Kids Bike Size Calculator (Plus Size Guides & Charts)

Let’s face it, when it comes to choosing the correct kid’s bike size it can be confusing, to say the least!

To begin with, it’s important to note that kid’s bikes are sized differently than adult bikes. Kids’ bikes are sized by wheel size, not frame size like adult bikes. You also should be aware that sizing does vary between brands, factors like the frame reach and standover height can vary considerably.

Kids Bike Size Calculator

Kids Height :
Wheel size:

How to Use The Kids Frame Size Calculator

1) Enter the kid’s height in the kid’s bike size calculator.

2)  Measure the child’s leg length/inseam. (measure from the ground to the top of the inside of their leg)

3) If the leg length/inseam is within the recommended range then this is the correct frame size.

If their leg length is:
⬆ More than the recommended range consider going up a frame size

⬇less than the recommended range consider going down a frame size

inseam for Kids Bike Size Calculator

Kids Bike Sizes Chart

When choosing a kid’s bike size you should measure their height and inseam. If the child is close to the next size of bike you might want to consider sizing up, so they don’t grow out of the bike in no time.

Kids Bike Sizes Chart

How High Should a Kid’s Bike Seat Be?

The height of a child’s bike seat depends on their inseam length (leg length), and the child’s level of experience. Getting the seat high correct is one of the most important factors to consider when setting up a child’s bike and will help ensure correct from the beginning.

The height of a child’s bike seat is measured from the ground to the top of the seat/saddle. We also have an adult Bike Saddle Height Calculator.

Balance Bike Seat Height

The child’s knees should be slightly bent while the child is seated on a balance bike. This slight knee bend will allow the child to scoot but not drag their feet too much.

SIZING TIP: Set the seat height to around 1.0 – 1.5″ bewlow the childs inseam/leg length, ensurnig slight knee bend.

Bike with Training Wheels Seat Height

Training wheels can be a good option, especially if the child is feeling nervous. As the bike will stay upright on its own, the seat height should depend on how confident the child is feeling. For nervous children set the saddle height so their feet are flat on the ground, and for more confident children set the saddle height so the child is on tiptoes. Remember not to set the saddle too high as children often naturally like to drag their feet to slow down.

SIZING TIP: With training wheels set to 0 – 2″ above the childs inseam/leg length. Ensure they can easiy touch the gound.

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Beginner Pedal Bike Seat Height

When children are learning to pedal a bike it’s very important they can comfortably touch the ground. To begin with, pedalling comfort and efficiency is not a concern, it’s more about building confidence.

SIZING TIP: Set the seat height the same height as the childs inseam/leg length, or even slightly below.

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Experience Bike Rider Seat Height

Once a child is comfortable at getting on the bike, confidently pedalling, and then stopping in a controlled manner, then you can start to think about slightly putting up the saddle to help improve pedalling comfort and efficiency. Remember the child should always be able to touch the ground easily on tiptoes.

SIZING TIP: When a child is a confident bike rider you can put their seat height up to 1 – 3” of obove their inseam.

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Training Wheels vs Balance Bike (Which Is Better?)

Most of the time balance bikes are better than training wheels (stabilizers). This is because balance bikes allow children to learn to balance while moving, whereas training wheels keep the bike upright no matter what. The skills children learned from balance bikes normally allow a natural transition onto a pedal bike later on. Here’s some more info on trainig wheels on WIkipedia

Cheap VS Expensive Kids Bikes? (is Spending More Worth It?)

Many people wonder with kids growing so fast is it worth spending the money on a more expensive kid’s bike. Well, the answer is it depends on your budget and how into biking your family is. The big advantages to more expensive kid’s bikes are they are lighter which makes the bike easier to ride, plus they are usually much more durable, which can also be an advantage if you’re considering more kids. Lastly, expensive kids’ bikes have a good resale value meaning you’re not likely to loose much. So expensive kid’s bikes are worth the money, however, if you’re budget won’t stretch don’t worry as kids will have loads of fun, no matter the bike!

Should I Size up When Buying a Kid’s Bike?

Yes, consider sizing up if they’re in between sizes. If not then stick to the recommended size. This is because if a children’s bike is too big it can make it challenging for them to learn and build confidence. I know it can be tempting to save money and get a bike they will grow into, however, a bike that’s slightly too small can be more confidence-inspiring than a bike that’s too big.

Which Size Kids Bmx Should I Get?

Which Size Kids Bmx Should I Get?

To make life even trickier, kids’ BMX sizes are different to normal kids’ bikes. So all the information above does not apply to Kids BMXs.

When it comes to BMX there are two common types:

  1. Stree/freestyle BMX (used for skatepark, street and flatland riding)
  2. Race BMX’s (used on BMX track)

Both of these BMXs also have different sizing systems.

With Stree/freestyle BMX you generally choose the wheel size down from what you would choose for a traditional kid’s bike. For example, If they normally ride a 20inch bike, they would ride an 18inch Stree/freestyle BMX.

With racing BMX bikes they all use 20inch wheels, but the frame size changes depending on their height. You can use our kid’s race BMX frame size calculator here.

Final Thoughts on Kid’s Bike Size

Children naturally come in different shapes and sizes, they grow incredibly fast, and there is a whole range of different abilities- so choosing the correct kid’s bike size can be tricky. So to make things simple, use our kid’s bike size calculator (at the top of this article) and then read the section on saddle height. If you can get these two factors right you should be pretty close to the ideal fit.

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Peter Ballin

Pedro is the primary writer on the site. He’s raced downhill and enduro at a high level, spannered at mountain bike world cups, and also written a book called Mountain Bike Maintenance. He’s appeared in both print & online major media publications across the Uk, France, and Japan (and even appeared on French Television). He’s made his living from bikes in various forms, from mountain bike guiding in France and Spain, Trail building in New Zealand and Canada, and working as a bike mechanic in the French Alps for many years. Pedro loves a good adventure and is often settling random challenges like riding down Mount Fuji, swimming across Lake Geneva, and hitchhiking across America.