Kids bike size chart and calculator
Enter your child's inseam, or height if you do not have it, to get the wheel size. The chart compares Academy Sports and BikeRadar by wheel size, age, height and inseam.
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Enter your child's inseam or height above to get shopping links for the wheel size.
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Inseam is the most reliable measurement; age and height overlap a lot between wheel sizes. Academy's chart has no 18 inch row, so those figures come from BikeRadar only. BikeRadar's figures are the minimum inseam for each wheel size.
| Wheel size | Academy: age | Academy: height | Academy: inseam | BikeRadar: age | BikeRadar: minimum inseam |
|---|---|---|---|---|---|
| 12" | 2–3 | 36"–39" | 13"–17" | 2+ | 12" (30 cm) |
| 14" | 3–5 | 37"–44" | 15"–20" | 3+ | 15" (38 cm) |
| 16" | 4–6 | 41"–48" | 16"–22" | 4+ | 16" (41 cm) |
| 18" | — | — | — | 5+ | 18" (46 cm) |
| 20" | 5–8 | 45"–54" | 19"–25" | 6+ | 20" (51 cm) |
| 24" | 8–11 | 49"–59" | 23"–28" | 8+ | 23" (58 cm) |
| 26" | 10–12+ | 56"+ | 25"+ | 10+ | 25" (64 cm) |
The two sources are not identical: Academy's 16 inch row allows an inseam from 16 to 22 inches, while BikeRadar's 16 inch minimum is 16. If the inseam sits in an overlap, pick the size where your child can put the balls of both feet on the ground comfortably, and have them sit on the bike before you buy.
How to check the fit
- Measure the inseam. Riding shoes on, a book between the legs against the groin, floor to book top, three times.
- Check standover. The child's inseam should be at least equal to the bike's standover height; a bit more clearance is more comfortable (Academy).
- Seat height depends on the stage. Academy suggests about 1 inch above inseam on a balance bike, 0 to 3 inches above on a bike with training wheels, level with the inseam on a big-kid bike (feet flat when stopped), and 2 to 4 inches above for experienced riders on tiptoes.
- Do not oversize. BikeRadar warns that a bike that is too big makes a child nervous and harder to control; some brands offer trade-up schemes as the child grows.
Questions
What size bike does a 5 year old need?
Age is the weakest guide. Academy lists 14, 16 and 20 inch wheels for overlapping ages around 5, and BikeRadar starts 18 inch bikes at about 5. Measure your child's inseam and use the calculator or the table: inseam decides the wheel size, not age.
Should I buy a bigger bike so my child can grow into it?
The sources disagree. Academy says to choose the larger wheel if a child falls between sizes so they can grow into it. BikeRadar advises against buying a size up, because an oversized bike can make a child nervous, lose confidence or overbalance. If you do go up, make sure the child's feet can still reach the ground.
How do I measure a child's inseam for a bike?
Have the child wear their riding shoes, place a book between their legs against the groin, and measure from the floor to the top of the book. Repeat three times (Academy).
What is standover height?
It is the height of the bike's top tube or frame where the child stands over it. Academy says the child's inseam should be at least equal to the bike's standover height, and more clearance is more comfortable.
What size is a balance bike?
Both Academy and BikeRadar put balance bikes at 12 inch wheels, for about ages 2 and up, with a minimum inseam of about 12 inches.