The engine pressure ratio (EPR) is the total pressure ratio across a jet engine, measured as the ratio of the total pressure at the exit of the propelling nozzle divided by the total pressure at the entry to the compressor.[1]

Jet engines use either EPR or compressor/fan RPM as an indicator of thrust.[2] When EPR is used, the pressures are measured in front of the compressor and behind the turbine.

Integrated engine pressure ratio

The integrated engine pressure ratio (IEPR) is a ratio used on some turbofans to include fan discharge total pressure and compressor inlet total pressure. If compressor inlet pressure is P0 and fan discharge total pressure is P1 , then the integrated engine pressure ratio will be P1 /P0. [3]

The IEPR is an engine indicator system unique to the Rolls-Royce RB211.

See also


  1. ^ Glenn Research Center (NASA). "Pressure variation - EPR". Retrieved January 2, 2015.
  2. ^ "Engine Pressure Ratio (EPR)". Archived from the original on 2014-10-04.
  3. ^ "integrated engine pressure ratio". Retrieved 2023-06-07.