Gear Ratio Converter

Reviewed by the CalculatorHub team, edited by James Graham. Method from CalculatorHub methodology. Last verified 2026-06-23.

The Gear Ratio Converter computes gear ratio from the relation gear ratio = driven gear teeth / drive gear teeth. It takes 2 inputs (driven gear teeth count in teeth, drive gear teeth count in teeth) and returns the gear ratio. These tools cover a mixed set of everyday calculations that do not belong to one subject heading: a physical quantity such as density, work done or power, components combined in series, a drive ratio, or a chance-based draw. They suit students and hobbyists, people building or repairing something at home, and anyone who wants a single number quickly without building a spreadsheet. Enter your values below and the result updates instantly, and you can share a permalink that pre-fills the exact calculation. Each result follows directly from the figures you type in, so confirm what every field is asking for, including its unit where one applies, before you read anything into the answer. For the chance-based tools, set the range and the number of values first, then take the run as it comes, because each run is independent of the one before it. For example, with driven gear teeth count = 36 teeth, drive gear teeth count = 12 teeth, the gear ratio works out to 3, and the worked example further down the page shows every step so you can follow the arithmetic and reproduce it by hand. The method is the standard form documented by CalculatorHub methodology, and the figure above each result carries the date it was last verified. Being a mixed group rather than one discipline, this set has no single limitation: the physical and electrical results are arithmetic on the values you supply and assume the clean, idealised arrangement the formula describes, so a real material, component or drivetrain can behave differently in use, while the chance-based results are ordinary computer-generated randomness, fine for a game or an informal draw but not for security keys, wagering, or anything that has to be provably fair.