Bike Size Calculator

How to use this calculator

Enter your values. The result updates as you type; press Calculate to confirm and jump to the result on mobile. Use Share to send the calculator with your result.

Rules of thumb

These inseam multipliers are the long-standing fitting shortcuts used by bike shops. The saddle-height rule was popularized by Tour de France winner Greg LeMond and measures from the bottom bracket center to the saddle top.

How to measure inseam

1. Stand barefoot with your back to a wall, feet about 15–20 cm apart.
2. Pull a hardcover book up firmly between your legs, spine up, like a saddle.
3. Mark the wall at the top of the book and measure from the floor.

Between sizes?

Choose the smaller frame for a more agile, upright feel (and add a longer stem if needed), or the larger for a stretched-out, stable ride. Reach and stack, listed in brand geometry charts, describe fit better than seat-tube length alone.

Frequently asked questions

About this tool

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Last updated

31 Oct 2026

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