Black Hole Size Comparer

How big is a black hole, really? Pick a famous one or enter any mass to see the size of its event horizon next to the Earth, the Sun and the solar system.

How this works

The event horizon of a non-spinning black hole has a radius of about 2.95 km for every Sun of mass (the Schwarzschild radius, 2GM/c²). Spinning black holes differ somewhat. The chart uses a logarithmic scale, so each gridline is ten times bigger than the last.

Masses are published estimates and can change: Cygnus X-1 about 21 Suns (Miller-Jones et al., 2021); Sagittarius A* about 4.3 million (GRAVITY collaboration); M87* about 6.5 billion (Event Horizon Telescope, 2019); TON 618 roughly 40 billion (estimates range up to about 66 billion); J0529-4351 about 17 billion (ESO, 2024). See also What is a black hole?