RPM Calculator
Enter any three values (RPM, ratio, tire diameter, speed) and the calculator will solve the rest.
Inputs
π§
Engine RPM
β
Unit fixed to rpm.
βοΈ
Transmission ratio
β
No unit (dimensionless).
π
Wheel RPM
β
Unit fixed to rpm.
β
Tire diameter
β
Tip: 185/55R15 β β 23 in overall diameter.
π
Vehicle speed
β
mph β km/h β m/s β ft/s conversions supported.
Quick summary
Auto-updates as you type. Enter any three fields to solve the rest.
References & constants
| Item | Value |
|---|---|
| Ο (pi) | 3.141592653589793 |
| Inches in a mile | 63,360 in |
| 1 mph | 1.609344 km/h = 0.44704 m/s = 1.4666667 ft/s |
| Inch conversions | 1 in = 25.4 mm = 2.54 cm = 0.0254 m = 1/12 ft |
| Core relations | RPMβ = RPMα΅₯ Γ Ratio; Speed = RPMα΅₯ Γ D Γ Ο Γ 60 / 63,360 |