One way to tell if the shoes are too big, too small, or just the right fit is by walking in them. If you can’t tell that immediately, then wear the shoes for a few minutes around your house. If they are of the wrong size, you should know it within a few hours of wearing them. Unless it is a sports shoe, make sure that there is enough wiggle room for your toes inside. The exact fit of sports footwear varies across different sports. The back of your feet should not be too tight against the shoes either. Putting a finger inside is one way to try the fit of the shoes. If you cannot slide in your finger at all, then the shoes are too small. Meanwhile, if you can put your finger in without any resistance, then go for the smaller size.