Gear Ratio Calculator

Calculate gear ratios, speed ratios, torque multiplication, and gear specifications.

Or enter diameter/radius (use same units for both)
Or enter diameter/radius (use same units for both)
Current Formula:

Gear Ratio = Driven Teeth / Driver Teeth

Also equals: Output Speed / Input Speed = Input Torque / Output Torque
Gear Ratio Guide:
  • Speed Reduction (GR > 1):
  • • Decreases output speed
  • • Increases output torque
  • • Example: 3:1 = 3x torque, 1/3 speed
  • Speed Increase (GR < 1):
  • • Increases output speed
  • • Decreases output torque
  • • Example: 0.5:1 = 1/2 torque, 2x speed

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