Kitchen Mysteries is a weekly exploration of oddities surrounding cooking and food. They could be recipes that fail when they shouldn't, conflicting advice from different sources, or just plain weirdness. If it happens in a kitchen, and you're not sure why, send a tweet to The Food Geek to find out what's happening.
Elizabeth asks via twitter:
The size labels for eggs are a bit misleading. The USDA size guidelines don't have anything to do with the volume of the egg directly. In fact, the USDA "size" guidelines are determined by how heavy a dozen eggs are.
According to a USDA PDF on choosing eggs that I found, sizes go something like this:
- Jumbo eggs are at least 30 ounces to the dozen.
- Extra large eggs are at least 27 ounces to the dozen.
- Large eggs are at least 24 ounces to the dozen.
- Medium eggs are at least 21 ounces to the dozen.
- Small eggs are at least 18 ounces to the dozen.
- Peewee eggs are at least 15 ounces to the dozen.
There's even a "peewee" egg size. That's fantastic.
Most recipes call for large eggs, probably partially because it's a very common egg size, but probably mostly because there are 24 ounces to the dozen, which means that it's 2 ounces per egg. This means that if you're baking a dish that requires 3 large eggs, what you really want is 6 oz of eggs.
I wouldn't stress too much if you can't find the exact combination of eggs to give you the proper weight, as there's about 6 ounces of difference between medium eggs and extra large eggs, which is 1/4 of the weight of a dozen large eggs. This means that, even with large eggs, 3 eggs could be between 5.25 ounces and 6.75 ounces. You have some leeway.