Gear Ratio Calculator — Chainring to Sprocket Ratio
Calculate gear ratios from chainring and sprocket tooth counts.
How We Calculate This
Gear Ratio Formulas
- Gear Ratio = Chainring teeth ÷ Sprocket teeth
- Gear Inches = Gear Ratio × Wheel diameter (inches)
- Development (m) = Gear Ratio × Wheel circumference (m)
- Gain Ratio = (Wheel radius ÷ Crank length) × (Chainring ÷ Sprocket)
Gain ratio (Sheldon Brown) is dimensionless: it compares how far the bike travels to how far the pedal moves in its orbit, so unlike gear inches it accounts for crank length. Wheel radius and crank length must be in the same units (the calculator derives the radius from your wheel circumference ÷ 2π).
Frequently Asked Questions
Related Calculators
Gear Inches Calculator
Convert gear ratios to gear inches for comparison.
Development Calculator
Calculate distance travelled per pedal revolution for any gear.
Chainring Calculator
Compare chainring sizes and their effect on gearing range.
Cassette Calculator
Analyse cassette tooth counts and gear jumps between sprockets.
Speed in Gear Calculator
Calculate road speed for any gear at a given cadence.
Last updated: 2025-02-20
All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.