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Kids' Bike Sizing Guide + Sizing Chart

eric-awwy By Eric Awwy, 23 Jan 2021

While having a bike indeed matters than having none, ensuring that your kid has the right bike size matters. For a long time sizing bikes for kids has been through wheel sizes, which we now regard as outdated, insignificant, and flawed. If you wonder what the right bike size for your child is, our bike sizing guide (through the accurate kids’ bike sizing chart) will help you select the perfect kids’ bike sizes.

Noticeably, even bikes with the same wheel size can vary in terms of sizes. If you compare within or across brands, you will realize that while your child could comfortably fit on an 18” pedal bike by a brand, the same size might be limiting if you buy another brand. The same child might fit nicely on a size 16” or 20” bikes from other brands.

In an age where traditionally adult-bike manufacturers turn to the kids' bike market, some bike brands offer smaller (kid-specific) bikes while others offer larger bikes with the same wheel size.

For kids, jumping a single step or two for bike sizing is a big leap, affecting their cycling passion, which is why we have you a cheat sheet to help you find the perfect bike size for your child.  In it, we aim to main bike sizing for kids easier, and you will find an up-to-date kids bike sizing chart.

Why does the size of a kids’ bike matter?

Kids do not stay the same size for long, which is why you need to match the kid to the bike and not the other way round. A common puzzle is whether to buy a big bike for kids so that they can grow into it.

Finding the right size kids’ bike plays a huge role in instilling the thrill of being on two wheels while enjoying the many benefits cycling brings. You are not paranoid if you are obsessed with bike sizing for kids. Instead, you care enough for your child!

Kids’ bike size charts have become popular because parents are getting the essence of ensuring a good bike fit for the kids.

A right-fitting bike is easy to maneuver as the kid can control and balance it. The size of a bike for kids defines the level of comfort while on the saddle. The correct size of a bicycle allows your kid to get to the saddle and off the bike with ease by simply leaning the bike on one side.

Furthermore, finding the right size means that the child’s reach to the handlebars will be seamless. A poor bike geometry will continuously affect the child as they will be in a cramped position, limiting their pedaling.

Other times, if the bike is too big, the child will be so stretched out that they cannot control and balance the bike appropriately.

Since every child has a unique body physique – some taller while others shorter, some with long legs, while some with shorter legs, each child needs to have a fitting bike. Kids’ bikes are not one-size-fits-all. The arms, torso, and legs work together in sync to ensure a child rides a bike. With the right bike fit, cycling becomes fun, enjoyable, and welcoming. Naturally, the kids get to love their bikes more than video games, which is a win for you and your child.

Does age matter when choosing kids’ bike sizes?

Age counts in everything else but bike sizing for a kid-friendly bike. We say this because we have seen a six-year-old kid fit nicely on a 16-inch bike while a five-year-old fit on a 20-inch bike. This then puts to question the best indicator for the ideal size of a bike for kids.

The Sizes of Kids’ Bikes in the Market

The sizes of kids' bikes, measured in wheel diameter, include 12 inches, 14 inches, 16 inches, 18 inches, 20 inches, 24 inches, and 26-inch bikes.

A 12” bike has a 12 inches wheel diameter, and a 20-inch bike has a 20-inch long wheel diameter.

Noticeably, as the tire size increases, so does the frame of the respective bikes. Manufacturers can design kid-specific bikes for kids of different heights and ages using the wheel and frame size dimensions.

As per our research, we have discovered that sizes 12”, 16”, 20”, and 24” kids' bikes are the most popular in the market.

Even though the wheel size is a factor in selecting a kids’ bike, it IS NOT the best indicator when choosing the best bike for your child. It is, in fact, insignificant.

Wheel Size

The diameter of the Wheel


12 inches


14 inches


16 inches


18 inches


20 inches


24 inches


26 inches

Why the old-fashioned wheel sizes bike sizing approach does not work

Purchasing a kid’s bike back then relied on the size of the wheel of the kids’ bike. However, even though the bike sizing approach factors in height, it is never accurate.

We have always used the height vs. wheel size bike sizing charts. However, once we got into the bike stores or shops, we only ended up with a handful of bikes with the correct wheel size.

The size of a kids’ bike cannot solely be determined using the size of the wheel of the bike. Other factors such as the geometry and the size of the frame also play a critical role.

It is common to find bikes the same size in wheels, but with different measurements depending on the child's height they are designed for.

In this case, measurements such as seat height range, the wheelbase will vary – expect this when finding the right bike size for your kid among different brands.

The wheel size and height bike sizing method is also inadequate in that it does not give you information on whether or not your child will grow with their bike, be it a balance bike, first pedal bike, a second pedal BMX bike, or even a mountain bike.

This then leaves us with only one reliable, accurate, and tested method of sizing kids’ bikes – using the child's inseam.

Kids’ bike size chart

Wheel size







Approximate Age

2-3 years

2-4 years

4-6 years

5-8 years

8-11 years

10+ years

Inseam measurements (inches)







Height (inches)


37 – 44

42 – 48

45 – 54

49 – 59


How to find the right size kids bike for your child

We have already explained that the inseam combined with height is the ideal and reliable way of determining the right.

From our experience, when you combine seat height, age, and frame/wheel size, you end up with an actual bike fit for any given child.

If you are determined to get the perfect bike fit, you need to follow the steps below:

1. Measure the inseam of your child

Before even thinking of the size of the bike's wheels, you need to begin by measuring the inseam of your child. It is the only accurate factor that can help you fit a kid to a bike and not the other way!

Here are the simple steps you need to follow to measure a child’s inseam:

  • Ensure that your kiddo has their shoes on
  • Make the child stand straight against the wall with their feet slightly apart
  • You can measure the length of their legs and the leg inseam, which is the distance from the crotch of the child’s pants to the floor.
  • For accuracy, place a book (hardbound) in between the legs of the child
  • Raise the book until the book spine firmly touches the crotch of the child
  • Level the book with the floor
  • Measure the distance from the floor to the spine of the book, which gives you the INSEAM.

How to measure a child's Inseam

With the inseam, you can now narrow down to the exact wheel size that gives you the best range of kids’ bikes to select from. It is best to identify one to two-wheel sizes that align with the child's inseam given the inseam range. If this is the case, we recommend going for the larger wheel sizes in the range because of stability and save you money as they have room for growth. However, there is an extent to which you can do this, as discussed later in this article.

2. Decide on the wheel size that is appropriate for your child

As we intimated before, the diameter of the wheels of the kids’ bikes defines the sizing of the bikes. The smallest kids’ bikes in the market are size 12” bikes, which have a 12-inch diameter, while the bigger kids' bikes are either 26” or 27.5” bikes. As soon as the kids outgrow the size 24” bikes, they are ready for adult size bikes.

However, we have noticed a trend where manufacturers are making smaller youth-oriented size 26-inch bikes.

Determining the wheel size appropriate for your child helps narrow it down to the size of the bike that your child might need. If you have a taller child, you would go for bigger kids’ bikes instead of shorter or petite kids who will prefer smaller kids’ bikes.

Now, with the wheel size out of the way, we get into the next step, which entails finding the perfect seat height.

3. Use the Inseam, set the right seat height

When buying a bike, a parent’s wish is always to get a kids’ bike that currently suits the child but leaves some room for growth. Even if you want a bike that lasts long, considering that kids’ bikes cost more sometimes, buying the right size now matters.

A larger bike will be a hurdle to the child, and so is a smaller bike. In both cases, the child will not master cycling and will certainly ditch it for a sedentary lifestyle.

With the knowledge of what size bike best fits your child, you must further consider your child's riding experience or ability.

The seat height correctly helps in getting the proper fit of a kids’ bike. If a child is a beginner, intermediate, or pro, the seat height will be set differently. The same case applies to kids using training wheels.

The seat height is defined as the distance from the top of the seat to the ground. If you combine it with inseam, height, age, frame size, and wheel size, you are guaranteed to get a great fit of a bike for your kiddo.

Set the seat height depending on riding ability/experience

Considering that two kids of the same age can possess different riding skills, abilities, and experiences and learn through different bikes, setting the seat height matters a lot.

Balance Bike

The kids need to put both of their feet flat on the ground with their bodies in an upright walking position for a balance bike fit.

Ensure that the child's knees are slightly bent to allow efficiency for running with the pushbike.

For the sizing, the seat of the balance bike should be set at 0.5-1.5 inches below the child's inseam. We compiled a balance bike sizing and buying guide for you.

First Pedal Bike

Beginner riders who are balance bike graduates should sit on the bike seat with their heels lifted off the ground 1-2 inches max. Ensure that timid riders lift their heels 1 inch while aggressive or athletic rides raise it beyond 1 inch but not more than 2 inches. The essence is to have an efficient standover height and allow a comfortable pedaling position, which will enable kids to touch down easily after braking. However, in most cases, setting the first pedal bike’s seat the same as the inseam works- we’ve never had a complaint.

Second Pedal Bike

As these are already aggressive/athletic riders, they need to tippy-toe 2-4 inches with timid preferably setting their heel raises at 2 inches while aggressive riders 3 inches or less with the kid seated on the saddle.

Another right way is to have the seat height set 2-3 inches above the child's inseam. The aim here is to attain maximum leg extension for efficient pedaling.

First bike with training wheels

We are against training wheels as they delay mastery of cycling. Instead, we prefer balance bikes as they teach balance and control and then pedaling later.

If training wheels are your preference, ensure that the seat is 0-3 inches above the child's inseam. If your kid is timid, set the saddle lower enough to touch the seat with their feet flat on the ground.

Online resources to help you choose perfect Kids' bike sizes

Kids’ bikes are not one-size-fits-all for given ages, which is why the inseam is set at approximate ranges. Many other factors affect bike fitting. For instance, a given kid might have a specific torso size that changes how the child fits into a bike.

We are trying to say that even though using an inseam is accurate, you need to consider other bike sizing indicators such as seat height, riding experience, age, and height to solve the bike-size puzzle.

There are online bike sizing resources that combine all these aspects to ensure that you settle for the right size bike for your kiddo. Here are some kids’ bike sizing resources that you can check out

What happens when your kid is in between wheel sizes?

Finding and eventually choosing the perfect bike that fits your kid brings tranquility, especially if the inseam and the seat height have led you to it. However, when your kid stands at either the lower or upper end of the recommended bike sizes given the inseam, wheel size, and height, you will be one uneasy person in the world.

If this happens, most parents end up worrying whether to pick a kids’ bike size that fits currently or choose a bike that a child will grow with.

Money matters a lot, but for kids’ bikes, size dominates the choice. It is not a matter of who is calling the shots! One piece of expert advice that has worked for most parents consulting with us is that: If the child is closer enough to the next size of a bike, jump right into it – buy the next size. We find this useful if the child is on their second bike, which means they are confident, stable, and can control a bike.

If your kid is an aggressive or athletic rider and has the muscle to handle heavier and bigger bikes, you can choose a bike whose seat height can be adjusted to suit their level of prowess better.

Smaller bike sizes are preferably suited for timid riders. We have no problem spending on a smaller bike that a child would outgrow soon because we believe that the right size of a bike is indicated by the comfort on the bike when purchasing and not at a future date. Mostly, if the inseam is on the lower side, we often get second-hand used kids’ bikes, which saves us some dime for the next size bike in the coming months.

If anything, do not plan for an unassured future too much; buying a larger kids’ bike to force them to grow into can put an end to their cycling zeal, get the right size. If you’re lucky enough that they can grow with it, good for you!

Although size matters, it is not exclusive!

Although size is the first thing any parent would think before settling for a kids’ bike, there are undoubtedly other factors that you must consider as well. As we cover in our definitive kids’ bike buyer’s guide, you need to consider factors such as:

  • Cost
  • Geometry
  • Brakes
  • Tires
  • Training wheels/stabilizers
  • Weight
  • Frame material
  • Color

No standard governs bike sizing for kids’ bikes, which makes the sizing confusing. However, our comprehensive bike sizing guide and chart will guide you through. To date, we have helped hundreds of parents find perfectly fitting kids’ bikes. Our happiness is to see more kids on the bikes. Look deeper into these aspects of choice by reading our ultimate and definitive kids' bike buying guide

Word on Safety on the Bike

Once you decide the right size of the bike, research, and purchase one, remember to spare and budget for a helmet too. Properly fitting kids’ helmet is mandatory safety gear. And like bikes, you must get the right size of a helmet for your kid’s head. Do not assume that the helmets, being designed for kids, are one-size-fits-all, no. we have already put up a definitive helmet buying guide to help you select the best helmet for your kid.

Do not just spend so much time picking the perfect bike while little time purchasing a helmet, it is as important an accessory as the bike is. It is as good a worthwhile investment just as is elbow and knee pads, bike lights, cycling shorts and jerseys, and bike pumps.

Now that we know size matters, where do you buy?

As the best website that tests, researches, and reviews then recommends kids’ bikes, we have reviewed hundreds of bikes and bike accessories. Here is a list of the bikes we have reviewed that can help you narrow down to the specific kids’ bike:

We have respective comparison charts for balance bikes and pedal bikes, which can help you narrow down to the best kids’ bike suitable for your kiddo. You can choose a bike from a brand you love, or parents love that, and we’ve further made it easy to find a bike that best fits your child.

Bottom Line

Here are some take-aways:

  • Ensure that you get the right size of a bike for your child at the right time.
  • Kids’ bikes are not one size fits all.
  • Bike fit determines whether your kid will love their bike or ditch it for other stuff.
  • Always research before purchasing and while doing so, engage your kids and experts, if necessary.
  • It is not a must that you get a high-end kids’ bike, some mid-range and budget bikes deliver performance and components like the high-end bikes.
  • Kids do not need much of a variation, so the cruisers, MTB, or BMX bikes can do.

Kids grow at different rates, which means different bike sizes will fit the same age range differently.

In this respect, the only accurate, tested, and guaranteed method to find the right bike size for your child is through measuring their inseam.

The method helps you get a kids’ bike that your child can grow with and one that they are comfortable, confident, and happy to ride.

As per experts, the right bike fit matters to a kid, which is why we compiled this kid’s bike sizing guide with charts and explanations that you can follow before finally settling on a specific kids’ bike brand.

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