When there is some food (like cheese or ham) that has roughly a week "use by" date, I assume that it's safe to eat it a day after it's "use by" date.

For other food that has approx. half year "use by" date (like olives in glass or pesto) I think it's safe to eat it for anything up to a month or so.

And for canned foods having years it should be safe to eat few months after "use by" date.

My thinking is that it's harder to pinpoint the exact date the further the date is in the future. I would even expect that "use by" dates are something around the half time the food is still actually edible.

Am I correct in this line of thinking? Do you know of any reliable resources on this? I couldn't find anything.

  • And also a recent questionon the date terminology, though this of course varies with country and language.
    – Chris H
    Commented Dec 5, 2016 at 22:44

1 Answer 1


"Use by" dates are pretty imprecise to start with. They're designed to be conservative, and they have a huge amount of leeway.

To the degree that they mean anything at all, I'd say that their precision is proportional to their duration. They might be conservative by, say, a factor of 2: eggs that are good for "1 week" are likely to be good for at least 2, and a box of cake mix good for "6 months" will be good for at least a year. And so on.

The fudge factor may well be closer to 4, or even 10. I've certainly kept a lot of things much, much longer than the expected dates. The only things for which expiration dates even come close is meat and fish, followed by milk. Those are things that "go bad" in obvious and unpleasant ways. Everything else just kinda gradually degrades, rather than suddenly becoming toxic.

  • I do agree. I hoped that there would be some reliable source beyond common sense. Commented Dec 6, 2016 at 8:59
  • There are too many variables for real precision. Common sense, and your nose, are really the best guides. Of course, the best diet generally involves lots of foods that spoil very quickly and should be eaten within days, or ideally the same day. There's nothing wrong with preservation, per se, but the processing that goes into it tends to concentrate calories and often removing the most nutritious parts. Still, any good pantry has a lot of things that you can keep on hand for a long time. Just use it judiciously. Commented Dec 6, 2016 at 15:48

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