My Grandmother’s Simple Trick To Tell if Eggs Are About To Go Bad

My grandmother used all of the tricks when she cooked. She kept a drawer of toothpicks for testing the doneness of cakes; she poked and prodded pork chops until she “felt” like they were cooked; and she saved rendered bacon fat to cook anything and everything. 

One thing I very rarely saw her do was check packages for freshness dates. Maybe that’s because those dates didn’t start appearing until the 1950s, and as a seasoned cook, she likely didn’t see a need for them. However, she had other ways of testing ingredients for freshness.

One trick I remember her using the most was the floating egg freshness test: She would fill a glass with water, add an egg, and watch to see what happened. Turns out, she was onto something.

How To Test Eggs for Freshness

Whether you bought your eggs at the store or got them directly from a farm, you might want to know which of the bunch you need to use first. One of the easiest (and most fun) ways to do that is by using my grandmother’s trick: Simply fill a cup with water and carefully add an egg.

If the egg sinks to the bottom, it’s fresh. If it sits on the bottom but stands up it’s “fresh-ish,” or a couple of weeks old and should therefore be cooked soon. If your egg floats to the top, it’s old, but don’t let the test trick you. The egg may still be edible. Inspect the egg for cracks first—if it is cracked and floats in the water, it’s best to toss it, as it may harbor bacteria.

If you crack the floating egg open and it looks and smells ok, it’s probably fine to use, though you may want to cook it fully (use it in a baking recipe, for example) rather than using it to make a sunny side-up egg.

Why the Freshest Egg Sinks

Egg shells are porous. That means what’s inside can slowly evaporate over time. As an egg ages, it starts to lose moisture through those tiny pores. An air pocket takes up that empty space. As the egg ages and continues to lose moisture, the air pocket gets larger. This makes the egg less dense and more buoyant, which will eventually cause it to float.

How To Buy the Freshest Eggs

The first step to getting good eggs is knowing what to look for at the store. If you’re a smart shopper, you should never randomly pick up a carton, assume everything is good, and drop it in your cart. Instead, use the USDA recommendation of purchasing eggs before their sell-by or expiration date, which is handily printed directly on the packaging. 

Next, open the carton and inspect the eggs. Look for cracks, stickiness, or discoloration. If the eggs show any of those signs, it could be an indication of damage or that bacteria and/or mold are present, says Jen Bruning, MS, RDN, Spokesperson for the Academy of Nutrition and Dietetics. 

You can also give the eggs a sniff. If they smell awful, they’re not safe to eat (makes sense). If your carton of eggs passes these tests, bring it home, refrigerate them immediately, and use them within three to five weeks of that sell-by/expiration date.

If you want to know more about the age of your eggs, look for the USDA grade shield on the carton. The shield includes a three digit code that specifies the day of the year that the eggs were washed, graded, and placed in the carton. It begins with January 1 as “001” and continues through December 31st as “365.”