You are standing in the kitchen, about to make a massive omelet or bake a cake. You find a carton of eggs in the back of the fridge, but the printed expiration date is smudged. Breaking a rotten egg into your mixing bowl instantly ruins the entire dish with a horrific smell.
You don’t need to guess, and you don’t need to crack them open to check. You can scientifically test the freshness of an egg in 10 seconds using The Float Test.
How the Science Works:
Eggshells are highly porous (they have thousands of microscopic holes). As an egg ages, the liquid inside slowly evaporates through these pores, and outside air enters to replace it. This creates a growing air pocket at the bottom of the egg. The older the egg, the larger the air pocket, and the more buoyant it becomes.
1. The Sinker (Very Fresh)
If the egg sinks straight to the bottom and lays perfectly flat on its side, it is incredibly fresh. This is perfect for sunny-side-up frying or poaching, as the whites are still tight and hold their shape.
2. The Stand-Up (1 to 2 Weeks Old)
If the egg sinks to the bottom but stands upright on one end, it is aging but is still perfectly safe to eat. In fact, these eggs are the absolute best for making hard-boiled eggs! The slight air pocket makes the shell separate from the membrane, meaning they will peel effortlessly.
3. The Floater (Spoiled)
If the egg immediately floats to the surface of the water and bobs at the top, the air pocket is massive. The egg has spoiled and is no longer safe to consume. Throw it straight into the compost bin!
