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Gear Ratio Calculator

Calculate gear ratio and driven-shaft speed from tooth counts.

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Interactive calculation

Enter your values

Calculated result

This is a general planning estimate. Check units and verify critical results independently.

Why this result needs checking

Engineering results depend on inputs, assumptions and real-world conditions. Use this as a planning/checking value and verify critical work against manufacturer data, drawings or applicable standards. How our calculations work →

How to use it

Use consistent units and realistic inputs.

Calculate gear ratio and driven-shaft speed from tooth counts. Enter the requested values, calculate the result, then compare it with drawings, catalogues, standards or manufacturer information relevant to the job.

Common mistakes

  • Reversing driver and driven gears
  • Ignoring intermediate idler direction changes
  • Assuming speed ratio alone determines torque capacity

Frequently asked questions

What does this calculator calculate?

Calculate gear ratio and driven-shaft speed from tooth counts.

Is the answer exact?

No. The formula provides an engineering estimate based on the inputs and assumptions shown. Real systems can include tolerances, friction, losses, material variation and regulatory requirements.

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