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How To Measure Your Bike Helmet Size With A Tape Measure

Woman wearing a bike helmet

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This guide on how to measure your head and fit a helmet will teach you the basics of how to use a tape measure or measuring tape.

You might be wondering why you would need to know this, but if you’re buying a bike helmet, it’s essential that you know your size! If your head is too small for the helmet but the chin strap is too loose, your head could slip out of the strap. A bike helmet should fit snugly, so be sure to use a tape measure or measuring tape.

The guide is designed with three different types of helmets in mind: children’s helmets, adult helmets and senior helmets. It starts with how to use a tape measure or measuring tape for children’s helmets and then moves onto how to use these tools for adults.

How To Measure Your Helmet Size With A Tape Measure

The first step to measuring your new bike helmet size is to measure the circumference of your head. To do this, you will need a tape measure. Once you have a measurement, you can then use it as a guide for finding the right size helmet that fits comfortably on your head.

Head size: A good way to find out what the circumference of your head is is by measuring around the widest part of your skull with a tape measure and then multiplying it by three inches.

Helmet Size: With these measurements in hand, you can now start looking for a helmet that fits well on your head and where it’s comfortable for you to wear.

You can also use a piece of twine to measure around your head, mark the location on the string, and then measuring that length on the string with a tape measure.

Once you know your helmet size, you can start looking around for your new bike helmet.  You can normally get a best-in-class bike helmet for under $100 that has the best safety features available.

What Is The Best Way Of Measuring Your Head Size?

If you have been looking for ways to measure your head size, a bike head sizing guide is a great option.

This bike sizing guide helps you find the right size bike for your head. However, if you have a smaller or larger head, then it can be difficult to find the perfect fit. If that’s the case, then it might be best to try a few different sizes and see which one fits you best.

For those with average-sized heads, this guide can help you find the best fit in less than five minutes! Even if you bought your helmet within the past 2 years, it is still recommended to measure your head again.

There are three different types of bike helmets - adult youth and children sizes

How To Measure Your Kids’ Bike Helmet Size

The size of the helmet varies with the age of the child. In order to find out what size your child’s helmet is, you can measure it with a measuring tape.

First, put on the headgear and measure the circumference around your child’s head. You will need to do this twice or three times to find out if your measurements are consistent.

Measure your child’s head from right above their eyebrows to one inch below their ears and from left side of their forehead to one inch below their chin.

That is the size measurement you are looking for.

How To Measure Your Adult’s Bike Helmet Size

The size range for a bike helmet is from XS to XXXL. But it does not make sense to buy a big helmet for a small person. In order for the helmet to fit properly, you should measure the head measurement in centimeters or inches and add 17cm or 7in.

The most important thing to remember when buying a bike helmet is that it should fit your head snugly without moving around too much. If the chin strap isn’t buckled, then tighten it so that it’s snug against your chin and shoulder area. The straps should be a little bit loose on the top of your head and tight at the back of your head.

When measuring an adult’s bike helmet size, you must do this with both ears facing forward to get a true measurement.

How To Measure Your Senior’s Bike Helmet Size

We all know that bike helmets are important. But it’s not always easy to make sure your senior citizen is wearing the right size bike helmet for them.

To make sure you get the right fit, measure your senior’s head by wrapping a soft measuring tape around their head. You can also use a piece of string or twine to find the circumference of their head at ear level.

There are three different types of bike helmets – adult, youth, and children sizes. These three different size camps will need different measurements for their own particular needs.

Common mistakes to avoid when measuring for a bike helmet

Measuring for a bike helmet is a straightforward process, but there are some common mistakes you should avoid to ensure an accurate measurement. One of the most significant mistakes people make is measuring in the wrong place.

Make sure to measure the circumference of your head just above your eyebrows and ears for the most accurate measurement. Another common mistake is pulling the measuring tape too tight or too loose. Remember to keep the tape snug but not too tight, as this can lead to an ill-fitting helmet.

Additionally, don’t assume that one size fits all. Every manufacturer’s sizing may differ slightly, so make sure to refer to the manufacturer’s size chart when selecting a helmet. Finally, don’t forget to try on a helmet before purchasing if possible. Trying on a helmet can help you determine if it fits comfortably and securely.

Use these tips to avoid common mistakes when measuring for a bike helmet and ensure a properly fitting helmet.

General Adult Bike Helmet Sizing

Small – 20 to 22” or 51 to 56cm

Medium – 22 to 23.5” or 56 to 60cm

Large – 23.5 to 25″ or 60 to 63.5cm

Once You Know Your Bike Helmet Size It’s Time To Shop

Once you know the right sized bike helmet, it’s time to go check out all of the new bike helmets.  There are some great helmets out there with great safety features like MIPS and the like that have really advanced safety features.  I have lots of articles around bike helmets on the site here, but one in particular will help you learn about the different bike helmets to help point you in the direction you need.

About the Author

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Tony K

Senior Technical Writer,

Tony K is a technical editor at He has a focus on downhill bike riding but still loves xc bikes too.

With more than ten years of mountain biking experience and more than 5 years testing mountain bikes, Tony has ridden and tested hundreds of different bikes and products, everything from XC to enduro bikes. Tony regularly competes in mountain bike races while seeing how long those compontents can hold up which gives me a lot of insight.

When he isn't shredding down a mountain or camping out, he is writing reviews for Mountain Bike Experience.

Rides: Surly Lowside, Canyon Exceed