What dating information can be found on egg packaging?

Printed on the side of the carton is a date and a separate series of numbers. On my current egg carton, for example, the stamp reads, "Sell by March 13, 2009" on one row, and on the other row: "P 1946 048 6". The "048" is the key; it represents the Julian Date on which it was packed, "Julian Date" being a three-digit code that represents the number of the day of the year (e.g. January 1 = 001, January 2 = 002, etc.). Thus, 048 is Julian for February 18.
 
On a carton bearing the USDA grade shield, the “sell by” date may not exceed 45 days from the packing date. The date on my carton of eggs is well within that range. Use of either a “sell by” date or an expiration date is not federally required but may be required by state laws in the state where the eggs are marketed, and the amount of time from packing to “sell by” is less than 45 days in some areas. In any case, if eggs are dated in your area, it’s good to buy ones that have not reached their “sell by” or expiration date.
 
Sources(s):
University of Nebraska - Lincoln
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