- By: James Grear
- Last updated:
Finding the right size bike for your kid is crucial. A poorly fitting bike can lead to pain whilst riding, ultimately making cycling a horrible experience for any youngster.
Getting to grips with and learning to cycle is hard enough, so a properly sized bike will allow them to focus on developing their cycling skills whilst enjoying their time on two wheels.
Fortunately, I’ve put together this kids bike size guide so that you can quickly determine what size bike your child requires.
Keep reading, and you’ll learn precisely how to choose the right size bike for a child, along with many other helpful bike sizing tips.
At What Age Can a Kid Ride a Bike?
The age at which a child can start riding a bike varies. Some children develop their balancing skills sooner than others, but the sooner your child starts learning to ride a bike, the sooner they’ll master the skills needed to cycle without support.
On average, children between the ages of 3 and 8 can start riding a bike. As they spend more time on two wheels, they’ll become more confident, eventually being able to cycle without stabilisers or other support.
Note that the 3-8 age range is average. However, some children may take to two wheels before the age of three, and some may require a little longer to build the confidence to try cycling.
If your child wants to start cycling at an earlier age, a balance bike can be a great way to build confidence for children as young as 18 months!
Otherwise, if your child is ready to ride a pedal bike, they may benefit from using training wheels (stabilisers) to help them balance.
Now that we’ve covered the best age to start cycling let’s look at how to properly measure kids bike sizes.
How to Measure Kids Bike Size
If your child needs a new bike, you’ll need to measure their inseam and height to determine the best size bike for them.
Age can also be used to find a kids bike size, but this is a less accurate sizing method.
Unlike adult bikes, kids bikes are measured by the wheel size, not the frame size, don’t get the two mixed up, or you’ll end up with the wrong size bike!
Just before we get into the nitty-gritty, I wanted to let you know two essential rules when choosing a bike size for a child:
- A bike that your child likes is much more likely to be ridden and enjoyed. Whilst we can’t all afford the latest and flashiest bikes, a bike that makes a child excited to cycle will be money well spent.
- Whilst you may be tempted to buy a bike that your child will grow into, an ill fitting bike is no fun for anyone to ride. Similarly, a large bike that’s too heavy for a kid to manoeuvre will likely put your them off cycling for good.
How to Measure Kids Bike Size By Inseam
A kid’s inseam measurement is the length of their inside leg, from the top of their crotch to the ground.
The inseam measurement determines how tall a bike needs to be for a rider to touch the ground with their feet whilst sitting on the bike seat.
The short steps below will talk you through the most accurate way to measure a child’s inseam for a bike.
- Have the child stand with their shoes on and back to a wall, feet shoulder-width apart.
- Take a sturdy book and place the book as high as comfortable possible between their legs, with the book’s spine pressed flat against the wall.
- Whilst holding the book firmly in place, ask the kid to step away from the wall.
- Using a measuring tape, measure the distance between the top of the book and the ground.
- This length is your inseam. Take note of it to avoid having to remeasure.
How to Measure Kids Bike Size by Height
The steps below are the easiest way to measure a kid’s height for finding their most suitable bike size:
- Have your child put the shoes they wear for cycling on.
- Direct them to stand straight up with their back against a wall, feet shoulder-width apart.
- Place the book’s spine on the top of their head and press the book against the wall.
- Use measuring tape from the bottom of the book.
- This measurement is your kid’s height. Take note of it so you won’t need to measure again soon.
Most Accurate Kids Bike Size Chart (Height & Inseam)
Once you’ve taken your child’s height and inseam measurements, you can use the table below that’ll help you find the most suitable bike size.
At the end of the article, I’ve included a Bike Size FAQ section, so if you have any questions when deciding upon the best bike size for your kid, take a look.
| Rider Height | Inseam (Inches) | Suggested Kids Bike Wheel Size | ||
|---|---|---|---|---|
| 2'10" - 3'4" | 86cm - 101cm | 14" - 17" | 35cm - 42cm | 12" Wheels |
| 3'1" - 3'7" | 94cm - 109cm | 16" - 20" | 40cm - 50cm | 14" Wheels |
| 3'7" - 4'0" | 109cm - 122cm | 18" - 22" | 45cm - 55cm | 16" Wheels |
| 3'9" - 4'3" | 114cm - 130cm | 20" - 24" | 50cm - 60cm | 18" Wheels |
| 4'3" - 4'5" | 122cm - 135cm | 22" - 25" | 55cm - 63cm | 20" Wheels |
| 4'5" - 4'9" | 135cm - 145cm | 24" - 28" | 60cm - 72cm | 24" Wheels |
| >4'9" | >145cm | >28" | >72cm | 26", 27.5" & 700c Wheels (adult bikes) |
How to Measure Kids Bike Size By Age
If you’re purchasing a bicycle for a child but don’t have access to their measurements, one way to estimate their bike size is by using their age.
It is important to note that this is not the most accurate way of measuring, as bike size by age only uses the average height of children.
If your child is much taller than average for their age, they would probably fall into a different wheel size.
Nonetheless, here are the charts that illustrate the best wheel size by age for boys and girls, using the average height of boys and girls in the USA and UK.
Just below either table, I’ve simplified the data for those who might find the tables confusing.
Boys Bike Size Chart by Age
| Rider Age | Rider Height | Suggested Boys Bike WheelSize | |
|---|---|---|---|
| 2 years old | 34.2" | (86.8 cm) | 12 inch wheels |
| 3 years old | 37.5" | (95.2 cm) | 12 inch wheels |
| 4 years old | 40.3" | (102.3 cm) | 12 inch wheels |
| 5 years old | 43.0" | (109.2 cm) | 14 to 16" wheels |
| 6 years old | 45.5" | (115.5 cm) | 14 to 16" wheels |
| 7 years old | 48.0" | (121.9 cm) | 18 to 20" wheels |
| 8 years old | 50.4" | (128 cm) | 18 to 20" wheels |
| 9 years old | 52.5" | (133.3 cm) | 18 to 20" wheels |
| 10 years old | 54.5" | (138.4 cm) | 24" wheels |
| 11 years old | 56.5" | (143.5 cm) | 24" wheels |
| 12 years old | 58.7" | (149.1 cm) | 26", 27.5" & 700c Wheels (adult bikes) |
A two-year-old boy of average height – 34.2″ (86.8cm) will find a bicycle with 12-inch wheels most comfortable.
A three-year-old boy of average height – 37.5″ (95.2cm) will find a bicycle with 12-inch wheels most comfortable.
A four-year-old boy of average height – 40.3″ (102.3cm) will find a bicycle with 12-inch wheels most comfortable.
A five year old boy of average height – 43″ (109.2cm), will find a bicycle with 14 to 16 inch wheels most comfortable.
A six-year-old boy of average height – 45.5″ (115.5cm) will find a bicycle with 14 to 16-inch wheels most comfortable.
A seven-year-old boy of average height – 48″ (121.9cm) will find a bicycle with 18 to 20-inch wheels most comfortable.
An eight-year-old boy of average height – 50.4″ (128cm) will find a bicycle with 18 to 20-inch wheels most comfortable.
A nine-year-old boy of average height – 52.5″ (133.3cm) will find a bicycle with 18 or 20-inch wheels most comfortable.
A ten-year-old boy of average height – 54.5″ (138.4cm) will find a bicycle with 24-inch wheels most comfortable.
An eleven-year-old boy of average height – 56.5″ (143.5cm) will find a bicycle with 24inch wheels most comfortable.
A twelve-year-old boy of average height – 58.7″ (149.1cm) will find a bicycle with 26″, 27.5″ or 700c wheels most comfortable.
Girls Bike Size Chart by Age
| Rider Age | Rider Height | Suggested Girls Bike Wheel Size | |
|---|---|---|---|
| 2 years old | 33.7" | (85.5cm) | 12 inch wheels |
| 3 years old | 37" | (94cm) | 12 inch wheels |
| 4 years old | 39.5" | (100.3cm) | 12 inch wheels |
| 5 years old | 42.5" | (107.9cm) | 14 to 16" wheels |
| 6 years old | 45.5" | (115.5cm) | 14 to 16" wheels |
| 7 years old | 47.7" | (121.1cm) | 18 to 20" wheels |
| 8 years old | 50.5" | (128.2cm) | 18 to 20" wheels |
| 9 years old | 52.5" | (133.3 cm) | 18 to 20" wheels |
| 10 years old | 54.5" | (138.4 cm) | 24" wheels |
| 11 years old | 56.7" | (144cm) | 24" wheels |
| 12 years old | 59" | (149.8cm) | 26", 27.5" & 700c Wheels (adult bikes) |
A two year old girl of average height – 33.7″ (85.5cm), will find a bicycle with 12 inch wheels most comfortable.
A three year old girl of average height – 37″ (94cm), will find a bicycle with 12 inch wheels most comfortable.
A four year old girl of average height – 39.5″ (100.3cm), will find a bicycle with 12 inch wheels most comfortable.
A five year old girl of average height – 42.5″ (107.9cm), will find a bicycle with 14 to 16 inch wheels most comfortable.
A six year old girl of average height – 45.5″ (115.5cm), will find a bicycle with 14 to 16 inch wheels most comfortable.
A seven year old girl of average height – 47.7″ (121.1cm), will find a bicycle with 18 to 20 inch wheels most comfortable.
A eight year old girl of average height – 50.5″ (128.2cm), will find a bicycle with 18 to 20 inch wheels most comfortable.
A nine year old girl of average height – 52.5″ (133.3cm), will find a bicycle with 18 to 20 inch wheels most comfortable.
A two year old girl of average height – 54.5″ (138.4cm), will find a bicycle with 24 inch wheels most comfortable.
An eleven year old girl of average height – 56.7″ (144cm), will find a bicycle with 24 inch wheels most comfortable.
A twelve year old girl of average height – 59″ (149.8cm), will find a bicycle with 24 inch wheels most comfortable.
How to Measure Bike Size For Teenagers
Measuring a bike size for a teenager is done precisely the same as when measuring for a child.
If your teen isn’t of average height, you should locate a column in on of the bike size charts displaying the closest match to their height.
Otherwise as you’ll find in the table below, anyone above the height of 57″ (145cm) is now ready for an adult bike with full size wheels!
You can view our adult bike size guide here if your child needs a larger bike!
| Rider Age | Rider Height | Suggested Teen Bike Wheel Size | |
|---|---|---|---|
| 13 years old | 61.5" | (156.2 cm) | 26", 27.5" & 700c Wheels (adult bikes) |
| 14 years old | 64.5" | (163.8 cm) | 26", 27.5" & 700c Wheels (adult bikes) |
| 15 years old | 67.0" | (170.1 cm) | 26", 27.5" & 700c Wheels (adult bikes) |
| 16 years old | 68.3" | (173.4 cm) | 26", 27.5" & 700c Wheels (adult bikes) |
| 17 years old | 69.0" | (175.2 cm) | 26", 27.5" & 700c Wheels (adult bikes) |
| 18 years old | 69.2" | (175.7 cm) | 26", 27.5" & 700c Wheels (adult bikes) |
| 19 years old | >69.2" | >175.7 cm | 26", 27.5" & 700c Wheels (adult bikes) |
BMX Size Guide - For Kids & Adults
Unfortunately, when it comes to BMX’s, none of the above applies, apart from the two golden rules stated toward the top of the article.
BMX bikes use a smaller frame than other types of bikes, meaning the tables displayed above this point don’t apply to them.
The table below is the most accurate way to size a BMX bike for kids and adults.
| Rider Height | Suggested BMX Bike Frame Size | ||
|---|---|---|---|
| <4' | <122cm | Micro-Mini | 15" - 16" |
| 4' - 4'6" | 122cm - 142cm | Mini | 16" - 17" |
| 4'4"- 4'10" | 137cm - 149cm | Junior | 17" - 18.5" |
| 4'8" - 5'4" | 147cm - 163cm | Expert | 18.5" - 19.5" |
| 5'4" - 5'10" | 163cm - 181cm | Pro | 20" - 20.5" |
| >5'10" | >181cm | Pro-XL & Pro-XXL | >20.5" |
Kids Bike Size Guide - FAQs
Unlike adult bikes measured by their frame size, a child’s bike is measured by its wheel size.
Generally, kids wheels sizes range from 12-inch wheels to 24 inches.
If your child has outgrown the height and inseam size of a 24-inch wheel, then they are ready to graduate to an adult bike.
Stabilisers have their pros and cons. They are a great way to introduce young children to cycling as they prevent bikes from falling over, reducing the risk of injury.
However, once a child has become accustomed to stabilisers on their bicycle, they may struggle when you remove the stabilisers.
Instead of leaving the stabilisers on their bike for an extended period of time, it’s a good idea to remove them once they’ve built a good level of cycling confidence.
If they aren’t confident without them, you can run alongside them as they cycle unassisted and prevent them from toppling by holding them or the underside of their saddle.
If you’ve used the kid’s bike size guides above to pick the best size bike for your child, but their height, inseam or age falls in between two categories, don’t panic.
Your best option is to take the larger size of the two. Kids will grow into the bigger bike, and because they’re suitable for either size, it won’t be uncomfortably large for them.
If you’ve found any of the above kid’s bike size charts too confusing or are still unsure which bike size is best for your child, a bike fit is your next best option.
Go into any bike store, and they’ll happily help you find the perfect bike size for your kid.
This way, you’ll know for sure that the bike will fit your child, and they’ll enjoy their time riding it!
Is the ground hard? Yes.
Can falling from a bike cause a severe head injury? Yes.
Should children wear a bike helmet when cycling? Yes.
Cycling is a potentially dangerous sport that can result in serious injury if the correct precautions aren’t taken.
From the beginning of their cycling life, kids should be taught that bikes and helmets go hand in hand, just like cars and seat belts.
Helmets save lives.
A 12-inch bike is suitable for riders that are 2 to 4 years old and of average height (34″ – 40″).
If your child is taller than average, they may need a 14″ bike.
Our kid’s bike size charts provide more information.
A bike with 14 or 16-inch wheels will be suitable for riders that are 5 to 6 years old and of average height (42.5″ – 45.5″).
If your child is taller than average, they may need an 18-inch bike.
Or, if they’re shorter than average height, they may require a 12-inch bike.
Our kid’s bike size charts provide more information.
A bike with 16 or 14-inch wheels will be suitable for riders that are 5 to 6 years old and of average height (42.5″ – 45.5″).
If your child is taller than average, they may need an 18-inch bike.
Or if they’re shorter than average height they may require a 12-inch bike.
Our kid’s bike size charts provide more information.
A bike with 18 or 20-inch wheels will be suitable for riders that are 7 to 9 years old and of average height (47.7″ – 52.5″).
If your child is shorter than average, they may need a 16-inch bike.
Or, if they’re taller than average height, they may require a 24-inch bike.
Our kid’s bike size charts provide more information.
A bike with 24-inch wheels will be suitable for riders that are 10 to 11 years old and of average height (54.5″ – 56.7″).
If your child is taller than average, they may need a 26-inch bike.
Or, if they’re shorter than average height, they may require a 20-inch bike.
Our kid’s bike size charts provide more information.
A bike with 26-inch wheels will be suitable for riders that are 12 or older, with an average height of (59″).
Once a child reaches 12 years old or is taller than 59″ (150cm), they’re ready to use an adult bike. If they’re taller than average, they may benefit from using a 27.5″ bike.
Or, if they’re shorter than average height, they may require a 24-inch bike.
Our kid’s bike size charts provide more information.
Conclusion - Kids Bike Size Guide
This guide took a while to put together, so I hope you’ve found it helpful in choosing a bike size for your kid.
You should now understand how to choose a kid’s bike size, how to measure a bike for a kid, and the dos and don’ts of choosing a new kid’s bike.
If I’ve left you with any unanswered questions, leave me a comment below, and I’ll get back to you right away.
I’ve also put together a detailed bike size guide for adults & kids that have outgrown child-sized bikes, read it here.
Otherwise, when buying a bike for your kid, don’t forget they’ll need a bike lock to secure it safely.
Just for you, I wrote an article which reviews the best lightweight bike locks, suitable for use with children’s bikes. Have a read.
As always, lock it or lose it.
Ciao for now.
Kids Bike Size Chart - Image
Recent Updates:
- 8th Mar 2024: Updated article layout for improved readability
2 Responses
I’ve had the hardest time teaching my 10 year old to ride a bike and I think I can blame it mostly on my improper instructing. He’s having a terrible time with balance and steering I don’t know what size to teach him on. His height would be a 24″ bike, but we’ve tried a little BMX bike and 24″. Which is better for just learning? I get frustrated and then he gets frustrated and then it’s no fun. We’ve been trying for 2 summers now with minimal progress. What do you suggest?
Hi Lisa!
Have you tried using stabilisers on your son’s bike? These are definitely a worthy investment for anyone looking to get used to balancing on two wheels. There are many factors that play a part in selecting the best bike, so it’s hard for me to give guidance without seeing your son riding. However, if he’s comfortable whilst riding, the size shouldn’t be a huge problem.
I recommend trying stabilisers before anything else.
Best,
James