Observe the product code on the top flap of the cereal box to determine its location. How do you read the expiration date on cereal? However, cereals, including Rice Krispies, will almost surely lose their freshness beyond that date, and this is not an exception. In contrast to the milk with which they are so frequently served, most cereals will keep for months or even years after their expiry or best before dates. What should you do? The key is to recognize that the expiry date is displayed in the ″MMDDY″ format, in which the first two digits indicate the month, the next two digits represent the day of the month, and the last number represents the year otherwise, the date will appear as ″MMDDY.″ How long do Rice Krispies last? The expiration code on your Kellogg’s brand goods is confusing.