Use the Gear Ratio calculator to estimate gear ratio from driven gear, driving gear. Motorsport Math shows the formula and updates the result instantly.
Ideal theoretical result. Validate against manufacturer data, component limits and your race-series regulations before safety-critical use.
The Gear Ratio Calculator converts driven gear and driving gear into gear ratio. It is designed for quick motorsport planning when you need the calculation visible, repeatable, and easy to adjust rather than hidden inside a spreadsheet cell. Drivetrain calculations are useful for gear selection, final-drive comparison, shift planning, top-speed checks, and rotating component limits.
For example, with driven gear set to 36 teeth and driving gear set to 15 teeth, the calculator returns 2.4 :1 for gear ratio. Change one input at a time if you want to understand which value is driving the result.
Gear ratio is shown in :1. Use the number as a calculated reference point, then compare it with measured data from the car, the part supplier, or the race environment. A mathematically clean answer can still be unsuitable if the inputs are estimated, rounded, measured under different conditions, or outside the normal range for the vehicle.
It is used to estimate gear ratio from driven gear and driving gear. The page is most useful when you want a fast result, visible assumptions, and a repeatable way to compare motorsport setup options.
The arithmetic follows the formula shown on the page, but the practical accuracy depends on the inputs. Measurements, environmental conditions, component tolerances, and race regulations can all affect whether the result is suitable for real use.
Use it as an engineering reference, not as the final authority. Safety-critical decisions should be checked against manufacturer data, professional engineering judgement, inspection, testing, and the rules for the series or event.