Gear Ratio Calculator

 
Select Transmission :
Engine RPM : Enter your desired RPM for racing or cruising here.
Axle Ratio : Enter your rear axle ratio here.
Tire Height (in) : Enter your tire height here. Use the Aspect Ratio calculator below if you do not know your tire height.
  Ratio MPH  
1st Gear The estimated speed you will be traveling based on the parameters you established and the transmission you selected.
2nd Gear
3rd Gear  
4th Gear  
5th Gear  
6th Gear  

ASPECT RATIO CALCULATOR: Find your tire height using this calculator.

Enter the tire width in millimeters, the aspect ratio, the wheel diameter in inches, and Click on Calculate
Tire Width (mm) Wheel Diameter (in)
Aspect Ratio (1-100)
Tire Height (in) Tire Width (in)
 

Gear Calculator – Gear Ratio, Speed & Torque Estimator

The Gear Ratio Calculator helps you calculate the relationship between input and output gears. It’s useful in automotive tuning, cycling, robotics, and mechanical engineering for understanding how speed and torque are affected by different gear sizes.

How to Use the Gear Ratio Calculator

Enter:

  • Number of teeth on the input (driver) gear
  • Number of teeth on the output (driven) gear
  • Optional: input RPM (rotations per minute)

The tool will calculate the gear ratio, output RPM, and whether torque is increased or decreased.

Gear Ratio Formula

Gear Ratio = Teeth on Driven Gear ÷ Teeth on Driver Gear
Output RPM = Input RPM ÷ Gear Ratio
A ratio > 1 means torque increases and speed decreases. A ratio < 1 means speed increases and torque decreases.

Example

Driver Gear: 20 teeth
Driven Gear: 40 teeth
Input RPM: 1000
→ Gear Ratio = 40 ÷ 20 = 2
→ Output RPM = 1000 ÷ 2 = 500 RPM
→ Torque is doubled; speed is halved.

Common Use Cases

  • Automobile gear tuning (engine, transmission)
  • Cycle gear optimization
  • RC cars and robotics
  • Mechanical engineering and industrial machines
  • Physics and mechanical advantage calculation

Why Use a Gear Ratio Calculator?

Understanding gear ratios helps improve performance, efficiency, and mechanical balance. Whether you’re building a custom machine or tuning a vehicle, this tool simplifies the math.

Frequently Asked Questions (FAQs)

What is a good gear ratio for speed?

Lower gear ratios (<1) increase speed but reduce torque — ideal for racing or light loads.

What gear ratio gives more torque?

Higher ratios (>1) reduce speed but multiply torque — ideal for heavy-duty or climbing power.

Can this be used for bikes?

Yes, this calculator works perfectly for bike gear optimization and cadence control.

What units are used for RPM?

RPM stands for rotations per minute. Input and output RPM must be in the same unit.

Can I calculate reverse gear speed?

Yes, the same ratio formula applies — just account for directional change in gearing.