Schwarzschild Radius Calculator: Black Hole Event Horizon Size

Schwarzschild Radius Calculator

Calculate the event horizon radius (Schwarzschild radius) of a black hole based on its mass.

Object Mass

Unit

Radius (Kilometers) 2.9542 km

Radius (Meters) 2.9542e+3 m

What is the Schwarzschild Radius?

The Schwarzschild radius is the radius of the event horizon of a non-rotating black hole. If an object is compressed below this radius, its escape velocity exceeds the speed of light, and it becomes a black hole.

The Formula

The radius is calculated using the formula: Rs = 2GM / c², where G is the gravitational constant, M is the mass of the object, and c is the speed of light.

Frequently Asked Questions (FAQ)

Can anything escape from within this radius?

According to general relativity, nothing—not even light—can escape once it crosses the event horizon.

What is the Schwarzschild radius of the Sun?

The Sun's Schwarzschild radius is approximately 3 kilometers.

How it Works

The calculator uses the Schwarzschild formula Rs = 2GM/c², where G = 6.67430×10⁻¹¹ m³ kg⁻¹ s⁻² is the gravitational constant, M is the object's mass, and c = 299,792,458 m/s is the speed of light. When you select solar masses, the input is first converted using the solar mass of 1.989×10³⁰ kg, and the resulting radius is displayed in both kilometers and meters.