Which size kids’ bike should I buy?

August 29, 2018 (Last update: November 10, 2026)

How do I determine the right size kids’ bike for my child? What should you look out for when buying a kids’ bike? Children often hit a sudden growth spurt and from one day to the next their bike is too small. Raising the saddle can help for a while, but in most cases it simply means they need a bigger kids’ bike. But how do you figure out the right kids’ bike size for your child?

Image result for kids’ bike

How do you determine the right kids’ bike size?

A child’s age usually doesn’t say much about the right bike size. One 4-year-old can be much taller than another. There’s no difference between girls and boys either. So how do you decide on the right bike size? In general you determine the correct bike size for your child in 2 ways:

By measuring the inside leg length
By using their clothing size

For adults, the right bike size is expressed in frame size; for children it’s in inches. Those inches indicate the tyre size, not the frame size.

Choosing the right kids’ bike size: measuring inside leg length

The so‑called inside leg length is the distance from the top of the saddle to the ground. Make sure the saddle is in its lowest position. When your child grows again, you can simply raise the saddle. Once you know the inside leg length, you can use a handy chart to find out which wheel size in inches matches your child’s height.

Inside leg length	Tyre size
43 cm	12 inch
53 cm	16 inch
58 cm	18 inch
61 cm	20 inch
63 cm	22 inch

Choosing the right kids’ bike size: clothing size

An even easier way to determine your child’s bike size is by using their clothing size. Children’s clothing sizes already correspond to height in centimetres, so it’s relatively simple to work out the correct tyre size. The chart below gives you a clear overview.

Kids’ bike size chart
Age	Clothing size	Saddle height	Tyre size
2.5 - 4 years	98 - 104	43 cm	12 inch	12 inch boys’ bike	12 inch girls’ bike
4 - 6 years	104 -110	53 cm	16 inch	16 inch boys’ bike	16 inch girls’ bike
4 - 8 years	110 - 116	58 cm	18 inch	18 inch boys’ bike	18 inch girls’ bike
6 - 8 years	116 - 122	61 cm	20 inch	20 inch boys’ bike	20 inch girls’ bike
5- 9 years	122-128	63 cm	22 inch	22 inch boys’ bike	22 inch girls’ bike
8- 12 years	128 - 140		24 inch	24 inch boys’ bike	24 inch girls’ bike
10 - 14 years	140 - 152		26 inch	26 inch boys’ bike	26 inch girls’ bike

So working out the right bike size for your child is actually pretty simple. Make sure you regularly check whether the handlebar and saddle are still at the right height. Children grow so fast that it’s worth checking every month whether the bike needs adjusting. Make sure your child doesn’t have to pedal with fully stretched legs and can easily reach the ground to get off the bike.

Where can I buy a cheap but good kids’ bike?

These days there are countless online bike shops where you can order a kids’ bike in just 3 clicks. They’re often delivered the next day and assembling them is usually a piece of cake. On Marktplaats you’ll also find a wide range of second‑hand kids’ bikes.