Bike Gear Ratio Calculator

Compute gear ratios, gear inches, development, and speed-at-cadence for any chainring and sprocket combo. Runs locally in your browser.

Chainring teeth

front chainring tooth count

Sprocket teeth

rear sprocket tooth count

Wheel diameter (mm)

bead-seat diameter; 622 = 700c road

Tire width (mm)

outer tire width

Cadence (rpm)

pedal revolutions per minute

Enter values to compute gear metrics.

Gear ratio is chainring ÷ sprocket. Gear inches = diameter × ratio. Development (m) = π × wheel diameter × ratio ÷ 1000. Speed (km/h) = development × cadence × 60 ÷ 1000. Tire diameter is included: effective diameter = bead-seat + 2 × tire width. Runs locally — nothing leaves your browser.