Differential Gear Ratio Calculator

Enter Potential Maximum Safe Engine RPM  
Enter Tire Size Diameter  
Enter Desired Target MPH  
Rear End Gear Ratio Needed   :1
Enter the maximum potential safe engine RPM. Enter the tire size diameter and the target vehicle speed in MPH. Click on Calculate Differential Gear Ratio. The value will be returned in estimated differential gear ratio, based on the entered values. To do another, click the Clear Values button and then enter a new set of values.
Calculated accuracy of most browsers is generally 16 places.
Calculator below to convert from MPH to Klms/hour.

Convert from: to:

Although I have tried to make this as accurate as possible, I provide no warrantee of any kind. Please verify the results before you do anything important with the numbers. Rounding errors may occur because of the floating-point calculations used internally.