What this calculator does
Bike frame size works out recommended frame size from inseam length, by bike type. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaRoad size = inseam × 0.67; Trekking size = inseam × 0.64; MTB size = road size − 11 cm
The inputs explained
| Field | What to enter |
|---|---|
| Inseam length (cm) | A number, measured in cm. Starts at 80. |
| Bike type | Choose from Road, Mountain, Trekking / city. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with inseam length
Every other input is held at the calculator’s starting values while inseam length varies. Select any row to load that scenario into the calculator.