Auto & Transport
Gear Ratio Calculator - Calculate speed vs RPM for different gear ratios
Calculate speed vs RPM for different gear ratios
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
Frequently asked questions
What is final drive ratio?
The gear ratio in the differential. Higher number = more torque multiplication, lower top speed.
Why calculate this?
Helps choose gearing for desired RPM at cruising speed, or planning transmission swaps.
Does tire size affect this?
Yes, larger tires effectively lower your gearing - higher speed per RPM but less acceleration.
Related tools
About this tool
Inputs
- Tire Diameter
- Final Drive Ratio
- Gear Ratios
- Target RPM
Results
- Speed at Target RPM
- RPM at 60 mph by Gear
- Overall Ratios
- RPM vs Speed Chart
You do not need a spreadsheet to calculate speed vs rpm for different gear ratios. This Gear Ratio Calculator gives you the answer in seconds. You supply tire diameter, final drive ratio, gear ratios and target rpm, and the tool calculates speed at target rpm, rpm at 60 mph by gear, overall ratios and rpm vs speed chart from those figures. Having a dedicated tool to calculate speed vs rpm for different gear ratios saves time you would otherwise spend searching for formulas or setting up a spreadsheet. Factor in insurance, registration, and depreciation when calculating the true cost of vehicle ownership.
Real-world driving conditions (temperature, terrain, driving style) always deviate from published specs. Yes, larger tires effectively lower your gearing - higher speed per RPM but less acceleration. Engine horsepower can be estimated from torque: HP = Torque × RPM ÷ 5252. Vehicle calculations help drivers plan costs, maintenance schedules, and performance expectations. Results are rounded for display; the underlying computation retains full precision.