Speed to RPM Calculator

Engine RPM at a given road speed from gear ratio, final drive and tire size — cruising revs at a glance.

Formula

RPM at this speed = Speed (km/h) × 1 000 000 / (60 × Circumference) × Gear ratio × Final drive ratio

Assumptions

If no tire size is entered, a common size is used as a worked example.

How to read it

Cruising revs drive noise, fuel use and wear. On the highway most modern cars sit between 2,000 and 3,000 rpm in top gear; a much higher figure suggests checking the gearbox, final drive or tire size.

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