Auto
RPM to Speed Calculator
Vehicle speed at a given engine RPM using transmission and final-drive ratios plus tire diameter.
Inputs
RPM to Speed Calculator
Result
Speed
62.2 mph
- Speed
- 100.1 km/h
- RPM for 100 km/h
- 2,996
How it's calculated
mph = (RPM × 60 × π × tire_in) / (gear × final × 63360)
Common questions
What if I don't know my final drive ratio?
It's usually printed on the differential tag or listed in the owner's manual. Common values are 3.08, 3.42, 3.73, and 4.10 for RWD vehicles.
Why does tire diameter matter?
Bigger tires cover more distance per revolution, so at the same RPM the car goes faster (and the speedometer reads lower than actual).
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