Kids BMX Frame Size Calculator

Kids BMX Frame Size Calculator

Finding the right size BMX for kids can be tricky because they are not sized the same as normal kid’s bikes. To make life simple for you we have made a kids BMX size frame size calculator.

Rider height:

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

Kids BMX Size Calculator (Plus Size Guides & Charts)

Kids BMX Frame Size Calculator
Kids BMX Frame Size Calculator

Race BMX Sizing Chart

Rider HeightFrame SizeToptube LengthStem LengthBar RiseBar WidthCrank LengthGearing
4’4″ & underMicro15″ – 16.5″Mini: 25mm – 35mm2″ – 2.5″20″ – 22.5″145 – 155mm41-43 / 16
4’2″ – 4’10”Mini16″ – 17.5″Mini-Mini XL: 30mm – 40mm2″ – 3.5″21″ – 23.5″155 – 165mm41-43 / 16
4’6″ – 5’1″Junior17″ – 18.5″Mini XL-Expert: 40mm – 45mm3″ – 5″22″ – 25″160 – 175mm42-43 / 16
5’0″ – 5’4″Expert18.5″ – 19.5″Expert-Pro: 43mm – 48mm5″ – 7″25.5″ – 27″170 – 175mm42-43 / 16
5’2″ – 5’6″Expert XL19.5″ – 20″Expert-Pro: 43mm – 48mm6″ – 7″25.5″ – 27″170 – 175mm42-43 / 16
5’3″ – 5’8″Pro20″ – 20.5″Pro: 50mm – 55mm7″ – 8″27″ – 28″175 – 180mm43-44 / 16
5’7″ – 6″Pro XL20.5″ – 21.25″Pro XL: 50mm – 55mm8″ +28″180 – 190mm44 / 16 & over
6″ & overPro XXL21.25″ – 22″Pro XXL: 52mm – 60mm8″ +28″180 – 190mm44 / 16 & over

How Do You Size a Race BMX?

The best way to size a race BMX is to look at a size chart that uses your height and inseam to determine your ideal size range.

What Age Should You Start BMX?

Children can start BMX as young as 3 years old if they have the right bike and are conformable at riding. All kids are different, so it mainly comes down to their height and ability. in recent years pump tracks have become popular with all ages, and they are also a great way for your child to learn the basics of BMX. Our little one started riding the local pump track on his balance bike and then made a seamless transition onto pedals.

Kids BMX Frame Size Calculator for all ages

How High Should a Kid’s BMX Seat Be?

BMX saddle height depends on personal preference. Most people don’t sit down and pedal while riding BMX, so the seat does not need to be up too high. Many BMX riders prefer their saddles as low as possible (out of the way), and others like them to be a few inches up, which can help the rider know where the bike is in relation to their legs.

Does Frame Size Matter BMX?

In short yes, correct BMX frame size is very important. No matter if you are a child or an adult we all come in a wide range of sizes. BMX brands offer a good range of frame sizes for kids. However, when it comes to larger adults there are fewer options available.

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

Only size up if your child is closely between two sizes. Otherwise, try and stick to the recommended size because if the bike is too big it will often be hard work for your little ones to handle. At the end of the day getting the correct size bike is important because it will allow them to gain confidence and more importantly have fun!

Can Girls Ride BMX?

Of course, girls can ride BMX! There are also many professional female BMX riders. Riding BMX is a sport that’s open to all no matter your age, gender or ethnicity.

How Much Does It Cost to Start Bmx?

Starting BMX riding can start from as little as $200 for a used BMX, and can go up to $2000+ for a high-speed new BMX. Many people new to BMX normally want to know if it’s worth spending money on a high-end well spec’d BMX. The simple answer is yes, but within reason. Most riders won’t have the need to get the highest spec’d BMX possible, but if you buy a cheap BMX you will most likely not enjoy it as cheap BMXs are usually heavy and no fun ride. So at a minimum, go for a BMX from a known BMX brand that has 3-piece cranks.

Final Thoughts on Kid’s BMX Size

When looking for the correct size kid’s BMX you can either try our kid’s bike size calculator at the top of this page, or you can check out the kid’s BMX frame size chart alow on this page. Remember, try and stick to the recommended frame size, sizing up can be tempting but you’re only going to make like hard for your little one.

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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.