The primary advantage of a four-slice toaster is that it allows the user to cook twice as much toast in the same amount of time. Since bagels, English muffins and other items also cook in a toaster, a four-slice toaster increases the number of options for browning at once.
It is not necessary to use all four slots at the same time. Some toasters offer the chance to use two slots at a time to save electricity. Options such as variable browning control, wider and longer slots and mini-cycle cancel function make a four-slice toaster even more versatile. Some models allow the user to lift the toaster lid and look at the bread as it is cooking.