AIEngineeringTool

Gear Ratio Calculator

Calculate the ratio and output speed for a simple external gear pair.

Driver gear teeth: 20 teeth
Live concept view — geometry scales with the entered design condition.

Calculate the ratio and output speed for a simple external gear pair.

Design inputs

Enter known values using the units shown. Results and the live SVG view update immediately.

PRELIMINARY RESULT

Gear ratio3.000 : 1

Driven speed: 480.00 RPM

Gear ratio
3.000 : 1
Driven speed
480.00 RPM

Calculation detail

Formula: i = Z₂ / Z₁; N₂ = N₁ / i

The output speed is obtained from the tooth-count ratio for an ideal simple gear pair.

FORMULA VERIFICATION

Units, scope and reference

Reference: ISO 21771 reference terminology; ideal gear-ratio relation N₁Z₁ = N₂Z₂.

Internal unit basis: tooth count and rpm. Outputs: ratio, rpm.

Valid conditions: Positive whole-number tooth counts; positive rpm.

Limitations: Ideal kinematics only; no strength, contact ratio or losses.