Kid Bike Calculator & Finder 🚲
Getting the right kids bike size can make the difference between your child loving to ride and struggling with it. Our finder matches your child’s inseam to every reviewed bike in our database — balance bikes through 24″. No inseam yet? Browse by wheel size.
How to Measure Your Child’s Inseam
Kids Bike Finder
Results include two key indicators:
· Room to Grow — the inches of seat height adjustment remaining. More inches means the bike fits longer as your child grows.
· Our Score — a 100-point rating from our hands-on testing rubric covering frame design, components, braking, fit range, and weight. See our rubric score breakdowns on our best bikes pages for 12″ & 14″ bikes, 16″ bikes, 20″ bikes, and 24″ bikes.
Why inseam — not age or height?
Age charts are a starting point, but kids of the same age can differ by several inches in leg length — which is what actually determines whether they can reach the ground safely. Inseam measurement takes about 60 seconds and gives a far more accurate fit.
If you want to understand the full reasoning behind seat height, rider experience levels, and how to fine-tune the fit, our Kids Bike Sizes Guide covers it in detail but for most parents, entering the inseam below and letting the calculator do the work is all you need.
Frequently Asked Questions
Size down for first-time riders so they can touch the ground flat-footed. Size up for experienced riders who are comfortable on the brakes.
You can, but it’s less accurate. Kids of the same height can have very different leg lengths. Inseam takes less than a minute to measure and gives a much better fit.
Yes. First-time pedal bike riders need to be able to place both feet flat on the ground while seated. The calculator accounts for this when you select “Learning Rider”
The calculator only includes bikes we’ve personally tested, reviewed and recommend. If we test a bike and don’t like it, you won’t see it here.
Could I get a suggestion? My son right now is 6.5yo, 3’11” / 48 lbs., inseam of 21″. He currently rides a Scoot XL (when he outgrew his balance bike 1.5 yrs ago, he was unsure of pedals and asked for another balance bike). The Scoot XL is still a good fit, but he’s been curious about pedals lately and actually asked for one (for Christmas). He fits into the Priority Start 16 and the 20, and in your review, your tester for the 20 was similarly sized. Which would you suggest? It would probably be easier to go from a 14″ bike to a 16″… but he’s also kind of hung up on wanting a bike with a “racy red frame” like Henry Huggins. Budgetarily speaking, having 6 (!) whole inches of room (Start 20) to grow also sounds fantastic, but I know 4″ of room (Start 16) is nothing to scoff at either. Thanks 🙂
I would go with the Start 20. With a minimum seat height of 20.5″, it will fit him now while still giving him time to grow. Seeing that he is getting close to pedaling, he will likely outgrow the Priority 16 pretty quick and the 20″ does offer the awesome red :). Upon getting his new bike, I would make sure not to put the pedals on and let him ride it like his Scoot XL until he gets used to the feel of the larger bike. Once he is comfortable, navigating the larger size, put the pedals on and he will likely be pedaling within a day or so. The trick to helping him quickly transition from a balance bike to a pedal bike is not to let him pedal from a standstill. Have him get the bike going by running and then start to pedal. Bikes are MUCH more stable at higher speeds, so learning to pedal at a higher speed is significantly easier than at lower speeds. Hope this helps!
When I put in 18” inseam I am getting mostly 12 and 14” wheels (in budget brands I am interested in). Elsewhere on this site (as well as on NYT wirecutter, etc) I’ve seen 16” wheel recommended for 4-6 year olds, plus I’d like some room to grow (the seat height on these 12 and 14” wheelers max out very soon for an 18” inseam. But when I go ahead and select the 16” wheel size, I don’t get anything within my budget. While I can take what I think I’ve learned from my research and go find one (retrospec koda plus 16”), but it defeats the purpose of using the tool. If I hadn’t known better and had bought a 12”wheel with a seat that my granddaughter may out-grow in a couple of months a lot of us would have been pretty disappointed.
Sorry the tool wasn’t able to help you out. The Retrospec Koda Plus 16” does show up in the finder if you select “Experienced Rider”, but it won’t show up if you have “First-time Pedal Bike Rider”. When learning how to pedal and ride a bike, first time pedal bike riders need to be able to touch the ground with their full foot while seated on the saddle. This allows them to comfortably stop the bike with their feet to prevent crashes and calm nerves.
Since you entered an inseam of 18”, the tool won’t offer the Retrospec for first-time riders. Seeing as the tool is based on code and we have to give it strict guidelines, it’s not perfect. In reality, since most people under-measure their child’s inseam, I would recommend getting the Retrospec Koda Plus 16” for a beginning rider with an 18” inseam. If it is slightly too tall, I would suggest having your granddaughter ride the bike with the tallest shoes she has.
Hope that helps!
Thank you!
Not sure inseam
That’s pretty common, most parents don’t know their kids inseam, but dialing in the right fit for your child is MUCH more accurate using inseam. Here’s a quick video to show an easy way to measure inseam: https://youtu.be/RXuvO6uaU4Y?si=8-q5jTpkUFZfsSGI
It looks like Woom 2 & Woom 3 bikes (most at least) display an inaccurately large saddle height on the tool here which is then contradicted on the review page. Other bikes generally seem accurate between tool and review.
You are absolutley right, thank you for bringing that my attention. The maximum inseam recommendations were listed as the instead of the max seat height for both the woom 2 and 3, they have been fixed.
Why don’t you rate Forth (Park) Bikes anymore?
Forth Bikes are not CPSC certified for sale in the US, so legally they can’t be sold here. Nothing wrong with the bikes, they just need to be certified before we can recommend them.
Hi, The information on the Pello REYES and Pello REYES SE are backwards. the SE is a single speed and is the cheaper bike. I’m not sure about the other information.
Thanks so much for letting me know! I got it fixed.