How can two egg-cartons at the grocery store be exactly alike (you stand there and stare), yet one is priced higher? It seems like a trick, but no: Egg size isn’t just about how much space they take up; it’s also about their chemistry. The USDA grades its protein according to weight per dozen, not by actual size. You might not notice the difference between a large and a medium, but that makes a difference when you cook with them. That is what this chart illustrates: How the weight translates into reality.
Most recipes are based off the idea of large eggs to provide an even ratio of white to yolk. That is why they call for them; it ensures you have the correct amount of liquid needed for the result, whether it is a custard or a cake. Sure, jumbo eggs may feel like they give you more bang for your buck, but you’re changing the composition inside the recipe itself. Extra liquid will break up curds in sauces, and yield denser results in baked goods. It is a little thing, but it is important for delicate preparations.
Why Egg Size Matters in Cooking
So when do size swaps work? Here’s why: Inside an egg, there are two components, the yolk (which contains most of the flavor and fat) and the egg white (which gives it its lift and structure). When an egg is larger, though, its shell grows at a slower rate then the volume inside. In other words, bigger eggs tend to be a bit more delicate (at least during handling), since they have relatively thinner shells compared to what’s inside of them. And perhaps that’s why older hens lay bigger eggs: They don’t make as much calcium, which goes into the shell. This is why jumbos so frequently feel heavier in-hand yet fracture so easy when dropped.
But what if you’re stuck with medium eggs? Good news: You can still substitute them by adding more to account for the difference in volume. As long as you add a few more to make up for the difference, it’ll all work out.
Here’s why: For all practical purposes, nutritional value scales roughly proportionally with size (i.e., three medium eggs = ~two large = ~one extra-large). Regardless of which size you purchase, small, jumbo, etc., you’re getting about the same amount of vitamins, minerals, fat, carbs, sodium, etc., per egg. The single exception is cholesterol; larger eggs contain slightly higher levels than smaller eggs, but this isn’t going to affect anyone who’s not already a walking cardiovascular event. And that’s where most folks go wrong when they assume bigger eggs mean more nutrition per egg.
What if you’re stuck with medium eggs? Don’t worry, you can still use ’em
And then there are storage habits: Storing eggs correctly helps preserve that structure once you bring them home. Use the same carton and put them on the middle shelf of your fridge (not in the door; that part of the fridge gets crazy hot/cold whenever you reach for the milk). If left out of the carton, the porous shell will absorb aromas from stinky items like fish or onion.
To see if an egg has gone bad without cracking it open, give it a float test: Fresher eggs sink to the bottom of the bowl because they have less air space than older eggs. The air cell expands as moisture is lost, so older eggs float to the top. Simple physics, and no more spoiled breakfasts.
And then there’s time: Size matters there too, a larger egg takes longer to boil than a smaller one (the heat has further to travel through the mass of an extra-large egg before it reaches the desired level of doneness). Following a generic timer and not making allowances for size means that your yolks might still be raw while the whites is cooked to death. Always make allowance for size when you’re planning your dish. It’s mostly a mental game, as we tend to treat all eggs as the equivalent of the spherical uniform object that they aren’t biologically speaking.
Last but not least: Don’t stress over shell color. White, brown, blue, even speckled, the shell color you see depends entirely upon the genes of the hen breed; it has nothing to do with whether she has access to pasture or high-quality feed. Just because an eggshell is brown doesn’t make it taste more “rustic” than if it’s white (as much as marketing would of us believe). What determines the nutritional value isn’t the shell at all… But what is inside.
When filling up your pantry, pay attention to size and freshness. Not how pretty it looks. The next time you crack an egg onto your griddle, watch what it does when it hits the pan. What kind of splat? How old is that sucker, really? Whether you are frying eggs for breakfast or baking a sponge cake, knowing the egg size ensures you get exactly what you want for your dish. The shell doesn’t matter; only the contents do.