Gear Ratio Calculator

Calculate total gear ratio, output speed, output torque, active stages, and direction change for single-stage or multi-stage external gear trains.

Open Calculator Gearbox Output Torque
Good starting use case: enter input speed, input torque, efficiency, and one or more gear stages to estimate total reduction, output shaft speed, torque multiplication, and direction reversal before final mechanical selection.
Calculator

Estimate Gear Train Ratio and Output

This calculator is useful for machine design, conveyors, automation systems, servo-driven mechanisms, and general power transmission estimates. It is intended for quick engineering calculations, not final validation.

It helps estimate total gear train ratio, speed reduction, output shaft speed, and torque multiplication for external gear sets. This is useful for reducer sizing, drive design, machine mechanisms, and automation engineering calculations.

Quick examples
General Inputs
Gear Stages
Enter values and click Calculate.

Need help applying this to a real machine?

Get connected with a qualified automation integrator if you are sizing a reducer, designing a transmission, or trying to match motor speed to mechanism speed in a real system.

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Assumes standard external gear meshes. Each external gear mesh reverses rotation direction. Output torque is estimated using entered efficiency. For compound trains, total ratio is the product of all active stage ratios.

Where this calculator helps

Gear ratio drives speed reduction and torque multiplication. This is useful for conveyors, servo axes, rotating tooling, fixtures, lift mechanisms, and any machine function where motor speed is too high for the driven load.

After estimating ratio, you usually still need to check gearbox torque limits, motor torque availability, inertia effects, and whether the selected transmission meets acceleration and duty requirements.

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What this calculator gives you

  • Total gear ratio
  • Output speed
  • Output torque estimate
  • Direction reversal result
  • Per-stage ratio breakdown

Common uses

This helps with reducer selection, mechanism layout, servo-to-load matching, conveyor transmission planning, and early machine concept work.

Things to verify next

  • Gearbox torque limits
  • Motor torque and acceleration margin
  • Duty cycle and heat
  • Backlash and positional accuracy
  • Shock load and service factor