Vehicle Speed Gear Ratio Calculator

This calculator helps you determine the speed of a vehicle based on the gear ratio, engine RPM, and tire radius.

Input Parameters

Calculation Results

Vehicle Speed

0 mph

Calculation Formula

Speed (mph) = (Engine RPM * Gear Ratio * π * Tire Diameter (inches)) / (63,360)

Where:
π (pi) ≈ 3.14159
63,360 = number of inches in a mile

Vehicle Speed Gear Ratio Calculator Usage Guide

Learn how to use the Vehicle Speed Gear Ratio Calculator and its working principles

How to Use the Calculator

  1. Enter the Engine RPM in the first input field.
  2. Enter the Gear Ratio in the second input field.
  3. Enter the Tire Diameter in inches in the third input field.
  4. Click the "Calculate" button to compute the vehicle speed in miles per hour (mph).
  5. Click the "Reset" button to clear all input fields and results.

Understanding the Formula

The calculator uses the following formula to determine the vehicle speed:

Speed (mph) = (Engine RPM * Gear Ratio * π * Tire Diameter (inches)) / 63360

Where:

  • Engine RPM is the revolutions per minute of the engine.
  • Gear Ratio is the ratio of the number of teeth on the driven gear to the number of teeth on the driving gear.
  • Tire Diameter (inches) is the diameter of the tire in inches.
  • π (pi) is a mathematical constant approximately equal to 3.14159.
  • 63360 is the number of inches in a mile (5280 feet/mile * 12 inches/foot).

Example

If an engine is running at 3000 RPM, the gear ratio is 3.5, and the tire diameter is 30 inches, the vehicle speed would be calculated as follows:

Speed = (3000 * 3.5 * 3.14159 * 30) / 63360 ≈ 45.24 mph