Eggs sold in stores are usually (but not mandatorily) classified by United States Department of Agriculture (USDA) grades. Egg grade has nothing to do with either freshness or size, and is not a guarantee of egg quality in your kitchen. Itβs an approximate indication of the quality of the egg back at the ranch, at the time it was collected. Because candling isnβt foolproof, USDA definitions allow several eggs per carton to be below grade at the time of packing. Once the eggs have arrived in stores, the below-grade allowance doubles, because egg quality naturally declines with time, and jostling and vibration during transport can cause the white to thin out.