How To Measure Head For Bike Helmet – Step by Step Guide

A bike helmet’s proper fitting is the key factor to ensure head safety and comfort. So, to get the right size helmet is far more important than its style and look. Branded helmets come with different size names like X-small, small, medium, large, X-large, universal adult size, toddler size, and youth size, etc. But don’t confuse with that series of sizes. If you know your head shape and circumference then helmet size selection becomes very easy. In this article, the following simple steps will guide you on how to measure head for bike helmet.

Before buying any Bluetooth bike helmet online you must need to know the size and shape of your head. Otherwise, you have to face a bad experience of wrong size helmet delivery.


How to measure head for bike helmet

How to measure head for bike helmet

To find the most suitable size of the Mtb helmet you need to measure your head circumference first. Take a flexible measuring tape and wrap it around your head. During measurement, keep the following points into consideration.

  • Keep measuring tape roughly 1 inch above your ears and eyebrows.
  • Measuring tape should pass over the bump at the back of your head. (lower back part of the skull).
  • Try to measure the largest or widest part of your head.
  • Take more than one measurement and choose the largest one.
  • If you are doubtful take someone’s assistance.
  • If you have long hair then remove any hairstyle that can affect the measurement.
  • You can also use a piece of string for measurement and then lay it next to the tape.
  • Try to use a centimeter-scale to mark the total distance around your head.

Now match your measurement with the given range size by manufacturing companies.

Bike helmet size chart

Size nameFit range in cmFit range in inches
Toddler size46-5018.11-19.68
Extra-small /x-small47-5118.5-20
Small/ medium51-5820-22.83
Medium /large55-6121.65-24
Extra-large/ x-large61-6524-25.6
Universal adult size54-6121.25-24
Universal women size50-5719.68-22.4

Important note!

If your head size is on the edge of two sizes then it is better to choose an upper size. Because mostly helmets come with additional pads to maintain a snug fit. The additional pads are only beneficial if you choose an upper size.

4 easy steps to get a perfect fit helmet

Step 1: Consider your head shape before purchasing

Helmet size numbers do not tell anything about helmet shape. Most helmet manufacturing companies are designing shells according to the most common head shape of people. But every person’s head shape is not the same. Sometimes, two people of the same head circumference do not find the same size helmet equally comfortable.

This is the only reason for all complaints related to the helmet size. So, head shape consideration is also very important. Now, some companies also include the length to width ratio of helmet interior which can give a rough idea of helmet shape.

Types of head shapes


  • Round Oval shape (Less common):  When you see the top view of this type of head then you realize that forehead–to–back and ear-to-ear distance is the same. In other words, the length-to-width ratio of this type of head is 1.
  • Intermediate Oval shape (Most common):  This type of head shape is slightly longer from forehead-to-back than from ear-to-ear. Its Length-to-width ratio is approximately equal to 1.3.
  • Long oval shape (Less common):  In this type, forehead-to-back distance is longer than then ear-to-ear. Its length to width ratio is roundabout 1.5

Types of head shapes


How to find head shape for bike helmet

It is important to take a rough idea about your head shape before buying a helmet. You can use your mobile front camera to capture the top view of your head. You can also take someone’s assistance to take a photo of your crown

Important note!

If your head shape is in the category of less common then choose a helmet with an upper size of your head. Because a relatively big size helmet can adopt any head shape by using thickness pads to maintain snug fitting.

Step 2: What is the correct position of a helmet on your head?

correct position of a helmet on your head

First of all, the helmet should sit on your head so that there is no pressure point and undue movement. Now, it’s time to consider the helmet’s correct position on your head.

If your helmet is tilted in a forward position then it can obstruct the front view during the ride. And backward tilted helmet cannot protect your face or forehead in event of a crash.

So, the helmet should sit about two finger-widths distance above your eyebrows. It has been proved experimentally that the helmet’s correct position gives more coverage to rider’s head in the event of a crash.

Step 3: How to adjust dial knob for a snug fit

How to adjust dial knob for a snug fit

After correct position sitting of the helmet on your head, you need to tune fit tension by using the back dial knob. Turn the knob for tightening but not to an uncomfortable level.

Before buckling the chin strap, shake your head to test the helmet snug fitting. During the test make sure that the helmet must stay firmly in place.

Step 4: How to adjust chin strap according to face length

How to adjust chin strap according to face length

The helmet Tri-glide chin strap should sit flat around your face. Moreover, helmet straps should come together to form a V at the base of your ears.

Fasten the buckle correctly after making sure the proper sitting of chinstrap around your face. To keep the chin strap from loosening it must pass through the keeper. Chinstrap should rest comfortably under your chin without putting any pressure on your skin and throat.

Adjust the length of the chinstrap in such a way that you can buckle it easily. But after buckling, it becomes tight enough that you can insert only 1 finger between the chin and strap.

Frequently Asked Questions

Why does a helmet need to fit properly?

A study has shown that a helmet can provide certified protection only if it is properly fit on the rider’s head. So, it is not enough to just wear a helmet. A helmet can only provide the highest level of protection when it covers the rider’s head properly. According to a survey, 35% of the total injured cyclists who were wearing a helmet get severe injuries due to improper fitting of the helmet.

How can I know bike helmet fit properly on my head?

Keep the following point into consideration to check the proper fitting of a helmet

  • There should be only two finger width distance between the helmet and eyebrows.
  • You are able to see the front rim of the helmet visor.
  • Your skin should move with the helmet when you shake the helmet on your head.
  • Helmet must sit properly on your head; there should be no pressure point.
  • Chinstrap should form V at the base of your ears.
  • Chinstrap should rest comfortably with your face skin.
  • There should be no pinch point between the dial knob and the skin.
When should I replace my helmet?

Generally, you should consider replacing your helmet after 3-5 years if the helmet has not experienced any significant impact. This is because helmet material degrades due to sunlight, sweat, and other environmental effects. However, CPSC recommended time for replacement is 5-10 years.

If you notice any crack or physical damage then immediately change your helmet. Because it can no longer protect you from any crash. Chinstrap and fit system is most critical to consider for helmet replacement.

How to prepare for head measurement?

If you are wearing braids or a ponytail then remove it before measuring your head circumference. Everything like clips and barrette that can interfere with your head measurement must be removed.

How do you measure your head for a helmet without tape?

If you don’t have flexible tape then you can use a non-stretchable piece of string. Simply wrap the string around your head by keeping it roughly 1 inch above the ears and eyebrows. The string should pass over the bump at the back of your head. After marking lay the string on a flat surface and use a ruler to measure it.


Learning how to measure head for bike helmet is very easy. After following this guidance you can get a perfect fit helmet easily. This article is very beneficial to understand the relation of head safety with helmet perfect fitting. These steps do not take much time to understand. However, you can find a permanent solution to your helmet size after following these steps. We did our best to guide you about how to measure head for bike helmet. Please Give us feedback in the comments!

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