What Size Bike Does My Child Need? (Free Kids Bike Size Calculator)
Buying the right size is the single biggest factor in whether your child actually rides. Too big "to grow into" makes starting and balancing scary; too small gets outgrown fast. Use the calculator below — enter your child's age, height, or (best of all) inside-leg measurement — for the right wheel size and the closest Gear Force bike.
Kids Bike Size Calculator
Find the right wheel size by your child's measurements — inseam (inside leg) is the most accurate, so use it if you can.
Free tool by Gear Force — kids' bikes, balance bikes & ride-ons, Australia-wide.
Kids bike size chart (by age, height & wheel size)
| Wheel | Age | Height | Inside leg |
|---|---|---|---|
| 12" (balance) | 2–4 | 85–100 cm | 30–42 cm |
| 14" | 3–5 | 95–110 cm | 40–50 cm |
| 16" | 4–6 | 105–120 cm | 45–55 cm |
| 18" | 5–7 | 115–128 cm | 55–63 cm |
| 20" | 6–9 | 122–140 cm | 60–74 cm |
| 24" | 8–11 | 135–155 cm | 72–86 cm |
Age is a starting point — height and especially inside-leg give a better fit. When between sizes, size down for confidence.
How to measure inside leg
Stand your child barefoot against a wall, pop a book up between their legs (spine up, like a saddle) and measure from the top of the book to the floor in cm. That number is the best predictor of the right bike.
FAQ
What size bike for a 5 year old? Most suit a 16" bike, but check height/inside-leg — taller kids may already fit an 18–20".
Should I buy bigger to grow into? No — an oversized bike is harder to control. Buy to fit now.
Balance bike or pedal bike first? Under ~4, a balance bike teaches balance fastest. See our Balance Bike Readiness Checker.
Ready to pick the bike?
Shop all Kids Bikes →
Shop Balance Bikes (first riders) →
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<p>Powered by the <a href="https://gearforce.com.au/blogs/kids-bikes/kids-bike-size-calculator">Kids Bike Size Calculator</a> from <a href="https://gearforce.com.au/">Gear Force</a>.</p>More free Gear Force tools
More from Gear Force: explore all our kids bike & ride-on buying guides and free tools.
At Gear Force, we’re all about helping Aussie families create fun, functional, and inspiring spaces — from playtime adventures to everyday living. We started with ride-on toys, bikes, and gear for kids, and we’re continuing to grow into new categories that bring joy, comfort, and practicality to family life.
Whether it's a toddler’s first balance bike or stylish, kid-friendly furniture, our team carefully curates every product to meet the highest standards of safety, quality, and value.
