How to Measure Bike Helmet Size | A 5-Step Guide

Wearing a helmet is a crucial safety requirement when riding a bike. However, if you don’t get the right size, the helmet can’t keep you safe and comfortable. So, it’s advisable to know how to measure your bike helmet size before you get one for yourself.

A properly sized model with quality mountain bike helmet lights will give you the best protection from injury and maximum comfort. In this article, I’ll share with you the steps to determine the right bike helmet size.

How to Choose the Bike Helmet That Will Perfectly Fit You

Like I mentioned earlier, a helmet is an essential safety accessory for anyone riding a bike. It doesn’t matter whether you’re just riding your bike for fun, or you’re an athlete, you need to get the right size for your bike helmet. Otherwise, it can’t keep you safe and comfortable, especially if you’re mountain biking.

I know that there are several innovative and beautiful helmet designs out there. But don’t ignore the comfort and safety that any helmet will give you. And you can’t get these two features if the helmet doesn’t fit your head perfectly.

So, in the next few sentences, I will be sharing with you some helpful tips to choose the right size of your bike helmet.

1. Measure Your Head

It’s easy to measure the size of your head. All you need to do is to get a soft tape or piece of string and use it to carry out the measurement.

The first thing you should do is to wrap the soft tape measure or string around your head little above your eyebrows and take note of the measurement.

If you prefer using a string, hold it straight and flat next to the tape measure after measurement. The reason for this is to ascertain the accuracy of the measurement.

2. Put the Helmet On

You may make a mistake while measuring your head. So, after choosing a helmet that matches your head measurement, it’s recommended to try it on before leaving.

The first thing you should do is to check whether the helmet sits level on your head and you can still see the bicycle mirror that you have mounted on the handlebar. And the front should be about an inch above your eyebrow; this is the only way it can protect your forehead.

Every helmet has a retention system which you can use to adjust its fit on your head. Again, ensure that there’s no space between the helmet and your head. Otherwise, it will not feel snug when you use it.

Don’t forget to check out for pressure points, once you observe any; the helmet is too small. Always pay more attention to safety and comfort than design.

3. Tighten the Chin Strap

It would help if you buckled up after wearing your helmet. It’s easy to do this. Simply connect and tighten the chin strap. The essence of tightening the chin strap is to make the helmet feel more comfortable beneath your chin.

At this point, you will feel the helmet pressing against your head. This is an indication that the helmet is a perfect size.

4. Shake Your Head

A shake test is another great way to choose the right size of a bike helmet. It involves shaking your head back and front. If it shifts noticeably, use the retention system to adjust it.

Usually, if the helmet is the right size for your head, it shouldn’t move more than one inch in any direction and neither should your bike helmet mirror if installed correctly.

5. Enjoy Your Ride

Let me remind you of something – your helmet shake test is crucial. Try to give it a quick shake test before going out for any ride. It’s the best way to keep yourself safe while cruising with your bike.

How to Choose the Proper Bike Helmet Size for Kids

Bike helmets aren’t meant for adults alone; kids also need it. If you are riding a bike with your kid, he/she needs to wear a helmet to keep him safe.

While the same rules of choosing the right helmet size for adults apply to kids, it’s sometimes challenging to know if a particular helmet fits your child’s head perfectly. This is because most kids can’t precisely explain how snug their helmet feels.

At all times, pay attention to your child’s comfort while using a helmet. And always remember that any helmet that’s too large is unsafe for your child.

Bike Helmet Fit Systems

If you understand how to measure bike helmet size, you will probably know how bike helmet fit systems work. Most modern bike helmets have ratcheting fit systems or removable pads; they both help to adjust the fit of the helmet.

1. Ratcheting Fit System

The ratcheting bike helmet fit system provides a close fit, and it’s less likely to break down due to sweat. It either has a dial, crank, or ring at the back which enables you to customize the fit. Remember, the fitter a helmet on your head, the safer and more comfortable you will be when riding your bike.

2. Removable Pads

Some helmets feature removable pads which mostly come with a set of pads. With these pads, you can fully customize the helmet to fit you perfectly.


Learning how to measure bike helmet size is easier than you think. All you have to do is to follow the steps explained in this article. Furthermore, when getting a bike helmet, you must consider safety, fit, and comfort.

When a helmet fits your head perfectly, you’re less likely to sustain injury when you have an accident with your bike. Again, try to carry out a shake test whenever you want to ride your bike. Also, inculcate this habit on your kid if you always go riding with them.

It doesn’t take much time to wear your helmet and observe little safety tips. You should spend time keeping your helmet safe on your head. After all, safety is everybody’s business.

Shailen Vandeyar

A proud Indian origin Kiwi who loves to plant trees and play with my pet bunny when not out cycling through the best routes, reviewing the latest gear, and sharing tips on everything biking.

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