How to Fit a Child’s Bike Helmet

By Charlotte Murray

A helmet is an important piece of equipment when heading out on your bike and the same applies to children, of course. It’s crucial to their safety on two wheels as they’ll likely be prone to falls early on in their bike-riding journey. Though, of course, they should continue to wear it for as long as they’re cycling.

Another important factor to remember is that a helmet won’t do its job properly if it doesn’t fit right or if it isn’t positioned correctly. Follow our simple steps to get the right fit for your child’s bike helmet.

To ensure a good fit, you’ll have to measure the child’s head. Helmets are not like children’s clothes that you might buy a little big for them to grow into. Instead, the helmet should fit well every time they put it on their head.

A girl on a bicycle
A helmet is crucial for your kid’s safety on two wheels. © Profimedia

What you’ll need:

  • The child
  • A tape measure (or alternatively: a piece of string, a pen/pencil and a ruler)


1. Wrap the tape measure or string around the child’s head, just above their eyebrows – approximately 1-2 adult finger widths – and ears.

2. If using a piece of string: wrap the string around their head, mark where the string meets the other side and measure this against a ruler.

3. Use the measurement to inform your helmet purchase. Check the product description for the size range of the particular helmet, e.g., 52 to 57 cm.

4. Repeat the process a couple of times to ensure you have an accurate measurement.

5. Put the helmet on the child’s head so that it sits flat. It should be just above their eyebrows but covering their forehead for adequate protection and not blocking their view.

6. Universal-fitting helmets will have a dial at the back to adjust the tightness. This should be done before fastening the chin strap. Alternatively, if there is no tightening dial, the helmet may have various sized pads that can be changed inside. The helmet should be tight enough so that it doesn’t fall off when the child shakes their head but loose enough that it doesn’t apply pressure.

7. Fasten the chin straps. They should lie flat against the child’s head, with a ‘Y’ at each earlobe (unless they are sewn together).

8. The straps should be comfortably fastened so that you can still fit one finger between the buckle and chin.

9. You can check the tension by asking the child to open their mouth and you should see the helmet visibly pull downwards.


  • Long hair should be worn at the base of the neck so that the helmet fits well.
  • Thick or woolly hats should be avoided with helmets as this may impact their effectiveness. There are alternative thermal liners made in children’s sizes that can keep the warmth in.
  • Check the fit every time. There is no ‘growing into’ a helmet, it should always fit well and be adjusted as needed. You may eventually have to re-measure their head and purchase a new helmet as they grow.
  • Don’t buy second hand. A damaged helmet will be compromised in terms of safety and it’s not something you can always tell just by looking at it.
  • If your child has a crash, you should replace the helmet. Some companies even offer a crash replacement discount.

Happy cycling!