Black Hole Calculator
What if Earth was compressed into a black hole? It would be just 1.8 centimetres across, about the size of a marble! The Schwarzschild radius is the size an object must be compressed to become a black hole. Enter any mass to find its event horizon size, or explore how black holes scale with mass.
How We Calculate This
Schwarzschild radius Rs = 2GM/c², where G = 6.674×10⁻¹¹ m³/(kg·s²), M is mass, and c = 299,792,458 m/s. Density calculated assuming uniform sphere: ρ = 3M/(4πRs³).
Frequently Asked Questions
What is the Schwarzschild radius?
The Schwarzschild radius is the radius of the event horizon of a non-rotating black hole. Any mass compressed within this radius becomes a black hole, from which not even light can escape.
Could Earth become a black hole?
Only if compressed to about 1.8 cm diameter. No natural process can do this. Black holes form when massive stars (>25 solar masses) collapse, not from planets.
Why do larger black holes have lower density?
Schwarzschild radius scales linearly with mass (R ∝ M), but volume scales with radius cubed (V ∝ R³). So density ∝ M/R³ ∝ 1/M². Supermassive black holes have surprisingly low average densities, sometimes less than water!
What happens at the event horizon?
At the event horizon, escape velocity equals the speed of light. Nothing can escape once crossed. To an outside observer, objects appear to freeze at the horizon due to extreme time dilation.
What is the largest known black hole?
TON 618 is estimated at 66 billion solar masses, with an event horizon about 1,300 AU across, larger than our entire solar system out to the Kuiper Belt.
Related Calculators
You might also find these calculators helpful: Escape Velocity, and Weight on Other Worlds.