Gear Ratio & Speed Calculator
Single stage, multi-stage, and planetary gear train analysis
Driver Teeth (z₁)
teeth
Driven Teeth (z₂)
teeth
Input Speed (n₁)
RPM
Input Power — optional
kW
Stage Efficiency
%
Single Stage Formulas
Gear Ratioi = z₂ / z₁
Output Speedn₂ = n₁ / i
Output TorqueT₂ = T₁ × i × η
Output PowerP₂ = P₁ × η / 100
Gear Ratio
Gear Ratio (i)
—
reduction
Output Speed
—
RPM
Input Torque
—
N·m (at given kW)
Output Torque
—
N·m
Output Power
—
kW
Power Loss
—
kW
Spur gear pair efficiency: typically 98.5–99% per stage.
Helical: 98–99%. Bevel: 97–99%. Worm: 50–90% depending on lead angle.