How do I determine how slowed down high-speed footage is?

Every time some blog or TV show or some foolish thing has some high-speed footage to show in slow motion, like a bullet shooting through a grape or a drop of water splashing or something inane like that, they only quantify it as how many frames per second the camera can shoot. That doesn't say anything about how slowed down the video they're showing me is. How do I determine that?