When shopping for eggs, most people glance at the date stamped on the carton, assume it’s the expiration date, and toss it into their cart without a second thought. But after spending years working in grocery stores, I’ve seen firsthand how often this little detail is overlooked — and how much confusion it causes.

What many don’t realize is that the date on an egg carton isn’t always a traditional expiration date. In the U.S., cartons often have a “pack date,” which tells you the exact day the eggs were placed into the carton. This number is a three-digit Julian date — for example, 001 means January 1st, while 365 stands for December 31st. It’s not meant to scare you into throwing eggs away too soon, but to let you know just how fresh they are.

Then there’s the “sell by” or “best by” date, which is where things get trickier. Eggs are generally safe to eat for several weeks after that date, especially if they’ve been properly refrigerated. In fact, freshness can often be tested at home — place an egg in a bowl of water. If it sinks, it’s still good. If it floats, it’s likely time to toss it.

The bottom line? Don’t just blindly trust the printed date. Learn to read those numbers carefully and use your judgment. Not only can you avoid wasting perfectly good eggs, but you’ll also become a savvier shopper — one who knows the small grocery store secrets that most people miss.