Learn the different types of dates used for expiration codes. Determine if the code is using letters for months, the Julian calendar or a month, day and year code.
- Learn the terminology for food expiration codes
The best if used by date, which is also called the use-by date, means the product will deteriorate after this date but may still be edible. The expiration date means the item should be thrown away after this date. The sell-by or pull-by date tells grocers when to take the product from their shelves, but it may still be good for home usage. The guaranteed fresh date is used for perishable goods, which may still be edible. The pack date tells when the item was packed and appears most often on canned and boxed goods. It is also the date that usually comes in an encrypted code. To decipher the code, you have to know the dating system used.
- Check if there are any letters
First, look for any letters within the code. A letter signifies the month. January is "A," February is "B," March is "C," April is "D," May is "E," June is "F," July is "G," August is "H" and September is "X" because the letter "I" is usually omitted. October is "J," November is "K" and December is "L." If there is a letter, the numbers next to it indicate the day and year. The year may be at the end or beginning of the code.
- Check for the dates by month, day and year
The code may use the standard month (M), day (D) and year (Y) system. This system can be coded either YYMMDD or MMDDYY. Remember that the month digits can only be from 01 to 12 and that the day digits can only be between 01 and 31. The other date should be the year.
- Check for the Julian calendar
If the code doesn't use either of the previous codes, it's most likely using the Julian Calendar, which assigns a number for each day of the year from 1 to 365. The year will usually be listed with one or two numbers. In the Julian calendar, January is 001 to 031. February is 032 to 059. March is 060 to 090. April is 091 to 120. May is 121 to 151. June is 152 to 181. July is 182 to 212. August is 213 to 243. September is 244 to 273. October is 274 to 304. November is 305 to 334. December is 335 to 365.