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Coupling Torque Calculator

Work out coupling torque instantly with clear inputs, formula shown and shareable results.

About Coupling Torque Calculator

Nominal torque in newton metres is 9550 times kilowatts divided by rpm. A coupling is then selected on design torque, nominal torque multiplied by a service factor that reflects load character: around 1.2 for smooth centrifugal loads and 2.0 or more for reciprocating machines. Peak capability should be roughly twice the design value to survive start-up.

Formulas

Nominal torque

T N·m = 9550 x kW / rpm

Design torque

T design = T nominal x service factor

Worked example

With the default values below, Coupling Torque Calculator returns Coupling design torque of 148.2. Change any input above and every figure here is recalculated in your browser.

Inputs used

Transmitted powerminimum 0.1 kW
15 kW
Shaft speedminimum 1 rpm
1,450 rpm
Service factorminimum 1
1.5

Results

Coupling design torque
148.2 N·m
Nominal torque
98.8 N·m
Design torque in imperial units
109.3 lb·ft
Peak torque capability needed
296.4 N·m

Step by step

  1. 1Values used
  2. 2Nominal torque
  3. 3Design torque
  4. 4Coupling design torque= 148.2 N·m
  5. 5Nominal torque= 98.8 N·m
  6. 6Design torque in imperial units= 109.3 lb·ft
  7. 7Peak torque capability needed= 296.4 N·m

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Coupling Torque figure worked out?

T N·m = 9550 x kW / rpm. Nominal torque in newton metres is 9550 times kilowatts divided by rpm.

What does the service factor really cover?

Torque pulsation, starting inrush and the possibility of a locked rotor. It is not a safety factor on material strength but an allowance for load duty.

What values do I need to enter?

This calculator takes 3 inputs: Transmitted power, Shaft speed, Service factor. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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