Calculate Gear Ratio and Output RPM

A free browser-based gear ratio calculator for robotics, RC vehicles, and mechanical designs. Add up to 6 gear stages, enter input RPM and torque, and instantly see the total ratio, output speed, and torque gain across the entire drivetrain.

How to Use the Gear Ratio Calculator

1
Enter drive parameters

Type the input RPM. Optionally add input torque (N·m) and drivetrain efficiency (%) to calculate output torque.

2
Add gear stages

Each stage has a driving gear (teeth) and a driven gear (teeth). Click "Add Stage" for multi-stage trains. Up to 6 stages supported.

3
Read the results

The total gear ratio, output RPM and torque are calculated instantly. A badge shows whether the train is a reduction, overdrive, or 1:1.

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Compute output RPM and torque for any multi-stage gear train instantly

Drive Parameters
RPM
N·m
%
Gear Stages
Quick Presets
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Features

Multi-stage gear trains — up to 6 stages in series Calculates total ratio, output RPM and output torque in real time Drivetrain efficiency input to account for friction losses Identifies reduction vs overdrive and mechanical advantage Per-stage ratio breakdown and 3 quick presets Results saved automatically — restored on next visit

FAQ

How is gear ratio calculated?

For a single stage: ratio = driven teeth ÷ driving teeth. For multiple stages: multiply all stage ratios together. A ratio > 1 means reduction (slower output, more torque); < 1 means overdrive (faster output, less torque).

How is output RPM calculated?

Output RPM = Input RPM ÷ Total Gear Ratio. For example, 1000 RPM through a 4:1 reduction gives 250 RPM output.

What does mechanical advantage mean?

Mechanical advantage equals the total gear ratio. A 5:1 reduction multiplies torque by 5 (before efficiency losses), letting a small motor move heavy loads.

Why include drivetrain efficiency?

Every gear mesh loses a little energy to friction — typically 1–5% per stage. Enter a value below 100% to get a realistic output torque after losses.

What is overdrive?

An overdrive gear train (ratio < 1) increases output speed at the cost of torque. Common in bicycle cassettes and car transmission top gears.

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Who is this tool for?
🔌 Electronics Enthusiasts 🤖 Robotics
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