Carnot Efficiency Calculator
Calculate maximum heat engine efficiency from reservoir temperatures.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
Can't find what you need?
Request a ToolHow to Use the Carnot Efficiency Calculator
Enter the hot and cold reservoir temperatures and select the temperature unit (Kelvin, Celsius, or Fahrenheit). The calculator computes the maximum theoretical efficiency and shows the waste heat fraction.
About Carnot Efficiency
The Carnot cycle, proposed by Sadi Carnot in 1824, defines the theoretical maximum efficiency of any heat engine. It depends only on the absolute temperatures of the hot and cold reservoirs. The efficiency equals 1 minus the ratio of cold to hot temperature (in Kelvin). This fundamental limit of thermodynamics explains why power plants, car engines, and refrigerators can never be 100% efficient. It guides engineers in maximizing real-world engine performance.
Frequently Asked Questions
What is Carnot efficiency?
Carnot efficiency is the maximum possible efficiency of a heat engine operating between two temperature reservoirs. No real engine can exceed this limit. It equals 1 - Tc/Th where temperatures are in Kelvin.
Why can no real engine reach Carnot efficiency?
Real engines have irreversibilities such as friction, turbulence, and finite-rate heat transfer. These losses always reduce efficiency below the Carnot limit.
How can Carnot efficiency be increased?
Increase the hot reservoir temperature or decrease the cold reservoir temperature. In practice, material limits and environmental temperature constrain both values.