A helmet that doesn’t fit properly isn’t just uncomfortable — it’s dangerous. Too loose and it won’t protect you in a crash. Too tight and it becomes a distraction on the road. The good news is that measuring your head for a motorcycle helmet takes less than two minutes and requires only a flexible tape measure.
What You’ll Need
- A flexible fabric or paper tape measure (not a metal one)
- A mirror, or a friend to help
- A pen and paper to note the measurement
Step 1: Find Your Measuring Point
The correct measuring point is the largest circumference of your head — typically about one inch (2–3 cm) above your eyebrows at the front, and at the widest part of the back of your skull. This is your head’s maximum circumference, which is what helmet manufacturers size to.
Step 2: Wrap the Tape Measure
Hold the tape measure at your forehead (about 1 inch above your eyebrows) and wrap it horizontally all the way around your head, keeping it level. Don’t pull it tight — it should sit snugly against your skin without compressing. Keep it parallel to the floor the whole way around.
Step 3: Read the Measurement
Note the number where the tape meets itself. Measure in centimetres — helmet sizing is almost universally based on centimetres, even in the US. If your tape only shows inches, multiply by 2.54 to convert.
Measure Twice
Do it at least twice to make sure you get a consistent number. A 1cm difference between readings usually means the tape shifted — take the larger of the two readings if in doubt.
How to Use Your Measurement
Once you have your head circumference in centimetres, match it to the brand’s size chart. Sizing varies between manufacturers — a Medium from Shoei may fit differently than a Medium from Bell. Always use the specific brand’s chart, not a generic one.
| Head Circumference (cm) | Typical Size |
|---|---|
| 53–54 cm | XS |
| 55–56 cm | S |
| 57–58 cm | M |
| 59–60 cm | L |
| 61–62 cm | XL |
| 63–64 cm | XXL |
Note: This is a general guide. Always verify with the specific brand’s sizing chart before buying.
Head Shape Matters Too
Circumference is only part of the equation. Helmets are also shaped differently — most fall into three categories: round oval, intermediate oval, and long oval. If a helmet feels like it’s squeezing your temples but loose at the front and back (or vice versa), the shape may not match yours regardless of the size. This is why trying before you buy is always the best approach when possible.
What a Proper Fit Feels Like
When you put on a correctly sized helmet, it should feel snug all the way around with no pressure points. It should not move when you shake your head side to side, and you should not be able to fit more than one finger between your forehead and the helmet’s liner. Some mild initial tightness is normal — liners compress and mold to your head shape over the first few rides.
When to Size Up
If you’re on the borderline between two sizes, try the smaller one first. Most helmets will break in to feel slightly looser after 15–20 hours of use as the liner conforms to your head. Starting too loose means it will only get worse over time — and a loose helmet can come off in a crash.
Getting your helmet size right is the single most important thing you can do before buying. A great helmet that doesn’t fit is worse than a budget helmet that does.