Gear Ratio Calculator

• Free online gear ratio calculator with three calculation modes: single-stage gear ratio, input/output RPM, and compound gear train
• Each gear ratio result is automatically labelled by drive type (reduction / direct / increase), and the RPM mode also shows output speed and the torque multiplication factor
• A reference card lists common gear ratios (1:1, 2:1, 3:1, 4:1, 5:1 and more); click one to auto-fill the matching teeth counts
• All calculations run locally in your browser — nothing is uploaded

1. Open the tool page — no download or installation needed
2. Switch to the mode you need at the top: single-stage gear ratio, RPM calculation, or compound gear train
3. Enter the drive and driven teeth counts (also the input RPM in RPM mode); results are computed and shown live as you type
4. Review the gear ratio, drive type, output RPM or total ratio, and click "Copy" to grab a value with one click if needed

• This tool is completely free and requires no sign-up
• Everything runs locally in your browser — nothing is uploaded
• Teeth counts must be positive integers (not zero), and the compound mode supports 1 to 6 gear stages

Free online gear ratio calculator supporting single-stage gear ratio calculation, input/output RPM calculation, compound gear train ratio calculation, teeth ratio calculation, and more. Ideal for mechanical design, gear transmission system design, reducer design, and industrial drive applications.

Open the tool page — no download or installation needed Switch to the mode you need at the top: single-stage gear ratio, RPM calculation, or compound gear train Enter the drive and driven teeth counts (also the input RPM in RPM mode); results are computed and shown live as you type Review the gear ratio, drive type, output RPM or total ratio, and click "Copy" to grab a value with one click if needed

This tool is completely free and requires no sign-up Everything runs locally in your browser — nothing is uploaded Teeth counts must be positive integers (not zero), and the compound mode supports 1 to 6 gear stages

Yes, Gear Ratio Calculator is completely free. No download or installation required — it runs right in your browser.