Carnot Efficiency Calculator

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Choose what you want to solve for. The inputs will adjust to match.
All temperatures are converted to Kelvin internally before calculation.
Temperature of the heat source (boiler, combustion chamber, etc.). Must be strictly greater than Tc.
C
Temperature of the heat sink (cooling water, ambient air, etc.). Must be strictly less than Th.
C
Carnot efficiencyHigh efficiency
61.44%

Maximum possible efficiency for any engine between these two temperatures

Hot reservoir (K)773.15K
Cold reservoir (K)298.15K
Tc / Th ratio0.3856
COP - heat pump1.63
COP - refrigerator0.63
61.44% %
Very low (<20%)<20%Low (20-40%)20%-40%Moderate (40-60%)40%-60%High (60-80%)60%-80%Very high (>80%)80%+

The Carnot efficiency is 61.44%.

  • The temperature difference between reservoirs is 475.0 K. A larger spread always raises the Carnot ceiling.
  • Used as a Carnot heat pump this cycle could deliver 1.63 units of heat for every unit of work - far above what direct electric heating achieves.
  • The same cycle run as a refrigerator would move 0.63 units of heat out of the cold space per unit of work input.
  • No real engine can exceed the Carnot efficiency because it represents the thermodynamic limit set by the Second Law.

Next stepCompare this theoretical maximum with your engine's datasheet efficiency to quantify losses from friction, heat leaks, and irreversible processes.

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