There are black holes as little as 0.1 millimeter
It’s easy to think that black holes are massive spaces that can consume objects much greater than the Earth or even the solar system. However, there are super small black holes, and scientists have studied them.
The smallest known black hole measured at 0.1 millimeters at its core. However, it is not its whole mass if you account for the inner and outer horizons. The smallest recorded black hole, including the whole mass and all layers, is 22 micrograms, and even with that, there is a possibility of expansion as it orbits around. A microgram is one-millionth of a gram, so just visualize that.