Black Hole Event Horizon Calculator

Calculate Schwarzschild radius, event horizon, ergosphere, Hawking temperature, and black hole parameters.

Black Hole Mass

Solar Masses

Spin Parameter

Tab to move between fields

Schwarzschild Radius

2,954.127 m

≈ 9 Eiffel Towers

Event Horizon Radius

2,954.127 m

≈ 9 Eiffel Towers

Hawking Temperature

0.000000062 K

Hawking Lifetime

20,973,585,980,140,658,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 years

Ergosphere Radius2,954.127 m

How to Use This Calculator

Enter the Black Hole Mass in solar masses — stellar black holes are 3–100 M☉, supermassive ones are millions to billions.
Set the Spin Parameter (0–0.99): 0 is a non-rotating Schwarzschild black hole; values near 1 are maximally spinning Kerr black holes.
Read the Schwarzschild Radius (m) and Event Horizon Radius (m) — for a spinning hole these differ due to frame-dragging.
Note the Hawking Temperature (K) — stellar-mass black holes are effectively at absolute zero; only micro black holes radiate detectably.
Use Hawking Lifetime (years) to understand evaporation timescale — a solar-mass black hole evaporates over ~10⁷⁴ years.

How the result changes with Black Hole Mass

Black Hole Mass	Schwarzschild Radius	Event Horizon Radius
100,000	295,412,655.506 m	295,412,655.506 m
350,000	1,033,944,294.269 m	1,033,944,294.269 m
650,000	1,920,182,260.786 m	1,920,182,260.786 m
900,000	2,658,713,899.55 m	2,658,713,899.55 m

Black Hole Mass: Mass of the black hole
Spin Parameter: Angular momentum parameter (0 = non-rotating, <1 = rotating)

r_s = 2GM/c² (Schwarzschild Radius)

Identify Input Parameters
Black Hole Mass = 1, Spin Parameter = 0 = 2 input(s) provided
Calculate Schwarzschild Radius
Schwarzschild Radius
2954.127 = 2954.127
Calculate Event Horizon Radius
Event Horizon Radius
2954.127 = 2954.127
Calculate Hawking Temperature
Hawking Temperature
6.2e-8 = 6.2e-8
Calculate Ergosphere Radius
Ergosphere Radius
2954.127 = 2954.127