Selecting an ideal enamel mug involves considering both its dimensions and how much it holds. A typical enamel mug is around 3 to 4 inches in diameter, with a depth that can vary from 4 to 6 inches. When it comes to capacity, most enamel mugs hold between 10 and 16 ounces of liquid. To ideally choose an enamel mug, imagine how you'll be using it.