How can you tell if a fuse is burned out?

You can tell if a fuse is burned out by visually inspecting it; a blown fuse often has a broken metal strip or a darkened glass window. Additionally, you can use a multimeter set to the continuity setting; if the meter shows no continuity when testing the fuse, it is likely burned out. If the fuse is part of a circuit that no longer works, that is another indication it may need replacing.