Egg cartons can seem confusing, especially when they contain several dates and numbers. The three-digit code found on many U.S. cartons is usually a **pack date**, not an expiration date. It shows the day of the year when the eggs were processed and packaged, with 001 representing January 1 and 365 representing December 31 in a non-leap year. For example, 032 means February 1, while 198 represents July 17. The code can help you compare cartons and use older eggs first, but it does not determine whether an egg is safe to eat.

You may also see a code beginning with **P**, which identifies the processing or grading facility. Other labels, such as “Sell By,” “Best By,” or “Best Before,” serve different purposes and should not automatically be treated as expiration dates. A sell-by date mainly helps stores manage inventory, while best-by dates are more related to quality. Proper refrigeration remains essential, and USDA guidance says raw shell eggs generally keep for about three to five weeks when refrigerated.

Freshness and safety are not the same thing. An egg can look and smell normal while still carrying harmful bacteria such as *Salmonella*. That is why the popular water **float test** cannot prove whether an egg is safe. Floating usually indicates that an egg has developed a larger air cell as it ages, not that it contains bacteria. As the article explains, “floating does not tell you whether an egg contains Salmonella or another harmful microorganism.”

For safer storage, keep eggs refrigerated at **40°F or below**, preferably on an interior refrigerator shelf and in their original carton. Keep shells clean and uncracked, wash hands and surfaces after handling raw eggs, and refrigerate cooked egg dishes promptly. FDA guidance recommends cooking eggs until the whites and yolks are firm. Cooked egg dishes generally keep about three to four days in the refrigerator, while hard-cooked eggs can last about one week.
The main lesson is simple: use carton codes as helpful information, but do not rely on them alone. “Buy them cold. Keep them cold. Protect the shells. Avoid cross-contamination. Cook them appropriately. Refrigerate leftovers promptly.” If an egg has a badly cracked shell, obvious contamination, a rotten odor, or has been kept at unsafe temperatures for too long, it is safer to throw it away.