How do you determine the magnifying power of microscope?

There are a number of objectives on the nose piece, usually there are three of them. You can either look at those, to see if they have the magnifying power printed on it, or you can read the instructions, if they came with your microscope. Average microscopes usually have a maximum of 200 or 400x magnifying power. Note: Microscopes have about 3 different magnifying powers. Most are 40x, 100x, and 200 to 400x.