A reader asked: “Grocery stores are now selling extra large eggs. Do I have to worry about equivalencies in recipes?”

Here’s how egg sizes are measured and when you need to factor different sizes into your cooking.

While large eggs are the most common, other sizes aren’t anything new. There are peewee, small, medium, large, extra large and jumbo eggs. “Size tells you the minimum required net weight per dozen eggs,” according to the Agriculture Department. “It does not refer to the dimensions of an egg or how big it looks.”

It’s important to note that these distinctions are based on the weight of a dozen eggs – not of an individual egg – so you might find variances within a single carton.

Egg sizes (weight per dozen)

• Jumbo: 30 ounces
• Extra large: 27 ounces
• Large: 24 ounces
• Medium: 21 ounces
• Small: 18 ounces
• Peewee: 15 ounces

Using eggs in recipes

In recipes that call for eggs, the preparation will often determine whether you should take egg size into account. For the most basic methods – scrambling, poaching, boiling, etc. – use whatever size you have on hand. In other recipes, particularly baking, you need to be more cautious.

Unless otherwise specified, recipes typically are designed with large eggs in mind. “Using a different size, without making an adjustment, will affect texture, flavor balance, consistency, and in most cases will give an unsatisfactory result,” according to the American Egg Board, which has a handy chart for making appropriate conversions, such as using two jumbo eggs as a substitute for three large eggs (incredibleegg.org, under “Cooking Lessons”).