Bike Frame Size Calculator

Work out bike frame size instantly with clear inputs, formula shown and shareable results.

About Bike Frame Size Calculator

Frame size is derived from inside leg, not height, because leg-to-torso proportions vary widely. The standard multipliers are 0.665 of inseam for road, 0.635 for hybrid and 0.57 for mountain bikes, and saddle height is 0.883 of inseam measured to the pedal spindle.

Formula

Frame sizing

frame size = inseam x type factor; saddle height = inseam x 0.883 (LeMond method)

Worked example

With the default values below, Bike Frame Size Calculator returns Recommended frame size of 55.86. Change any input above and every figure here is recalculated in your browser.

Inputs used

Rider height: 178 cm
Inside leg measurement: 84 cm
Bike typeone of Road, Mountain, Hybrid / city: Road

Results

Recommended frame size: 55.86 cm
Saddle height from bottom bracket: 74.17 cm
Minimum standover clearance: 81.50 cm
Size label: Large

Step by step

1Values used
2Frame sizing
3Recommended frame size= 55.86 cm
4Saddle height from bottom bracket= 74.17 cm
5Minimum standover clearance= 81.50 cm
6Size label= Large

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why use inseam rather than height?

Two riders of the same height can differ 8 cm in leg length. The saddle-to-pedal relationship depends on leg length alone.

Where does 0.883 come from?

The LeMond formula, a long-standing fitting heuristic. It gives a starting point; final saddle height is set by knee angle observation.