How long does it take to make a black hole?

The process of forming a black hole is not well understood, and it depends on a variety of factors, such as the mass and density of the collapsing object. In general, a black hole can form in one of two ways:

Stellar collapse: When a massive star runs out of fuel, it can no longer support its own weight against gravitational collapse, and it will start to collapse in on itself. If the star is massive enough (at least three times the mass of the sun), the collapse can continue until the star’s core is compressed into a point of infinite density known as a singularity, surrounded by a boundary called the event horizon. This marks the birth of a black hole. This process can take anywhere from a few milliseconds to a few seconds.

Accretion: A black hole can also form from the accretion of matter onto a dense object such as a neutron star or white dwarf. As matter accumulates, it can increase the object’s mass and gravity, eventually causing it to collapse into a black hole. The time it takes for this process to occur depends on the rate at which matter is being accreted and the mass of the object.


In summary, the time it takes to form a black hole depends on the initial conditions and the method by which it is formed. The collapse of a massive star can result in the formation of a black hole in a matter of seconds, while the accretion of matter onto a dense object can take millions of years to reach the critical mass needed to form a black hole.