DEPTH: HOW DEEP IS DEEP ENOUGH?
Depth is another key measurement to know for cooking with your favorite skillet. It’s less important for things like searing a steak or roasting vegetables, but when it comes to baking, frying, and even sautéing, the depth of a pan is a key player in recipe success or failure. To measure your pan, place the base of a ruler at the inside base of the pan and hold it up to the sides. Never measure depth from outside the pan, as a thicker base could give the appearance of more depth than is actually available for cooking.
In most cases, standard skillets are about 2 inches deep. This size is high enough to keep cake and cornbread batter from spilling over the sides but not so high that a spatula has a hard time getting into the edges of the pan. This size is also appropriate for shallow frying. But when you want to heat more than an inch of oil, you need a skillet that is 3 to 4 inches deep to safely cook and fry. If you want to deep fry, a Dutch oven is your best bet.