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DRIVETRAIN / CALCULATOR

Gear ratio &
speed calculator.

Calculate theoretical vehicle speed, overall gearing and RPM drop between shifts based on transmission ratios, final drive ratio, tire diameter and engine RPM.

01 /

Vehicle & drivetrain

For best accuracy, use the actual measured tire diameter.
rpm
%
Use 0% for a manual transmission or locked converter.
02 /

Transmission

Presets represent common gear sets. Verify the actual ratios used in your transmission.
03 /

Quick Change

How does the calculation work? + −

Vehicle speed is determined by engine RPM, transmission ratio, final drive ratio and tire rolling circumference.

Overall ratio = transmission ratio × final drive ratio × Quick Change ratio

Converter slip reduces actual vehicle speed relative to the theoretical mechanical speed. For example, 5% slip means the vehicle travels at approximately 95% of the theoretical speed at the same engine RPM.

RPM after a shift is calculated assuming vehicle speed remains effectively unchanged during the gear change.

RPM after shift = shift RPM × next gear ratio ÷ current gear ratio

Nominal tire size does not always match actual rolling diameter. For best accuracy, use the measured tire diameter or manufacturer rollout specification. Transmission preset ratios can also vary by model, year and internal gear set.

Ring and Pinion Gears
Ring and Pinion Gears
Quick Change Gears
Quick Change Gears