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How to Measure for a Bike Helmet? – Measuring Bike Helmet Properly

Written by Gary Johnson / Fact checked by Henry Speciale

how to measure for a bike helmet

Wearing a bicycle helmet is part of bike safety. But getting an ill-fitting one can still lead to road accidents and injury. Helmets can come in small, medium, large, and extra large and are usually measured in centimeters.

With all these sizes, you can be confused about the best helmet suitable for your needs. Thus, we created this post about how to measure for a bike helmet to provide you the right information on helmet sizing. Here is a summary of the steps you will need to take:

  • Measure up
  • Pick out some helmets
  • Test them out
  • Make adjustments
  • Do the shake test


Sizing Parameters and Helmet Guide


Size does matter when it comes to bike helmets. Using the wrong bike helmet measurements can compromise safety, and waste your money. It is crucial to get the right sizing before purchasing a bicycle helmet.

Smaller helmets can build up more sweat when you are on the road because limited air will be able to circulate. A smaller size helmet will also leave marks on your head, and can make you uncomfortable.

On the other hand, a bigger helmet can easily come off, which poses a greater risk for road accidents. It could also block your view when you are on the road, making it hard for you to bike properly. A big helmet cannot offer the right protection during a crash or collision. The helmet can easily be removed from your head, leaving you no protection.

Thus, it is crucial to get a helmet with the correct fitting. You will know the right size if it is an inch or more above your eyebrows. You can easily obtain this by using a measuring tape and following the steps below:

  • Measure up
  • Pick out some helmets
  • Test them out
  • Make adjustments
  • Do the shake test

Materials needed:

For this tutorial, you only need a measuring device, specifically a fabric tape measure. It is flexible and allows you to fit the fabric around your head. This tool gives you more precise measurements.

Measuring Bike Helmet Properly


1. Measure head size for bike helmet

It is important to use the right tool in measuring for a bike helmet. Fabric tape measure is preferable when getting your head size and when you measure for a bicycle helmet. You can wrap it around the head just an inch above the eyebrows and your ears. It is crucial that the tape measure goes around the largest area of the back of your head. In this way, you can obtain the right circumference of your head in centimeters.

2. Pick out some helmets

After you measure head for bike helmet, try out some helmets. Choose several products that meet your head size. There are different bike helmet sizes, and you can easily spot the right one that corresponds to the measurement of your head.

To get the correct size and fitting to your head, it is better to visit a helmet store, than ordering online. You can use this table when picking a helmet product:

Helmet Sizing Measurement (in centimeters)
XS 53 to 54
S 55 to 56
M 57 to 58
L 59 to 60
XL 61 to 62
2XL 63 to 64
3XL 65 to 66

3. Test them out

Once you have picked out the helmets within your size range, you can test them out to get the best fitting. Make sure that you try out several helmets, and remember that a helmet must cover your entire forehead to protect the front lobe of your brain. Also, observe the comfort level you experience while putting the helmet on.

4. Make adjustments

Make adjustments with your helmet so it can perfectly fit on your head. Helmets come in various features, which include an adjustment system. The more expensive the product is, the more adjustment options there are. With this, the fitting of the helmet on your head is more accurate and precise.

Ensure that your helmet comes with adjustable straps so it remains firm when riding. When wearing it on your head, observe the tension provided. It must be evenly spread out to deliver optimal comfort.

When making adjustments, you should connect the chin strap so it snugs comfortably beneath your chin. Ensure that you are able to fit one finger between the helmet strap and your chin. When you open your mouth wide, you should feel the helmet pressing against the top of your head, too.

Remember, do not buy a helmet that is too tight. It can rub on your head and leave marks on your skin. It also offers poor ventilation, making the product an undesirable fit.

5. Do the shake test

Once you put the helmet straps on, the last step is doing a shake test. You should shake your head around, from side to side, and in every direction. Make sure that the product does not move an inch in any direction. Check whether the straps are loose, make sure they do not compromise comfort.


Bike helmets are meant to protect you from potential accidents. But without the right fitting, it can still compromise your safety. Good thing, we have this simple guide on how to measure for a bike helmet. We keep the steps simple and concise. May you find them helpful when you buy your next bicycle helmet.


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