🕳️ Black Hole Temperature Calculator
Enter a black hole’s mass to calculate its theoretical Hawking radiation temperature, using Stephen Hawking’s formula for black hole thermodynamics.
What is Hawking temperature?
Stephen Hawking predicted that black holes aren’t perfectly black: quantum effects near the event horizon cause them to slowly emit thermal radiation, giving them an effective temperature that depends inversely on their mass. Smaller black holes are hotter; larger ones are colder.
The formula
The Hawking temperature is T = (ħ × c3) ÷ (8π × G × M × kB), where ħ is the reduced Planck constant, c is the speed of light, G is the gravitational constant, M is the black hole’s mass, and kB is Boltzmann’s constant.
For a stellar-mass black hole this temperature is far colder than the cosmic microwave background (about 2.7 K), meaning such black holes absorb far more radiation than they emit and would take vastly longer than the current age of the universe to evaporate. This calculator is for general astrophysics education.