Mechanical calculator

Gear Ratio Calculator

Find speed and torque relationships from driver and driven teeth.

Use calculator View formulas FAQ

Calculator

Enter mechanical values

Select units beside each input. Results update automatically.

Mechanical

Driver gear teeth
Driven gear teeth
Input speed rpm
Input torque Nm
Efficiency %

Result

About this calculator

How it works

Gear ratio compares driven gear teeth to driver gear teeth. Speed is reduced and torque is increased when the driven gear has more teeth.

Formulas

Formulas used

Gear ratio

GR = driven teeth / driver teeth

Output speed

n2 = n1 / GR

Output torque

T2 = T1 x GR x efficiency

Worked example

Example calculation

Gear ratio

20 driving 60 teeth gives GR = 3:1

Output speed

1800 rpm / 3 = 600 rpm

Guide

How to use this calculator

Enter the known machine, motion, power, or geometry values.
Select units beside inputs where unit menus are shown.
Use the highlighted result first, then review supporting values for design context.

Reference

What the results mean

Gear ratio

Speed reduction or multiplication between driver and driven gears.

Output torque

Estimated torque after ratio and efficiency.

Assumptions and limits

Before using the result

Calculations are simplified engineering estimates for idealized geometry and operating conditions.
Real systems may require efficiency, fatigue, slip, vibration, lubrication, thermal, tolerance, and manufacturer data checks.
Use applicable standards, safety factors, test data, and qualified engineering judgement for final machine design.

FAQ

Gear Ratio Calculator questions

Can I use different units?

Yes. Select the unit beside each input. The calculator converts values internally before solving.

Are these results suitable for final machine design?

Use the results for education, screening, and early design checks. Final designs should include verified data, safety factors, standards, fatigue, tolerances, and manufacturer guidance.

Why can real mechanical systems differ from the result?

Real systems include friction, slip, wear, vibration, misalignment, efficiency losses, and manufacturing variation.