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How To Measure Bike Helmet Size

How to Measure Bike Helmet Size

Guest Contribution by Alexandra Betty

Similar to any other sport or extreme activities, safety comes first in cycling. And while there are many protective gear that you can choose to get, wearing a helmet is a must.

However, purchasing and wearing a helmet alone may not be sufficient to safeguard yourself while cycling. How so? Because wearing the wrong equipment can limit its performance. Thus, it’s vital to know how to measure your bike helmet size and to get a fitting helmet.

This article will focus on full-faced bike helmets. These are the most complex ones to choose due to covering all of your head’s circumference. However, feel free to use the tips here to choose a road cycling or commuter helmet, if that is what you prefer.

How to Measure Bike Helmet Size

How to Measure Bike Helmet Size- Finding the Correct Size of A Full-Face Bike Helmet

This video shows how  you could get started with fitting a bike helmet (Credit to Art’s Cyclery):

There are several things to consider if you’re looking for the correct full face mountain bike helmet size for you. Simple as it may sound, the objective here is to fasten the helmet so that your head doesn’t move freely within it.

However, some factors may make it too tight, which is not favorable at all. Full-faced bike helmets should fit low on the brow, with your eyes centered in the eye-opening. It should touch the top of the head all around.

Cheeks must also be in full contact with the helmet cheek pads. But, once again, pressure must not be excessive. Finally, you should be able to fasten the chin strap and shake your head without feeling it move freely.

Here are some tips for you to take into account when measuring your bike helmet size:

  • Head size (circumference): Heads may look alike, but when it comes to size, you’ll realize they are quite different from each other. Place a measuring tape around your head to check your head size. The tape should rest right over your eyebrow line and the most prominent part of the back of your head. Take several measures and keep the largest one in mind.
  • Head shape: Just as with size, head shape also differs among different people. You can easily identify if your head is more a round-shaped one or tends to be more oval by taking a look in the mirror. Look at your cheekbones and how your face-line behavior as it goes down to your chin. Always remember to do this with both eyes centered in the mirror.
  • Hair: Your hair also plays an important role when choosing your bike helmet. Thick or long hair may require a bigger size, for example. Curly hair tends to be more compact as well. Furthermore, if you’re planning to have a ponytail, you should look for a helmet with an outlet on the back.
  • Tools to measure your head: Measuring tapes are the most common and practical tools to measure your head size. However, other tools, such as spreading calipers, can help. If you don’t have any of them, you can use a piece of string and then measure it using a ruler.


What Sizes Do Full-Face Bike Helmet Manufacturers Use?

When it comes to full-face bike helmets, there’s a wide variety for you to choose from. Getting the correct size based on the factors mentioned above is crucial to protect yourself from possible injuries.

Fortunately, manufacturers usually follow universal standards for helmet size. This simplifies the arduous task of choosing the correct protective gear and will help you to get on that bike and start pedaling in no time.

You can use this list to help you out while deciding which is the correct helmet size for you. If you happen to know your cap size already, it might also come in handy.

  • XS bike helmets generally correspond to a 22-inch (56cm) head size. Also, if your cap size is 7, this is the correct one for you.
  • If your head circumference is 22.5 inches (57cm), you should opt for an S-sized helmet.
  • The M size corresponds to a head circumference of about 23 inches (58-59 cm) and a cap size up to 7 ⅜.
  • You should go for an L size if your head circumference is 23.5 inches (60 cm).
  • Finally, the XL helmet size would be correct for a 24-24.5 inch (61-62 cm) head circumference.

How to Measure Bike Helmet Size

What Else Can You Do to Fit Your Helmet Properly?

Even after measuring your head circumference and contemplating its shape or considering your hair thickness and style, your full-face bike helmet may still feel too loose. Fortunately, there are some add-ons you could buy to adjust for a secure fit.

Firstly, you can use foam pads on the sides or top if there is a gap between the helmet’s inside part and your head.

Secondly, most advanced bike helmets have adjustable knobs. Tighten or loosen them to achieve the correct fit. Remember that shaking your head is a great way of checking this out. Your helmet shouldn’t move freely, following your head’s movements.


Knowing exactly what you need to safely perform a sport such as mountain biking or cycling is also part of the preparation plan. In this way, you can feel safe enough to perform any tricks you want or ride through challenging trails.

Of course, you must always pay attention to the road and be aware of the dangers around you. But having the correct gear is a great “safety net” when you hit the track.

Author Bio

Alexandra Betty has been riding bikes since the age of seven, and her enthusiasm for cycling has never dropped. In her family, she is known to have a high level of craze for cycling. She has won many local bike races and participated in several long bike tours across the United States. She strongly believes that bike riding helps people to stay calm, healthy and peaceful. She is also an advocate of using cycling as a means of overcoming depression.