ClueLuma

Power versus speed calculator

Under affinity-law conditions, centrifugal shaft power varies with speed cubed.

Units
HP2=HP1×(N2N1)3\mathrm{HP}_{2} = \mathrm{HP}_{1} \times \left(\frac{N_{2}}{N_{1}}\right)^{3}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

HP
rpm
rpm
HP

Worked example

Given

  • HP1\mathrm{HP}_{1} = 40 HP
  • N2N_{2} = 1,400 rpm
  • N1N_{1} = 1,750 rpm
HP2=40×(14001750)3=20.48\mathrm{HP}_{2} = 40 \times \left(\frac{1400}{1750}\right)^{3} = 20.48

Symbols and units

SymbolMeaningUnit
HP2\mathrm{HP}_{2}new shaft powerHP
HP1\mathrm{HP}_{1}initial shaft powerHP
N2N_{2}new speedrpm
N1N_{1}initial speedrpm

Related calculators

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.