Calculate Top Speed by RPM

Enter Maximum Safe Engine RPM
Enter Tire Size Diameter
Enter Differential Gear Ratio :1
Enter Transmission Gear Ratio :1
Potential Calculated Vehicle Speed

Enter the maximum safe engine RPM. Enter the tire size diameter. Enter the differential gear ratio and the transmission gear ratio. Click on Calculate Potential Speed. The value will be returned in both miles per hour and kilometers per hour.

Table of contents:

How do you calculate speed from RPM?

Multiply the circumference by the object's angular speed, measured in rpm. For example, if it rotates at 400 rpm: 87.98 × 400 = 35,192. This is the object's surface speed, measured in inches per minute.

How do you calculate speed with rpm and gear ratio?

Engine RPM divided by total gear ratio, multiplied by the tire diameter and converted for units of measurement, gives vehicle's speed of travel.