RPM to Speed Calculator

From engine RPM, gear ratio, final drive and tire size, calculate theoretical road speed.

Formula

Speed = [Engine RPM / (Gear ratio × Final drive ratio)] × Circumference × 60 / 1 000 000

Assumptions

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

How to read it

Theoretical speed ignores slip and tire squash. Use it to compare gearbox or final-drive ratios, or to estimate engine revs at a given cruising speed.

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