What Size Bike For Kids? (A Guide For Boys & Girls)

Sizing bikes for your child can be a confusing affair because of the bewildering array of bike sizes that cater to kids of all age groups.

However, this can be easily accomplished by having a basic understanding of how kids’ bicycles are sized and what to look for when deciding on the right size bike for the child.

At the same time, it bodes well for the kid to have the right-sized bike as that would play a role in how the kid perceives biking to be and lean into this wonderful experience.

A good experience with bikes and biking in the early years is crucial for the child to develop an appreciation for this activity and the outdoors.

This would help keep the kid fit instead of clamming up inside the house and engaging in sedentary activities.

How Are Kids Bike Sized?

Kids’ bikes are sized based on the wheel size, unlike adults’ bikes which are sized based on the frame as well as the wheel size.

The wheel size is the measurement of the diameter of the wheels.

kids bike sizing

For eg., a 20-inch bike for kids denotes the diameter of the wheels which measure 20 inches from one point on the wheel to another point that lies exactly opposite to it.

Kids Bikes

What Size Bike For Child?

Although kid’s bikes are denoted by the wheel size, take that only as a general guideline when bike sizing for your kid.

A better gauge would be the age and height of the child.

As kids can vary very much in terms of their height and weight for the same age, going with wheel size as the metric may not be an ideal method to select the right bike.

Also, factor in the growth spurt of the child as otherwise you would find yourself in the market for a new bike in a couple of months’ time. Kids can grow out of the bikes before they get to grow into their bikes.

The below bike size chart gives a suitable estimation of the recommended height and age for all kids’ bike wheel sizes.

Bike Size Chart:

Bike Wheel Size  Height (Inches) Age (Years)
10 InchToddler2 – 3
12 Inch34” – 40”3
14 Inch36” – 42”3 – 4
16 Inch36” – 46”4 – 5
18 Inch40” – 50”5 – 6
20 Inch43” – 55”6 – 7
24 Inch51” – 59” 8 – 9
26 Inch58” – 63”10 – 13
girls bikes

Boys And Girls Bike Size Difference:

From a functional aspect, there is no difference between girls’ and boys’ bikes other than that of aesthetics.

Both boys and girls can ride the same bike. It’s mostly a marketing gimmick where you’ll get to see girls’ bikes where the only difference would be in terms of the color palette of the bike and some additional accessories like baskets etc.

Some bikes may sport a lowered top tube on girls’ bikes which makes it easier for the child to hop on and out of the bike.

kids bike

Other Factors To Consider When Selecting A Bike Size For The Child:

Weight Of The Bike:

The weight of the bike is an important factor that can play a big role in how the child experiences the bike and is something that is overlooked by adults when purchasing a bike for the kids.

A kid’s physique is not developed well enough, unlike adults, to lug around weights that are heavy in proportion to their body weight.

So a slight increase in weight can translate into a big effort for the child.

The materials used on the bike are the major factor. Steel tends to be heavier than aluminum and can add weight to the bike.

Carbon fiber is the lightest but is expensive and is mostly found on high-end performance bikes.

Likewise, aluminum is costlier than steel and is also less prone to rusting.

Bikes from the big box retail brands that are cheap tend to be heavy and unwieldy.

Extra features such as gearing can also add to the weight of the bike.

The Fit & Geometry Of The Bike:

The fit & geometry of the bike is also a factor that needs to be taken into account when sizing a bike for kids.

Bikes with poor geometry such as that found on the big box retail brands can play spoilsport and ruin the fun of biking for the child.

There are a couple of aspects of geometry that can be broken down into

  • Standover Height
  • Reach & Stack
  • Q-Factor

Standover Height:

This is the measurement of the height of the bike from the floor to the top tube (the tube that connects the seat post to the front of the bike near the fork).

This distance from the floor to the top tube indicates how much room the kid has when standing over the bike.

Ideally, this gap should be a couple of inches more than the standover height of the child.

This optimum height imparts confidence to the kid, especially when they are learning to bike.

Reach & Stack:

Reach & Stack roughly refers to the space between the triangular frame of the bike – between the saddle at the back, the fork in the front, and the bottom bracket at the bottom (the part where the cranks are attached).

Bike Reach And Stack

This space has to be optimum for the rider to feel confident and comfortable with the bike.

Too much space and the child will be seated way back on the saddle and would feel less confident with the handling.

Too little space and the kid would feel cramped resulting in overexertion to propel the bike forward which may also result in the knee touching the handlebars during the top of the stroke.


This is the distance between the two pedals, roughly denoting the width of the bike. The lower the Q factor the better the balance.

As the Q factor increases, the kid will have to splay the legs while pedaling resulting in overexertion.


Below are some commonly asked questions and answers regarding bike size for children of various ages.

Bike Size For A 5-Year-Old:

A 16-inch bike would be ideal for a 5-year-old who is between 36 and 46 inches tall.

However, if your child is taller than an average 5-year-old and is growing fast you can also test out an 18 or 20-inch bike that may be a better fit.

Click here for a detailed article on bike size for 5-year-olds.

Bike Size For 10-Year-Olds And Above:

A 26-inch bike is suited for a 10-year-old. However, by the time kids are 10 years, they are going to vary very much in terms of their height and size.

If your kid is shorter than an average 10-year-old, then consider a 24-inch bike.

Likewise, if your child is taller, then opt for a 26-inch adult bike. Note that a 26-inch bike is also the recommended size for an 11 or 12-year-old too.

Click here for a detailed article on bike size for 10-year-olds.

Bike Size For A 6-Year-Old:

For a 6-year-old between 43 to 55 inches tall, a 20-inch bike is the recommended size. Nowadays, there is also an 18-inch wheel size available that is trying to bridge the gap between 16 and 20-inch bikes.

So, depending on where your child falls in the height chart, you can also test out and see whether an 18-inch would be a better fit.

Click here for a detailed article on bike size for 6-year-olds.

Bike Size For A 4-Year-Old:

Depending on the height as well as experience with biking, a 4-year-old can ride a 16-inch or a 14-inch bike.

If your kid is shorter than an average 4-year-old or hasn’t learned biking, then a 14-inch would be a good option to consider.

Click here for a detailed article on bike size for 4-year-olds.

Bike Size For A 8-Year-Old:

A 24-inch bike is the recommended size for an 8-year-old who is between 51 and 59 inches tall.

If the kid is shorter than an average 8-year-old, then consider a 20-inch bike, and likewise if taller, a 26-inch kid’s bike can be considered.

Click here for a detailed article on bike size for 8-year-olds.

Bike Size For A 7-Year-Old:

For a 7-year-old, a 20-inch bike would be a good fit. If the kid is smaller than an average 7-year-old, you can also consider an 18-inch bike.

However, note that 18-inch bikes are a new entrant and not that of a common size.

Click here for a detailed article on bike size for 7-year-olds.

Bike Size For A 3-Year-Old:

A 12-inch balance or pedal bike would be the ideal size for a 3-year-old depending on whether the kid has learned to balance or not.

If the child has not learned to balance, start off on a 12-inch balance bike.

For experienced 3-year-olds, you can opt for a 12-inch or 14-inch pedal bike depending on the confidence level of the child.

Click here for a detailed article on bike size for 3-year-olds.

Bike Size For A 9-Year-Old:

A 24-inch bike would be suitable for a 9-year-old who is between 51 and 59 inches tall. If your kid is taller, you can also opt for a 26-inch kids’ bike that may fit better.

Click here for a detailed article on bike size for 9-year-olds.

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