How To Measure A Kids Bike – Tips and Tricks

Finding the right bike size for your kid is important, so your child can mount, ride, and dismount the bike as easily and safely as possible. A bike that’s too small will feel cramped, and one too big and your child’s feet won’t even touch the floor.

So, to help you choose the right bike, we’ve provided this comprehensive guide on how to measure a kid’s bike, including some helpful tips and tricks for you!


Types of Bikes

There are many different types of bicycles for kids, and even more so for adults. When it comes to children’s bikes, you’ll find cute stroller bikes and run bikes for toddlers, mini bikes with training wheels for young children, and 26” wheel bikes for tweens and teens. Essentially, these bicycle types are categorized based on age group and wheel size.

Kids Bike Sizes

Bicycles for children are classified according to sizes, which are determined by a couple of factors, most commonly being the wheel size, which is what manufacturers use to measure a kids bike size. If you’re wondering, “What size bike should I get?”, we’ve prepared a definitive guide for you:

How to measure a kid’s bike – step by step

If you’ve found (or already have) a bike for your little one, and want to find out whether it’s the right fit for him/ her, here’s a quick and easy way on how to size a bike using the bike wheel:

1.   Measure the diameter of the bike tire

One thing you can do is to measure the outer diameter of either the front or rear wheel (including the rubber tire) by using a measuring tape or ruler. Take several measurements to ensure that you’re getting the correct number.

2.   Check the tire for the size

Better yet, examine the tire and look for the markings indicating its dimensions. The first dimension should be the tire diameter (the second one is the tire thickness). For a more accurate measurement, you may opt to do both steps 1 and 2.

3.   Find the correct bike on the size chart

The wheel size roughly represents the kids bike size. Take a look at the size chart below and look for your bike’s wheel size.

Kids bike size chart

Here is a complete bike size guide so you can find the perfect bike for your kid:

Bike Type Run Bike Training Wheels Training Wheels 2-Wheel Bike 2-Wheel Bike Adult Bike
Wheel Size 8 to 12 inches 12 to 14 inches 16 inches 20 inches 24 inches 26 inches
Approx. Age 2 to 3 yrs 2 to 4 yrs 3 to 6 yrs 5 to 9 yrs 8 to 13 yrs 10+ yrs
Child Height 31 ½ to 40 inches 31 ½ to 44 inches 34 ½ to 48 inches 40 to 56 inches 46 to 66 inches 60+ inches
Approx. Inseam 15 to 18 inches 15 to 20 inches 16 to 22 inches 19 to 25 inches 23 to 28 inches 25+ inches

Kids bike sizes by age

As you can see above, we’ve got toddler bike sizes with small 8 to 14-inch wheels. These are mostly run bikes and stroller bikes, meaning, they come with a handlebar for you, and no pedals so your little one can just enjoy moving forward by “walking” while on a bike.

Once your kid is a little bigger and is eager to really ride a bicycle, a 14-inch bike with training wheels is a suitable bike for a 3-year-old, or a 16-inch bike for 5-year-olds.

2-wheel bikes with 20 to 26-inch wheels (or the less common 18-inch bikes) are best for bigger kids, tweens, teenagers, and adults. At this point, your child’s inseam and the bike height becomes important.

little boy on a kids bike

Additional bike size factors

As we’ve mentioned earlier, wheel size is not the only factor that affects the size of your child’s bike. So, for a better and more accurate bike fitting, take these other factors into consideration:

Height and inseam

You might be thinking you need to determine the bike frame size. Well, that mostly applies for adult bikes. When it comes to bicycles for the youth group, the height we are referring to is your child’s height, as well as his or her inseam. This is important since most children’s bikes don’t come with adjustable saddles and handlebars.

If you look at the size chart we’ve provided above, you’ll see how the child height and inseam play into effect.

How to measure the inseam

Your kid’s height alone is not definitive enough to help you pick the perfect bike size. For one thing, boys and girls of the same age and height may have different inseam measurements, so a bike that fits one may not work for the other.

To measure your child’s inseam, grab a thick book, and have your kid stand firmly on the floor, with feet slightly apart. Insert the book, spine side up, between his legs, until the spine rests firmly against his crotch. The distance from the floor to the book spine is his inseam.

Rider’s experience

How well your little one rides a bicycle is also important. For example, even if your child is big enough to ride a 20” bike, if he doesn’t know yet how to balance, then getting a bike with training wheels may be better and safer. Or, he may be on the smaller side, but already cycles like a pro. In this respect, factor in your kid’s riding experience when buying a kids bike.

Consider growth

Of course, you also need to allow some room for growth. You want your child to be able to use the bike comfortably even after a couple of years. Getting a bike that’s too small means your kid won’t be riding it for long. (But then again, don’t get a bike that your kid will have to wait a year to be able to ride.)

Bike equipment

Bonus facts: here is some must-have bicycle equipment so your kid can ride safely at all times, no matter what:

Reflectors and lights– while you wouldn’t want a toddler outside past sunset, older kids tend to love riding around the neighborhood during the early evenings, hence, reflectors and bright headlights are important.

Chainguard – little kids love to explore, but bike chains shouldn’t be included in their list of playthings. Chain guards should be present on a kids bike to prevent accidents like your kid’s foot getting trapped in the chain, or your kid touching the greasy chain.

Brakes– of course, with any bicycle, strong and fast brakes are important so your kid can stop as needed. So, when purchasing a bike for your little one, make sure that the brakes are good quality as well.


You can easily and confidently choose the right bike size for your child as long as you know what to look for. Of course, you can also choose to tow your kids so you can go on adventures together. If that sounds like fun, check out these best bike trailers.

To sum things up, the right way to measure a kids bike is by factoring in everything, from determining the wheel size, measuring your child’s height and inseam, then factoring in your child’s age and riding experience, as well as making room for growth.

That’s it! If you have any questions or comments, we’d love to hear them!

  • Category: FAQ