The best way to test eggs for freshness

According to The Washington Post, Americans eat almost 300 eggs per person each year, but that familiarity doesn't make figuring out if your eggs are fresh any easier, especially since the yolk and white float out of sight inside each mostly-opaque shell. More confusingly, the sell-by date on your egg carton doesn't mean that after that date, the eggs are bad — they can stay fresh for four to five weeks after the sell-by date printed on the carton (via What's Cooking America). Luckily, it's actually very easy to tell if your eggs are fresh, and you don't even have to crack the shell to find out. 

If you don't want to waste an egg simply to test it for freshness, then the easiest way to tell if an egg is fresh without cracking it is to see if it floats. Fresh eggs will sink to the bottom of a bowl of cold water and lay on their side, less fresh eggs will fall to the bottom but remain upright, and spoiled eggs will float to the top. That's because as the eggs age, their shells become more permeable, meaning more air gets in. In an old egg, there's enough air inside the shell to make the egg float (via Southern Living). 

To be even more certain that your eggs are safe to eat, you can also try a sniff test. Spoiled eggs will have a sulphuric, foul odor that means they are no longer safe to eat, which can sometimes be detected through the shell of an uncracked egg. If you notice a rotten odor before or after cracking your egg, it's no longer safe to eat, and should be discarded. Also take note of the color of the egg white and yolk when you crack it. Any eggs with pink, iridescent, or greenish whites or yolk should be discarded (via Medical News Today).