Here is a simple way to tell if you eggs are still good and safe to eat.
This simple rule is – if they float – like the dead man’s float – get rid of them. If they sink – they are a keeper!
Eggshells are porous, allowing air to slowly get in over time. As more air enters the egg, it gets lighter and lighter, which explains why it will eventually float. Fresh eggs have less air in them, so they sink to the bottom. But older eggs have had more time for the air to penetrate the shells, so they’re more buoyant and will float.
Above you can see a fresh egg (little air space, slightly visible yolk), a slightly old egg (larger air space, slightly darker yolk), a nearly bad egg (really dark yolk, spotty), and a spoiled egg (mixed in yolk, lots of dark)
The Best Method for Cracked Eggs: The Plate & Sniff Test
If you don’t need the shell intact, you can also crack the egg onto a plate or other flat surface to test how fresh it is. If it’s fresh, the yolk should be bright yellow or orange and the white shouldn’t spread much. If you’re not sure, give it a good sniff: fresh eggs shouldn’t have much of a smell at all.
If the egg is older, the yolk will be flatter and the white will be much more runny. An egg that spreads out when cracked isn’t necessarily bad, though, just older (and again, good for hard-boiled eggs). If it’s gone bad, you probably won’t even need to do the sniff test—even slightly rotten eggs will have a very strong, distinct smell you’ll notice right away.