ratio / %
Pulley Ratio Calculator
Calculate speed ratio between driver and driven pulleys.
Mechanical engineering safety note
Mechanical engineering calculators on ToolsBing are preliminary educational and planning tools only. Verify material properties, machine specifications, safety factors, operating conditions, standards, and design assumptions with qualified engineers, manufacturer data, and applicable codes before design, procurement, or operation.
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Estimated result
Use for conceptual sizing, comparison, and learning only.
Check material ratings, machine data, service factor, standards, and safety requirements.
Formula and assumptions
Speed ratio = driver diameter ÷ driven diameter
This calculator uses simplified engineering assumptions. Real systems may require safety factors, manufacturer curves, fluid properties, thermal limits, fatigue checks, tolerances, and professional review.