Engine rpm calculator

Find engine rpm = road speed ÷ tire circumference × gearbox ratio × final drive.

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Road speed (m/min)

Rolling tire circumference (m)

More inputs and assumptions

Gear ratio

Final drive ratio

Answer

…

Find engine rpm = road speed ÷ tire circumference × gearbox ratio × final drive.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Step-by-step calculation

Inputs are substituted below. Each line evaluates the next operation; intermediate values are displayed to 12 significant digits while the calculation uses full precision.

Saved scenario

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Formula and assumptions

Road speed is metres per minute, circumference metres. Assumes no tire slip, clutch slip or torque-converter slip. Use measured rolling circumference for better geometry.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Engine rpm calculator

Find engine rpm = road speed ÷ tire circumference × gearbox ratio × final drive.

Road speed is metres per minute, circumference metres. Assumes no tire slip, clutch slip or torque-converter slip. Use measured rolling circumference for better geometry.

Next: Gear ratio calculator

A worked example

Example inputs: road speed (m/min) = 1000, rolling tire circumference (m) = 2, gear ratio = 1, final drive ratio = 4. Engine speed (rpm) = 2000.

Before you use the result

Road speed is metres per minute, circumference metres. Assumes no tire slip, clutch slip or torque-converter slip. Use measured rolling circumference for better geometry.

Example results for road speed (m/min)

These examples use Rolling tire circumference (m): 2; Gear ratio: 1; Final drive ratio: 4. They are reference calculations, not recommended settings.

Road speed (m/min)	Engine speed (rpm)
500	1000
1000	2000
2000	4000

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