♨️ Carnot Efficiency Calculator
Find the theoretical maximum efficiency of a heat engine from its hot and cold reservoir temperatures (η = 1 − T_c/T_h).
Efficiency η
0.5 (50.00%)
Carnot (maximum) efficiency: η = 1 − T_cold/T_hot, with temperatures in kelvin. Real engines fall below this limit. 🔒 Computed in your browser.
How the carnot efficiency calculator works
The Carnot efficiency is the highest any heat engine can achieve between two temperatures: η = 1 − T_cold/T_hot, with both temperatures in kelvin. Enter the two reservoir temperatures and the tool gives the efficiency (as a fraction and percentage); real engines always fall below this ideal limit.
Temperatures must be absolute (kelvin). No real engine reaches Carnot efficiency because of friction, irreversibility and finite heat transfer — it’s an upper bound.
Frequently asked questions
What is Carnot efficiency?
The maximum possible efficiency of a heat engine operating between two temperatures: η = 1 − T_cold/T_hot (in kelvin). It sets the ceiling no real engine can beat.
How do I calculate it?
Divide the cold-reservoir temperature by the hot-reservoir temperature (both in K) and subtract from 1. For T_h = 600 K and T_c = 300 K, η = 1 − 0.5 = 0.5 (50%).
Why must temperatures be in kelvin?
The formula uses absolute temperature ratios, which only make sense from absolute zero. Convert with K = °C + 273.15.
Can a real engine reach Carnot efficiency?
No — friction, heat loss and irreversibility always make real engines less efficient. Carnot is a theoretical maximum, useful as a benchmark.
How can I raise the efficiency?
Increase the hot temperature or decrease the cold temperature (a larger gap). That’s why power plants run boilers as hot as materials allow.