Work out the surface area of a non-spinning black hole and you’ll get the answer:
But ask what volume this surface contains and you’re in for a surprise. Turns out that the volume depends on how the 3-space within the black hole is defined. Now Brandon DiNunno and Richard Matzner from the University of Texas at Austin have performed the calculations for various definitions of 3-space and show how the volume of black hole can be time-dependent and even, in certain circumstances, zero.
Yep, that’s zero!
Ref: arxiv.org/abs/0801.1734: The Volume Inside a Black Hole