Bike Size Chart Kids’, Fit by Inseam, Height + Measuring Tip

Few rites of passage loom larger in a child’s mind than riding their first bicycle. Yet regardless of whether it’s their first or fifth bike, the quality of their riding experience is largely determined by how well the bike fits his or her particular body. There is no more important factor in your purchasing decision for your child’s (grandchild’s, niece’s, etc.) bicycle than buying just the right size. Plug two simple measurements into our easy-to-use charts below to give your child a head start toward safe and happy cycling with the right size bike.

AD - Elevate Your Kids' Bike Riding Experience:

At a Glance

  • Finding the best possible fit for your child’s bike provides the control and maneuverability a child needs to learn to ride well and safely, and to derive maximum enjoyment from their biking experience.
  • The most essential measurement for calculating the perfect bike size is your child’s inseam. Correlating the inseam to the bike’s stand-over height provides the child with maximum control and comfort. 
  • The other crucial measurement for providing your child with the best bike fit is overall height, a solid indicator of the necessary wheel size for a kids’ bike.
  • Inseam and height measurements can be obtained easily, quickly,  and practically simultaneously with no more than a ruler, a pencil and a tape measure.
  • Since there’s no telling what height or how physically coordinated and well-developed a child may be at any given age, age is not a reliable, objective criterion for sizing a bike.

Most important kids’ bike size criteria

The two indispensable measurements you’ll need from your child to ascertain the best possible bike size are inseam and overall height. Inseam, a measurement used to find the best fit in clothing as well, represents the vertical distance from the ground to the crotch of a person standing upright. Inseam is the No. 1 criterion for finding the best possible fit for a child’s bike. To custom-fit a bike to your child, consult our “Kids bike size by inseam chart” below.

The other important measurement you’ll need is your child’s overall height. Not essential to closely form-fitting the bike, overall height is a useful measure that can provide general orientation and steer you toward a bike of the appropriate wheel size. Once again, you need go no further than our chart below, “Kids’ bike size by height”.

Want to calculate the age of someone in years, months, days, or even hours?

Taking inventory: kids’ bike sizes 

When it comes to sizing up potential bikes, the most common, standard reference for bike size is wheel diameter. Ergo, when someone says a bike is 20” – perhaps the most common kids’ bike size of all in the U.S. – they mean both the front and rear wheels measure 20” across from rim to rim. Other popular sizes include 12”, 16”, and 26”, but the choice is almost endless, and someone even occasionally comes up with a  new size. 

But simply because your child is a height that calls for a 20” bike doesn’t mean they can ride any 20” bike. Even more important than tire size in finding the perfect fit in a kids’ bike is stand-over height: the distance from the top tube, or uppermost horizontal bar spanning from the saddle to the handlebars, to the ground. Here, the child’s inseam measurement is all-important, because the differential between this measurement and the bike’s stand-over height will dictate how much comfort and control while riding the bike.

Standing astride the bike, the child should have 1”-2” between their crotch – the top of their inseam – and the top tube. So if their inseam is 24”, they can comfortably ride a bike with stand-over height 22”-23”.

Sizing up your kid for best bike fit

So all that’s left to do is to ascertain the child’s inseam and height. Fortunately, you can take these two measurements easily and almost simultaneously.

For height

  1. Simply have the child stand comfortably upright with his or her back against a wall,
  2. Hold a ruler or other thin, flat implement horizontally across the top of the child’s head and against the wall,
  3. Make a mark (erasable or indelible for posterity – your choice!) where the ruler intersects with the wall, and
  4. Measure in inches the vertical distance from the mark to the floor. 

For inseam

  1. Using the same ruler and with the child still standing upright against the wall,
  2. Hold the ruler loosely under their crotch and against the wall,
  3. Again mark where the ruler intersects with the wall, and
  4. Again, measure the vertical distance from the mark to the floor. Voilà! You have the child’s inseam.

Kids bike size chart by height

Find your child’s height on the chart to then determine what bike wheel size, often referred to as the bike’s size, is best for them.

Child height (Feet)Child height (cm)Wheel size
2’9”-3’1″85-90 cm10 inches
3’1”-3’3″90-100 cm12 inches
3’3″-3’7″100-110 cm14 inches
3’7″-3’8″110-115 cm16 inches
3’8″-4’0″115-120 cm18 inches
4’0″-4’5″120-135 cm20 inches
4’5″-4’9″135-145 cm24 inches
5 Feet and tallertaller than 145 cm26 inches

Kids bike size chart by inseam

Locate the inseam range on the chart that will enable you to find the best possible fit in stand-over height.

Inseam length (Inch)Inseam length (cm)Wheel size
12”-14″85-90 cm10 inches
14”-17″35-42 cm12 inches
16″-20″40-50 cm14 inches
18″-22″45-55 cm16 inches
20″-24″50-60 cm18 inches
22″-25″55-63 cm20 inches
24″-28″60-72 cm24 inches
28 inches and longer72 cm and longer26 inches

Minor adjustment for balance bikes

You may be shopping for your child’s first push or balance bike, i.e., a two-wheeler sans pedals or training wheels designed to teach balance which a child propels by pushing off on the balls of their feet. In this case, a minor modification to the foregoing measurement method is required. The top of the inseam should be aligned with the saddle rather than the top tube, with no more than a 1” gap between crotch and saddle. This unique height ratio of saddle height is to enable your child to push off on the balls of his or her feet.

This saddle has the right height for the kid riding its bike

Debunking age as a criterion

Finally, the time has come to debunk one attribute  all-too-often named as a determinant for sizing bikes for children: age. As long as the child’s physical measurements falling within the parameters outlined on the charts well-matched to the dimensions of the bicycle, age in itself is no objective criterion for determining how well a child will ride. At this point, whether the child is physically coordinated and mature enough in judgment for the bike at hand is perhaps best left up to the child’s parents or guardian. Age alone is not a reliable criterion.

Kids bike size chart by age

AgeWheel size
2 years10 inches
3-4 years12 inches
4-5 years14 inches
5-6 years16 inches
6-8 years18 inches
7-9 years20 inches
9-11 years24 inches
11-14 years26 inches

Find Ski Size Charts or Snowboard Size Chart here.


What size bike do I need for my child?

The size that will best fit your child can be calculated by factoring the child’s inseam and overall height. Take these measurements, then consult the corresponding charts.


What size bike do I need for my 5-year-old?

The best size will be calculated by the child’s inseam and height, regardless of age. See our Kids’ bike size by inseam and height charts.


Can I use the same measurements for a toddler’s balance bike?

A balance or push-bike is an exception in that inseam should be aligned with saddle height rather than standover height, to enable children to better propel themselves by pushing off on the balls of their feet. Find even your toddler’s ideal-sized balance bike with the charts herein.


Why is my child’s bike size so important?

Equipping your child with the  best possible fitting bike will grant them the control and maneuverability to learn to ride easily, safely, proficiently, and happily.