Kids Bike Size Chart (FULL Size Guide)

One of the first toys that children often get when it comes to growing up is a bicycle. This is often a small cruiser bike with trainer wheels, which allows them to better prepare for riding their bigger bike as they grow older. The ultimate kid’s bike size chart would help you determine which bike your kid would need for their size and age.

What Size Bike Should My Kid Buy? Many people simply want to know the bike size that their kid needs. However, kids’ bikes are sized slightly differently than adult bikes, and much like mountain bikes, they would rely on the size of the wheels and not the frame. You should understand that your kid’s bike size would vary depending on the age and height of the child.

To help you buy the perfect bike for your kid, we will be looking into the different frames and bike sizes. This would give you a solid idea of what your kid would need and the specific bike that would work for them. We will break down how you should go about selecting the right bike for your kid and understanding the needs.

Kids Bike Size Chart

Understanding The Kids Bike Size Guide: Finding The Right Size Bike

Before I show you the chart itself, we should look at some of the fundamentals that make a kid’s bike size. The following guidelines are what we often use when we want to know what to look for. They should work in conjunction with the bike size chart. Here are a few of the fundamental things to keep in mind:

1. Understanding The Right Wheel Size

For kids’ bikes, it is easy for you to get confused when selecting the right bike. You would need to start with the diameter of the wheel size, which would make it possible to see the numbers. The smallest bikes I could find on the market today are around 12 inches in size when it comes to the wheels. However, they go up to 26 inches for most bikes, with the larger 31-inch bikes being for the tallest of individuals.

The sizing can differ significantly and many manufacturers also create 26-inch bikes, but in a youth size. Due to the youth sizing, they are large when it comes to the wheels, but the smaller frame would also make them functional.

Kids’ balance bikes are even smaller and some of these bikes start at 10 inches in wheel size. However, the most common size for these kid’s bikes would be around 12 and 14 inches in wheel size.

2. Using Estimates

The one thing that a bike chart does well is using estimates. Ideally, you would want to be physically present and I have noticed that when I sit on a bike or ride it around the block, it can get a feel for the size. This would immediately tell me if the bike is ideal for me or if I need a different bike to get me going.

However, this is not always possible and most people would rely on estimates of age and height. You can start with this method and in most cases that would be accurate. However, you should do some research on the bike manufacturer to find out whether or not the bike you have selected would be functional and useful.

3. How And What Should You Measure When Determining Size?

If you are choosing the route of measurement and taking on the different aspects like guessing and trusting the bike charts, you need to understand what you should measure. It is important to do this with accuracy and you should not guess when it comes to your kid and understanding what they would need.

You want to start by measuring the inseam and the height of your kid. Once you have these measurements, it would be better to convert these measurements into inches. It would work far better to have the inches for these selections. Most top manufacturers and sellers online would market their products in inches.

However, the road bike is different and as your kid starts aging up, they might choose road bike as their favorite discipline. If this is the case, you would not be working with the wheel sizes, but rather the frames, which would be measured in centimeters.

4. Check The Bike Specs

Once you are done with the measurements, you should write them down on paper. Once you have them down on paper, you would need to use them with the bike specs.

If you check any online retailer, you should see a bike size guide to looking at when you choose a bike. This is where you would want to use the inseam and the height to determine the right bike. Not every manufacturer would use the inseam when it comes to the bike specs. For this, you should check the height and see how it correlates with buying a bike. Here are a few important things to understand when buying a bike:

  • Check The Wheel Size: The most important aspect that you are probably looking at would be the wheel size. Make sure that the wheel size correlates with what you are looking for in your bike.
  • Seat post Heights: The next step would be to check the seat post heights. This is not always possible, but you should be able to call the manufacturer to get this information. It would tell you how much the seat can be adjusted. The seat height could make a massive difference when you ride a bike.
  • Frame Design: The way the frame is designed would vary from bike manufacturer to bike manufacturer. Some might have a bulge in the frame, which could make it slightly higher. You should also consider the overall size and the design specs of the frame.
  • Trainer Wheels: This one might be a bit off-topic, but having good trainer wheels can make a big difference. However, they should be comfortable and should not lift the bike too much. The Geminiman Bicycle Training Wheels are some of the best that you can find on the market today.
Kids on bike with Trainer Wheels

These are four of the most important things that you should look out for and they will make a significant difference when selecting a bike. Keep in mind that not all of this information might be readily available and it might cost you to get in touch with the manufacturer to ensure you get all the info you might need.

Accurate Kids Bike Size Chart For Buying A Bike For Your Child

Now that you have a better understanding and a way of calculating the right size for your kids’ bike, you should also look at how the most common charts are set up. The most common bike charts would be similar for most bike brands. Here is what you can expect when it comes to a traditional bike size chart from an online retailer.

Bike Size (Wheels)Recommended AgeHeight (Inches)Inseam (CM)
12-inches2-32’10”-3’4”35-42 cm
4-inches3-43’1”-3’7”40-50 cm
16-inches4-53’7”-4’0”45-55 cm
18-inches5-63’9”-4’3”50-60 cm
20-inches5-84’0”-4’5”55-63 cm
24-inches7-114’5”4’9”60-72 cm

This would be one of the most basic charts for buying a kids’ bike and you would often find that it would vary depending on the bike you choose and the brand. Some might have sizes in between these and when looking at adult bike sizes, they would also be different from the traditional options on the market today.

We would recommend using these sizes to ensure that you have the ultimate bike to use and ensure you have the ideal bike for your kid.

Key Features To Look For When Finding The Right Size Bike For Your Kid

Aside from looking at all the features that make up the size of the kids’ bike, you should also consider looking at additional things like special features. The following section would give you additional insight into a kid’s bike. This would allow you to use the chart with these features and make sure that the bike your kid chooses is functional:

Bike Type

When it comes to kids’ bikes, we don’t often look at things like the mountain bike or the road bike. These bikes are a bit more complex and they often work best for adults. As your kid starts to age, you would be more dependable on these different bikes, especially when they have made their mind up on the specific discipline.

It would often be best if you could look at the balance bike. The balance bike is specifically designed to help children get started. They also feature trainer wheels, which could easily be attached to the bike and these would make it more functional and easier to ride. The balance bike is the best bike for your child on the market.

A bike with 16-inch wheels might not be ideal for road bikes and this would often be uncomfortable. The road bike also lacks the ability to have a bike with training wheels. The ultimate option for a road bike would be a 24″ bike that features solid designs and the seat height of a bike can be adjusted to get the right size.


You don’t need to go buy a top-branded bike for your kid when they are learning to ride. Even when buying the cheapest bikes, brands like Trek and Specialized would still be some of the brands that you pay top dollar for. However, cheaper brands like Schwinn or even Mongoose are known for being affordable bikes.


While the carbon fiber bike is by far one of the best bikes that you can buy, it is not worth it to go to such lengths for a kids’ pedal bike. If you buy a bike, you should make sure it has a sturdy frame, which could be made from steel or aluminum. The cheaper steel frames are often the best. They also allow for accurate height and inseam measurements.

Bike Fit

Finally, the perfect bike fit is one of the most important aspects to consider and each bike would look and work differently. If there is one thing that you can take from all the advice we have given you and you have access to the bike, you should consider the following. You want your kid to stand over the frame of the bike with feet flat on the ground.

The easiest way to make sure that your bike will fit is to get close to the bike and have a physical feel for the bike. It might take some time for you to get used to the bike, but it should work as a treat for most people to ensure value.

kids bike on the road

How Do Adult Bike Sizes Differ From Kids’ Bike Sizes?

As mentioned, you might come across a few situations where the adult bikes and the kids’ bikes are different. For the most part bike manufacturers would try to make sure that they can have the sizes synch up with one another and have them be similar to the adult sizes to avoid confusion.

In cases when the sizes would differ, the manufacturer would often refer to the frame. This means that instead of using the wheels for determining the size of the bike as you would find in many cases, you would now have the frame.

Frame sizes can be different and a 20-inch frame could be much lower than your 20-inch wheels if the bike does have smaller wheels.

Understanding BMX Bike Sizes

The one difference that we always come across is the size of the BMX bike. The BMX bike would often be 20 inches when it comes to the wheels. However, the frame would be the most important aspect here to consider. Here is a basic chart to keep in mind when buying a BMX bike:

Micro MiniUnder 53’6”-4’0”
Expert XL10-135’3”-5’7”

These would be the sizes that you would consider when looking for a BMX bike. You will notice that they tend to be universal for the most part, which means they would be similar for all bikes. The BMX bike is a great beginner bike for kids.

Kids Bike Sizing Summary

When choosing the ideal bike for your needs, you should always look at the most important features and the size. In this guide, we believe we have covered all the aspects of buying the best kids’ bike. However, I would love to see some of your comments when it comes to the ultimate kids’ bikes on the market today.

About Martin

I am Martin, I am the author of this blog. My main interests include cycling. That's why this blog was created. I have always been interested in technology and how bicycles are made, so I built one myself.

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