Mean Effective Pressure Calculator

Mean Effective Pressure Calculator: Size-Independent Engine Performance

Mean effective pressure is a theoretical constant pressure that, if it acted on the piston for the entire power stroke, would produce the same net work as the real combustion cycle. It lets engineers compare the performance of engines with very different displacements on equal footing.

The Formula

MEP = (Power × n_R) / (Displacement Volume × N)

Worked Example

A four-stroke engine (n_R = 2) with 2.0 L displacement produces 100 kW at 6,000 RPM.

MEP = (100,000 W × 2) / (0.002 m3 × 100 rev/s) = 1,000 kPa

How to Use This Calculator

1. Enter the power output in kW.
2. Enter the engine displacement in liters.
3. Enter the engine speed in RPM.
4. Optionally set revolutions per power cycle (2 for four-stroke, 1 for two-stroke).
5. Click Calculate to get the mean effective pressure in kPa.

Related Calculations

Use with the Engine Power from Fuel Calculator to trace power back to fuel input.