresses through use. So when you get a new helmet, again, it should be tight enough to stop it moving about and being tight, but not too tight; knowing that it’ll loosen slightly over the first month or two.

7. Lining

If you’re interested in cleanliness, try making sure the linings can be removed – covering the crown and cheeks. Most helmets these days have removable linings that you can clean by sticking in the washing machine or washing by hand. Click to see all helmets we’ve covered with removable and washable linings.

8. Fasteners

Race helmets have double-D ring fasteners which are pretty much a standard fastening required by the various racing governing bodies. However they’re not necessarily the best and there are really simple and easier to operate alternatives available – such as micrometric-style fasteners which many riders like and are the most common type on non-race helmets. So have a look at the different fasteners before you buy to see which you get on with best.

Whichever fastener you choose, they need to be fastened and adjusted reasonably tightly to keep the helmet on the head during an accident. The good thing about double-D ring fasteners is that you have to tighten the strap every time you use it – though you still need to be diligent enough to make sure you tighten it up correctly.

Micrometric buckles are easy to use but they need to be readjusted from time to time. They use a ratchet strip which offers adjustment within a set range each time you fasten it. But over time, the strap may stretch a little so you’ll have to readjust the strap itself and not just rely on the ratchet.

9. Buying from a Website

Obviously, there’s a certain amount of risk buying a helmet over a website because it’s important to try a helmet on to make sure you get the right fit. When you do buy a helmet online, you need to make sure you can return it and get a replacement without any problems. At BillysCrashHelmets, we’ll only suggest suppliers who’ll allow this without giving you grief and in some cases they pay for the return (except on Amazon where there’s a ton of different sellers – so please be careful).

And don’t forget you’re always protected with the UK Consumer Contracts Regulations giving you a guaranteed right to return for a refund within 14 days of receiving your goods (other European countries have their own version).

If you’ve got any tips which worked for you, please let us know – we’d love to hear!


  1. Hi. Can you please clarify which direction you are talking about when you talk about helmet shape? I couldn’t see it anywhere. I’d always thought this was the front to back we’re talking about. I.e. a longer oval would be long front to back compared to the distance between the sides of the head. But I thought I read something a little while back (which I can’t find quickly), that it was actually talking about the up down dimension. So that a long oval is someone who has a taller, narrower face.

    I have a head which is long front to back compared to side to side. My Schuberth C3 gives me problems on my forehead. My missus had similar with a Caberg modular. On advice of a dealer, she switched to a non-modular as they said that most modulars are not good for longer (front to back) heads. She’s now very comfortable.

    I’m looking for a replacement (ideally a modular). I will try instore of course but I tried the Schuberth. The issue only shows itself after about an hour, but then quickly becomes unbearable.

    • Yeah long oval is longer front to back than medium oval. Up down dimiensions are important especially if you’re wearing a race helmet so you have adequate view ahead when you’re tucked in. Check our long oval helmets page to find longer oval helmets – a great place to start your search!

  2. Hello, Just wondering if you cover helmet shell sizes, maybe with Agv, shark, Bell in particular. Im currently in the market for a helmet, and at the moment most shops will be closed, so its impossible to judge shell sizes that aren’t on my. mobile screen. My head measurement is 57.5cm Intermediate Oval so it looks like im a medium, but I need to find helmet with a shell size that doesn’t make me look like Paul the alien. Maybe you could (or maybe already have) covered various shell sizes and most importantly comparisons with different body sizes and other helmet shell/Head measurement sizes? Just a thought and thanks for your time.

    Kind regards.

    • Hi Mike. Not exactly. We’ve got pages covering the different internal fits of course – like medium oval or long oval for example. But where a helmet’s been judged to be particularly compact or really big, we’d mention it in the body of the review – usually in the Safety or Comfort sections. It’s often an issue when a helmet’s made in very few shell sizes so we’d mention that in the Safety section too – where the info’s available. So there’s no easy way to pick it out unfortunately but if you see a helmet you like, if there’s an issue either way then we would likely mention it. If it’s not really been an issue for owners, then we wouldn’t. Hope that helps – happy helmet hunting 🙂


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