Because of the variations in sizes and brands of pizza, it is best to cook a pizza according to the manufacturer's instructions found on the box. In general, pizza should cook on the middle rack of the oven at a very high temperature for no more than 30 minutes.
For example, a 12-inch Original Rising Crust Pizza from DiGiorno bakes at 400 degrees Fahrenheit for between 22 and 26 minutes on the center oven rack for a crisp crust, and between 25 and 29 minutes for a softer crust.
Meanwhile, an 8-inch Totino's Pizza with Canadian Style Bacon should bake for 14 to 15 minutes on the middle rack in a 425-degree oven. For a softer crust, it's important to bake the pizza on a cookie sheet for up to 19 minutes.