Gear Ratio, Speed & Engine RPM Calculator
Calculate road speed (MPH & km/h) or engine RPM from transmission gear ratios, differential axle ratio, and tire diameter for manual, automatic, and racing drivetrains.
Drivetrain & Tire Parameters
RPM
MPH
:1
E.g., 3.08, 3.42, 3.73, 4.10, 4.56.
Inches
Outer rolling diameter.
Calculated Road Speed
TOTAL RATIO: 3.73:1
67.0 MPH
Equivalent metric speed: 107.8 km/h
Overall Gear Reduction
3.73:1
Trans ratio × Axle ratio
Tire Rolling Revs
720 Rev/mi
88.0 in circumference
Drivetrain Summary Table
Gear
Ratio
Speed @ RPM