"Large" and "extra-large" eggs may seem like labels used by egg manufacturers to make their products look appealing, but egg sizes in America are actually regulated by the U.S. Department of Agriculture. These are differences between large and extra-large eggs in terms of size and weight, and what it means for your cooking.

The USDA allows for variation in individual egg weights, but a dozen eggs have to weigh a certain amount for the carton to be labeled "large" or "extra large." A dozen large eggs must weigh around 24 ounces, while a dozen extra large eggs must weigh 27 ounces; on average, an XL egg is 0.5 ounces heavier than a large egg.

Most of the time, the difference between a large egg and an extra large egg will not matter much in a recipe, so you can use these eggs interchangeably. However, if you're baking and a recipe calls for six eggs or more, the small differences in weight and volume will add up, and you'll be better off sticking to the size called for in the recipe.

You can also use a digital food scale to get the most accurate measurements when cooking with egg yolks or whites. Past research by Cook's Illustrated showed that for large eggs, the average yolk weighed .54 ounces, and the average whites were 1.19 ounces; for extra-large eggs, the yolk averaged 0.57 ounces and the whites 1.33 ounces.