Chain Drive Calculator

A chain drive transmits power from one shaft to another through sprockets linked by a chain, the system that drives bicycles, motorbikes, go-karts, conveyors and countless machines, and this calculator works out how it changes speed and torque. Enter the number of teeth on the driver sprocket, the number on the driven sprocket, and the driver's speed in revolutions per minute, and it returns the drive ratio, the output speed and the torque multiplication, updating as you type. The principle is the same as gears but with the two wheels separated and joined by a chain, so the teeth must match the chain pitch and the relationship is governed entirely by the tooth counts. The ratio is simply the driven teeth divided by the driver teeth. When the driven sprocket is larger, the output turns more slowly but with proportionally more torque, which is exactly what you want for climbing a hill or driving a heavy load; when it is smaller, the output spins faster with less torque, ideal for speed on the flat. Speed and torque trade off precisely in step with the ratio, so the power passing through stays much the same apart from friction losses, which is why changing sprockets is the standard way to tune a machine for either pulling power or top speed. Seeing the ratio, output speed and torque factor together makes that trade-off concrete and takes the guesswork out of choosing or swapping a sprocket. That makes the tool genuinely useful for mechanics, makers and engineers setting up bikes, karts, motorbikes and machinery, for students learning about ratios and power transmission and checking homework, and for anyone gearing a chain drive for the job. The formulas and a worked example are explained clearly below.

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