Bike Size Calculator
An approximate frame size range for road, mountain and hybrid bikes from your height and inseam
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Gives an approximate frame size range for road, mountain and hybrid bikes from your height, using named public size charts, plus an estimate from your inseam and a starting saddle height. For children it lists the wheel sizes that kids' charts name for their height.
How to use
- Choose the "Bike type" and the unit.
- Enter "Your height"; the frame size range from the height charts appears at once.
- Optionally enter your "Inseam (inside leg)", measured as shown under "How to measure your inseam", for a rule-of-thumb frame size and a saddle height.
- Check the "Rows from the size charts" table to see which chart row each number comes from.
How it works
- The ranges come from the Wheelbase and BikeTips charts (kids: Schwinn and Wheelbase), read in October 2026 and listed under "Sources".
- Rules of thumb: road frame ≈ inseam × 0.665 cm, hybrid ≈ inseam × 0.685 cm, mountain ≈ inseam (cm) × 0.226 inches; saddle height ≈ inseam × 0.883.
- Makers measure frames differently, so the chart of the model you want and a test ride come first. This is not medical or bike-fitting advice.
Questions and answers
- What size road bike do I need at 172 cm?
- The charts used here suggest a 54 to 56 cm frame, size M. Check the chart of the model you are looking at.
- How do I measure my inseam?
- Stand barefoot against a wall, pull a book up between your legs like a saddle and measure from the floor to its top edge.
- How high should my saddle be?
- A common starting point is inseam × 0.883, measured from the centre of the crank axle to the top of the saddle. An 80 cm inseam gives about 70.6 cm.
- What wheel size for a 6-year-old?
- Height decides more than age. A child of about 110 cm usually fits a 16-inch wheel; the charts also list 14 or 18 inches near the edges of that range.