All about eggs: Colors, sizes and grades

There’s much that meets the eye when you look at a chicken egg.

Egg colors

Ever noticed how some chicken eggs are different colors? It’s all due to genetics, according to Michigan State University Extension. All eggs are originally white. As eggs travel through the hen’s oviduct, pigments may be deposited on them, changing the color.

When we think of eggs, most people picture a white-shelled egg, but eggs can also be blue, green or shades of brown.

Leghorns lay white eggs. Ameraucanas lay blue eggs. Olive eggers lay olive green eggs. And Orpingtons lay brown eggs.

Check out photos of the colors of eggs laid by different chicken breeds on Backyard Chickens.

Egg nutrition

The color of an egg’s shell does not determine its nutritional value, explains the USDA Food Safety and Inspection Service.

University of Illinois Extension adds that if hens have eaten the same ration, then the eggs will have the same nutritional quality, even if the shells are different colors. In addition, egg cooking qualities and flavor-keeping qualities will remain the same, regardless of shell color.

Egg sizes

Eggs come in different sizes. The USDA Food Safety and Inspection Service explains that the size noted on a carton of eggs indicates the required minimum weight per dozen of eggs, not the individual size or appearance of the eggs. The sizes of eggs are as follows:

• Jumbo 30 oz.
• Extra Large 27 oz.
• Large 24 oz.
• Medium 21 oz.
• Small 18 oz.
• Peewee 15 oz.

Egg grades

There are three U.S. egg grades, according to The USDA Food Safety and Inspection Service: AA, A and B.

U.S. grade AA and U.S. grade A are the two grades you see in the supermarket, with grade A being the most common.

U.S. grade AA eggs have thick, firm whites. The yolks are high, round and defect-free. U.S. grade AA egg shells are unbroken.

U.S. grade A eggs are similar to grade AA eggs, but the whites are considered “reasonably firm.”
U.S. grade B grade eggs are typically not sold in stores. These eggs are used for liquid, frozen and dried egg products. U.S. Grade B eggs have thinner yolks and whites than U.S. grade A and AA eggs. The yokes and whites may also be wider and flatter than higher grade eggs.