Have a look at the Hawking Radiation Calculator, which you'll have to search for yourself since I evidently haven't made enough posts yet to post links.

You can plug in a value for whatever parameter you'd care to investigate and see how it affects everything else. If you want a black hole that lasts for a few hours, that's a mass of around six million kg. If you want one that lasts around ten billion years, that would correspond to a mass of around 190 billion kg.