Speed by Gear Calculator

Theoretical speed in every gear at a given RPM (e.g. redline) from gearbox ratios, final drive and tire size.

Formula

Speed = [Engine RPM / (Gear ratio × Final drive ratio)] × Circumference × 60 / 1 000 000

Assumptions

If no tire size is entered, a common size is used as a worked example.

How to read it

Speed per gear shows how the gearbox is spaced: even steps mean smooth shifts without a rev gap. Top-gear theoretical speed is only reached if power allows — real top speed depends on aerodynamics.

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Next tools

Mechanical & performanceRPM to Speed CalculatorFrom engine RPM, gear ratio, final drive and tire size, calculate theoretical road speed.Calculate →Mechanical & performanceFinal Drive Ratio CalculatorOverall ratio (gear × final drive) and road speed at a given RPM — compare final drives before you swap.Calculate →Tires & wheelsTire Size CalculatorEnter a tire size (e.g. 225/45R17) to get its diameter, circumference and revolutions per mile or km.Calculate →