Bike Helmet Size Guide for Children

It’s tough picking out a helmet for your kid when they come in deliberately vague size ranges like “child,” “toddler,” and “youth.” A toddler might fit into child-sized helmets, or a kid might fit into adult-sized helmets. Each helmet has an inch range, but that doesn’t mean it will fit. Often the circumference will match up, but the helmet isn’t comfortable. So, how can you tell if your child’s helmet fits? This guide will walk you through the essential steps to figuring this out.

Step #1: Find “Just Right”

Think of the story “Goldilocks and the Three Bears” to guide you along in the process. You need to find a helmet that’s too small, then one that’s too big, to know what’s just right.


Try a helmet that’s too small first.

Your kiddo will let you know it isn’t comfortable. A helmet that’s too small won’t be able to sit flush with the top of the head.

A helmet too small will stop well above the ears before the head is finished rounding out. Any retention system (more on this later) typically will need to be as loose as possible. The chin strap might not be able to clip, or if it does, it’ll usually put a lot of pressure on the underside of the rider’s chin.

If the helmet pinches the sides or won’t fully sit on the head, go with something bigger. But what does too big look like?

Next, go big or go home!

A helmet that’s too big looks and feels like a bucket strapped to their chin. It’ll wobble and shake with any movement. The chin strap might be as short as possible but will still slip past the chin. If it has a retention system, it might be as tight as possible but won’t hold the head securely. Most dangerously, an oversized helmet could be able to slip forward, obscuring vision.

Ahhhh, now try on “just right.”


A “just right” helmet won’t flop around on their head. It will sit flush with their scalp with minimal gaps. A small amount of movement is inevitable, since a correctly fitted helmet will end up moving on the scalp a little if jostled. The critical thing is that it stays firmly in place and doesn’t obscure vision.

Step #2: Personalize the Fit

Once you have the right helmet size, you need to personalize the fit. Helmets come with a few different methods to help get the fit more exact.

Tighten the dial.

Specialized uses a dial located on the back of the helmet, which tightens a flexible plastic cage. This cage holds the helmet securely on the head.


Secure the Velcro.

Similar to the dial fit, a Velcro strap on the Bern Nino & Nina helmet ensures a snug fit on properly sized helmets.


Adjust the padding.

Some helmets come with interchangeable padding in a range of thicknesses to adjust the fit. In this system, you either use the large pads or the small pads to fit the helmet snugly.


Step #3: Wear It Properly

A correctly fit helmet won’t do its job if it isn’t worn properly.

Align the front of the helmet.

The front of the helmet should be just above the brow. At the eyebrows or lower will obscure vision. High above the eyebrows means the helmet isn’t sitting on the head correctly and won’t provide proper protection.

Place and secure the chin strap.

Always tighten the chin strap. It should be snug but not tight. Two fingers should be able to fit between the strap and the chin. And remember to fasten the chin strap.


This might seem obvious, but the chin strap should always be clipped. An unclipped helmet—or a strap not under the chin—is the same as no helmet.

Step #4: Let Your Child Choose Their Favorite!

Finally, ask your child which one they want. Get the helmet they feel comfortable in. If it doesn’t fit, they won’t wear it. Same goes for style. If they think the helmet is dorky, they won’t wear it. If you find a helmet they like, they are more likely to use it.

Now Encourage Your Kid(s) to Ride, Be Safe, and Have FUN!

Shop our kids’ helmets online, or roll into your local ERIK’S and let our experts help you find the perfect helmet for your kiddo.