Stirling Cycle Efficiency Calculator

About this calculator

The Stirling cycle efficiency calculator computes the ideal thermal efficiency of a Stirling engine operating between a hot reservoir temperature Th and a cold reservoir temperature Tc, using η = 1 − Tc/Th (both temperatures in kelvin). Remarkably, this is exactly the Carnot efficiency — the theoretical maximum for any heat engine operating between those two temperatures — because the Stirling cycle's isochoric heat exchanges are assumed to happen through perfect regeneration, with no net entropy generated during them.

Real Stirling engines never hit this ideal number because regeneration is never perfect and there are always friction, heat-transfer, and pressure losses, but the theoretical ceiling still guides design decisions about temperature range and regenerator quality. Mechanical engineers designing Stirling engines for solar-thermal power, cryocoolers, or combined-heat-and-power units, and thermodynamics students use this calculator to find the theoretical efficiency limit before accounting for real-world losses.