gear ratio

Gear Ratio Calculator

Need to calculate gear ratios quickly and accurately? Our free Gear Ratio Calculator helps you work out gear ratio, final drive ratio, wheel RPM and estimated road speed.

Whether you are checking:

• drive gear and driven gear ratios
• final drive ratio calculations
• RPM to road speed
• tyre diameter and gearing changes

This simple online tool makes gear ratio calculations fast and easy.

How to Calculate Gear Ratio

Gear ratio is calculated by dividing the driven gear teeth by the drive gear teeth.

Formula:

Driven Gear Teeth ÷ Drive Gear Teeth = Gear Ratio

Gear Ratio Example

If the drive gear has 20 teeth and the driven gear has 40 teeth:

40 ÷ 20 = 2.00

So, the gear ratio is 2.00:1.

What Is Gear Ratio?

Gear ratio describes the relationship between two gears. It affects acceleration, torque multiplication, engine RPM and vehicle speed.

What Is Final Drive Ratio?

Final drive ratio is the additional gearing in the differential or drivetrain. The overall ratio is calculated by multiplying the gear ratio by the final drive ratio.

Common Gear Ratio Examples

• 20 drive teeth and 40 driven teeth = 2.00:1
• 18 drive teeth and 36 driven teeth = 2.00:1
• 15 drive teeth and 45 driven teeth = 3.00:1
• 22 drive teeth and 44 driven teeth = 2.00:1

Why Use Our Gear Ratio Calculator?

• Calculate gear ratios instantly
• Work out overall ratio with final drive
• Estimate road speed from RPM and tyre diameter
• Useful for cars, bikes, gearboxes and drivetrain setups
• No manual calculations needed