You might be surprised to learn that some egg cartons tell you exactly what day the eggs were packed—a piece of information that’s a lot more specific than a sell- or use-by date. About one-third of the eggs in the U.S. are packed under the USDA’s voluntary grading service. If the eggs in your market were graded by a USDA inspector, the carton will display a USDA grade shield (shown here), and a three-digit code that reveals the packing date will be stamped somewhere on the carton, usually on the short side near the expiration date. The code is actually a Julian date, meaning it represents a day of the year, not a day of a month. So, a carton marked “001” means it was packed on January 1; “365” means it was packed on December 31. To find the freshest eggs in your store, look for the packing date that has the highest number (with the exception of the transition from December to January).

Don’t confuse the packing date with the packing plant number, which is always preceded by the letter “P.” If the carton doesn’t have a USDA shield, then it was packed under local regulations, which vary from state to state, and it may or may not carry a packing date.