The size of an A egg is determined by weighing a dozen eggs. These measurements are used in the United States. Different methods may be used in other regions and countries.
Guide to Egg Measurements in the US
The smallest is the peewee, with a dozen eggs weighing 15 ounces. Next is small at 18 ounces. The medium size eggs are 21 ounces followed by the large at 24 ounces. The extra large eggs are 24 ounces. The biggest is the jumbo at 30 ounces.
Grading is used to determine the quality of the egg. The highest quality is AA followed by A and B. To qualify as an AA egg, the shell must be of regular shape. It cannot have blemishes or cracks. Internally, the whites have to be firm and clear. The yolk cannot have any blemishes.
No matter what the size of an A egg is, it must meet the following requirements. The shell cannot be broken and must be clean. The shape has to be normal. There are some differences with the AA however.
Whereas the air cells in AA eggs cannot be more than 1/8”, it can be 3/16 in A variants. While the AA classification requires firm whites, the A eggs only require them to be reasonably so. The yolk must be blemish free.
The B eggs are usually not sold to the general public. Instead, they are utilized to make liquid or dried egg products. Unlike AA and A eggs, the yolk will be flat, dark or larger than normal. The whites are watery rather than firm.
Grading may be conducted by state or federal officials. The process has to follow the guidelines imposed by the USDA. The test involves examination of the internal and external parts of the egg.
What Size and Type to Use
While AA is the highest quality, the grade A eggs are perfectly acceptable. For basic recipes like fried or scrambled eggs, any size will do. Baking recipes however, require more precision.
Usually they need eggs of the large variety. They may also require specific amounts of whites and yolks. If the recipe requires other sizes like small or jumbo, you can get them in supermarkets.
If you are just preparing simple recipes, the size of an A egg is not that important. Only when baking will the size matter. While A types are still good, the AA is the best option.