Carnot Efficiency Calculator

The calculation is based on the second law of thermodynamics, formulated by Nicolas Léonard Sadi Carnot. The efficiency (η) depends entirely on the absolute temperatures of the hot and cold reservoirs, measured in Kelvin. The fundamental equation is:

η = (T_hot - T_cold) / T_hot

Where T_hot is the absolute temperature of the heat source and T_cold is the absolute temperature of the heat sink. Because absolute zero is impossible to reach in reality, no real-world engine can ever hit 100% efficiency.

Imagine a steam power plant where the boiler provides a hot reservoir temperature of 800 Kelvin (K), and the nearby river serves as a cold reservoir at 300 K. To find the maximum theoretical efficiency, apply our formula step-by-step:

1. Subtract the cold temperature from the hot temperature: 800 K - 300 K = 505 K (numerator).
2. Divide that difference by the hot reservoir temperature: 500 / 800 = 0.625.
3. Convert the decimal into a percentage by multiplying by 100: 0.625 × 100 = 62.5%.

This means under these exact thermal conditions, the engine cannot convert more than 62.5% of the input heat into useful work, regardless of how well-designed or frictionless the mechanical parts are.

Always convert Celsius or Fahrenheit temperature readings into Kelvin (or Rankine) before executing the calculation. Using relative temperature scales will yield entirely incorrect thermodynamic outputs. Additionally, remember that Carnot efficiency represents an idealized limit; real engines experience internal friction, turbulence, and thermal losses that drop their operational performance well below this theoretical ceiling.