RPM to Linear Speed Calculator

Convert a wheel's RPM into how fast it travels.

How the Math Works

The RPM to Linear Speed Calculator uses the fundamental relationship between rotational and linear motion. When a wheel completes one full revolution, a point on its circumference travels a distance equal to the wheel's circumference, which is π multiplied by the diameter. Since RPM measures revolutions per minute, we multiply the circumference by RPM to find the distance traveled per minute. Finally, dividing by 60 converts this to distance per second, giving us the linear velocity in consistent units.

Practical Applications

To use this calculator practically, first measure or obtain the wheel's diameter in the same units you want for your speed result (inches, centimeters, or meters). Enter the wheel's RPM value from your vehicle's tachometer, bike computer, or motor specifications. For example, a bicycle wheel with 26-inch diameter spinning at 90 RPM produces a linear speed of approximately 12.2 feet per second (calculated as π × 26 × 90 ÷ 60 ÷ 12). This conversion is essential for automotive engineering, bicycle speedometers, and machinery diagnostics.

Day-to-Day Use

Understanding this relationship helps you make informed decisions about vehicle performance, maintenance, and safety. When shopping for tires, you can calculate how speedometer readings might change with different tire sizes. Cyclists can determine optimal gear ratios by understanding how cadence and gear ratios translate to actual road speed. DIY enthusiasts working on machinery, lawn equipment, or automotive projects can verify that components operate within safe speed limits, preventing costly failures and ensuring equipment longevity.

Worked example

500 RPM, 0.6 m wheel → 15.7 m/s (56.5 km/h).

FAQ