The indicated power of an IC engine (briefly written as I.P.) is the power actually developed by the engine cylinder. Mathematically,

 where

K = Number of cylinders,

pm = Actual mean effective pressure in bar (1 bar = 100 kN/m2),

L = Length of stroke in meters,

A = Area of the piston in m2,

n = Number of working strokes per minute

  = Speed of the engine for two stroke cycle engine

  = Half the speed of the engine for four stroke cycle engine.

Note : The I.P. of a multi-cylinder of spark ignition engine is determined by Morse test.