Kid Bike Calculator & Finder 🚲
Quickly find the best bike for your child based on their inseam.
Getting the right bike size is the single most important factor in whether your child enjoys riding and age is a surprisingly unreliable guide. Our kids bike size calculator uses your child’s inseam measurement instead, which is far more accurate. It then matches that measurement to every highly rated kids bike in our database, filtered by experience level, wheel size, and budget. No more guessing. Just enter the inseam and the right bikes come to you.
STEP 1: Measure your child’s inseam.
How to Measure Your Child’s Inseam in 60 seconds
You need: a book, a pencil, and a wall. Have your child stand barefoot with their back straight against the wall. Slide the book up between their legs snugly (as if it were a bike seat) and mark where the top of the book meets the wall. Measure from the floor to that mark in inches. That’s their inseam. Watch the video below for a visual walkthrough.
STEP 2: Click “Enable Kids Bike Sizes Tool”
STEP 3: Move slider to match your child’s inseam.
STEP 4: Select your child’s experience level.
STEP 5: Click on any desired wheel sizes, type or price and how you want the results sorted.
STEP 6: Unclick “Enable Kids Bike Sizes Tool” to scroll through all bike size options.
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 “first-time rider.”
The calculator only includes bikes we’ve personally tested and reviewed. If a bike isn’t in our database yet, it won’t appear.
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.