How much can a black hole weigh?

They can 'weigh' anything from 0.00001 grams to nearly the mass of the entire visible universe.

The ones astronomers see are either in the mass range from 1 - 10 times the mass of the Sun, or 1 million to a few billion times the mass of the Sun.

Recently, black holes have been discovered in the cores of globular clusters with intermediate masses of about 10,000 solar masses.