On a carton of eggs you might have noticed words like Cage-Free, Grade A, Large, and Brown, one after another. Open Nature's carton in Safeway's egg case carries all four at once. Some of those words are backed by a USDA inspection. Others are just printed on the box, with nobody required to prove them. Here's what each one means.

Open Nature Eggs Cage Free Large Grade A Brown

What Cage-Free, Free-Range, Pasture-Raised, and Organic Mean

Cage-Free means the hens live uncaged, with unlimited food and water and room to move around their enclosure. That's the whole requirement. It doesn't promise any amount of space per hen, and it doesn't mean the hens ever go outside. A cage-free barn can still be a crowded one.

Free-Range starts from the same rules and adds outdoor access, but USDA never says how much. There's no minimum space and no minimum hours, so a covered porch attached to the barn can satisfy it.

Pasture-Raised is the one term here that USDA doesn't define at all. Any producer can print it on a carton. The words become enforceable only when a certification logo sits next to them, like Certified Humane or American Humane Certified. Certified Humane, for example, requires its pasture-raised farms to give each hen 108 square feet of outdoor space, vegetation to forage in, and at least six hours outside a day, weather permitting. Without a logo like that, pasture-raised is a claim nobody has to verify.

Organic is the one term backed by a federal inspection program. A farm carrying the USDA Organic seal has to give its hens outdoor access year-round, feed them 100% certified organic feed grown without synthetic pesticides or GMOs, and raise them without antibiotics or added hormones. The outdoor space has to be at least 75% soil, with vegetation where the land allows it. Hens can be confined temporarily, but only for a documented health or environmental reason, and an inspector audits all of it. Nobody audits a cage-free barn the same way. One reviewer of the O Organics carton, headed "Good egg," describes "eggs from free range hens, on organic feed" in "colorful cardboard, no plastic."

O Organics Organic Eggs Large Brown

What Grade AA, A, and B Mean

A grade is a USDA quality check on the shell and the inside of the egg. Grading is voluntary. Producers pay USDA for it, so a grade shield on the carton means an inspector passed that lot. It says nothing about how the hens were raised, and nothing about size. A dozen Grade AA eggs can be small, large, or jumbo.

Lucerne Farms Eggs Extra Large Grade A

Grade AA is the top mark. Cracked onto a flat surface, the white stands thick and firm around a rounded yolk, and the air pocket inside the shell is barely there. Grade A meets the same clean-shell standard, with a slightly deeper air pocket and a white that spreads a little more. Those two are what you'll see at the store. Grade B, with its stained shells and thinner whites, mostly skips the shelf and goes into the liquid egg used by packaged foods and food service. Shoppers tend to judge that quality by how the eggs show up. One reviewer of the Lucerne large eggs, headed "AA+ for AA Eggs," noted they arrived "so fresh" with "at least 3 weeks left before the code date."

Lucerne Eggs Large Grade A Family Pack

Egg Sizes, and Why Recipes Call for Large

Egg sizes are set by the weight of a dozen, and USDA defines six of them:

Recipes assume large eggs. Large has been the American baking standard for decades, and the nutrition facts printed on the carton are based on a large egg too, about 2 ounces of it. The sizes step up by a quarter ounce per egg, so a three-egg cake batter made with jumbos picks up about an extra ounce and a half of liquid, enough to change the texture. In scrambled eggs or an omelet you'd never notice. Bakers notice the size on the shelf. One reviewer of the extra-large Lucerne eggs, "Right size for baking cakes etc," writes that "large sized eggs are not very consistent and sometimes too small for cake."

Lucerne Farms Eggs Large

Peewee and small have mostly vanished from retail. Safeway's case runs large, extra-large, and jumbo, stacked side by side.

Lucerne Farms Eggs Jumbo Grade A

Brown Eggs vs. White Eggs

Shell color is a breed trait. White Leghorns, the standard commercial layer in the U.S., have white feathers and white earlobes and lay white eggs. Rhode Island Reds, Plymouth Rocks, and the other brown-egg breeds have red feathers and red earlobes. The brown is a pigment the hen deposits on the shell just before laying, and under it every egg is white.

Brown eggs often cost a little more because brown-egg breeds are bigger hens that eat more feed. The difference is in the bird, and it ends there. No study has found a nutritional or taste difference between brown and white eggs of the same size, grade, and diet.

Lucerne Eggs Brown Large A