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.

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.

• Kids bike size chart by inseam
• Kids bike size chart by height

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”.

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.

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.

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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.

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

FAQ