The singularity is a dimensionless object. It is a point in space. We aren't certain what exactly that point looks like, but we do know it's a point. It has no length, width or height.
So to describe a black hole's size, is to refer to the event horizon, a boundary which is dictated by the black holes mass and spin.
gimleychuckles t1_iv3yxmm wrote
Reply to comment by jmb2k6 in Closest known black hole to Earth spotted by astronomers by lunarmoonr
The singularity is a dimensionless object. It is a point in space. We aren't certain what exactly that point looks like, but we do know it's a point. It has no length, width or height.
So to describe a black hole's size, is to refer to the event horizon, a boundary which is dictated by the black holes mass and spin.