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Gear Ratio Calculator

Work out overall gear ratio, output speed and output torque for single or multi-stage gear trains.

Works in BrowserInstant
RPM
N·m
%
Driver TeethDriven TeethRatio
Overall Ratio
Output RPM
Output Torque
Output Power

💡 Ratio is driven ÷ driver teeth. A ratio above 1 is a reduction — slower output, more torque. Below 1 is an overdrive — faster output, less torque. Idler gears between the driver and driven gear change direction but not the ratio.