Compare cruising gears quickly
A speed-per-1,000-RPM view can make it easier to compare overdrive ratios without picking one road speed first.
Auto Tools
MPH per 1000 RPM Calculator
Estimate road speed for each 1,000 RPM from transmission ratio, rear gear ratio, and tire diameter.
Why this page exists
Driveline planning gets easier when gearing and tire size are turned into one speed-per-1,000-RPM number instead of being estimated mentally. This calculator helps visitors estimate miles per hour per 1,000 RPM from transmission ratio, rear gear ratio, and tire diameter.
Interactive tool
Run the estimate
Enter your numbers and read the result first, then use the sections below to understand what affects the outcome.
Calculator
MPH per 1000 RPM calculator
Estimate road speed for each 1,000 RPM from transmission ratio, rear gear ratio, and tire diameter.
Result
22.34 mph
Estimated miles per hour per 1,000 RPM based on gearing and tire diameter.
Miles per hour per 1,000 RPM22.34 mph
Equivalent km/h per 1,000 RPM35.95 km/h
Overall ratio used1.00 x 3.73 = 3.730
Tire diameter used28.00 in
- 28.00 in of tire diameter with a 1.00 transmission ratio and 3.73 rear gear works out to about 22.34 mph for every 1,000 RPM.
- That same gearing works out to about 35.95 km/h per 1,000 RPM on the same theoretical basis.
- Use the result as a planning estimate only, because converter slip, tire growth, tire deflection, and load can all change real road speed.
This is a driveline-speed estimate only. Converter slip, tire growth, tire deflection, and real-world load can all change actual speed per 1,000 RPM.
Planning note
Last updated April 16, 2026. Use this tool to compare scenarios and plan ahead, then confirm important details with the lender, employer, insurer, contractor, or other qualified provider involved in the final decision.
How it works
What the calculator is doing
Enter transmission gear ratio, rear gear ratio, and tire diameter.
The calculator combines the ratios into one overall gearing value.
It estimates how many miles per hour the setup produces for each 1,000 RPM.
Understanding your result
This is a practical driveline-speed estimate. Converter slip, tire growth, tire deflection, and real-world load can all move the actual result.
Browse more auto toolsExamples
Ways people use this tool
Example scenarios help turn a quick estimate into a more useful comparison or planning step.
See what a gear swap changes
Changing the rear gear ratio shows how quickly the speed-per-1,000-RPM number moves.
Check tire-size effects
A taller tire generally raises speed per 1,000 RPM, which can help with highway planning.
FAQ
Common questions
How is MPH per 1,000 RPM estimated here?
The calculator uses transmission ratio, rear gear ratio, and tire diameter to estimate theoretical road speed for every 1,000 RPM.
Why does tire diameter matter so much?
Because a larger tire travels farther per revolution, which raises the road speed reached at the same engine RPM.
Will this match real road speed exactly?
No. Converter slip, tire growth, and real-world load can shift actual speed away from a clean theoretical value.
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