Gear Ratio Speed Calculator
Calculate vehicle speed for a given RPM and gear ratio.
Formula
Speed is calculated using the following formula:
MPH = (RPM × Tire Diameter) / (Gear Ratio × Axle Ratio × 336)
Where 336 is a constant derived from units conversion (inches to miles, minutes to hours).
Applications
Use this tool to determine your cruising RPM on the highway or your theoretical top speed in a specific gear.