Gear ratio calculator

Tooth counts to ratio, output RPM, and torque multiplication — single stage or two-stage compound trains.

Driven ÷ drive teeth per stage — optionally a second stage and an input RPM.

Stage 1

Torque multiplier ignores efficiency — real gears lose a few % per stage.

Everything runs in this browser.

How to use

  1. Enter driver and driven tooth counts.
  2. Optionally add a second stage and input RPM.
  3. Read ratio, output speed, and torque factor.

What it supports

Spur-gear trains of 1 or 2 stages, teeth 1–500 per gear, input RPM up to 1e6. Ideal ratios only — efficiency losses are not modeled.

Related tools

Related guides