The key rules first
- An EU/UK use by date is a safety limit — don’t eat, cook, or freeze the food after it, even if it looks and smells fine.
- Best before (EU/UK) and most US date labels indicate quality, not safety.
- Infant formula is the exception in the US: its use-by date should always be respected.
- Once a package is opened, the after-opening instruction takes over from the printed date.
Why one word can’t cover both
A quality date answers “when will this stop being at its best?” A safety date answers “when might this become hazardous even if it seems fine?” The failure modes are different: quality failures (staling, separation, freezer burn) are visible and harmless; safety failures (listeria in a ready-to-eat food, toxins in mishandled leftovers) are invisible. That is why this site labels every duration as one of four types — safety guidance, best quality, package date, or personal plan — and never collapses them into one “expiry date.”
Worked example
A UK yogurt marked “use by 24 Aug” must be eaten or frozen by Aug 24. A US yogurt marked “best if used by 24 Aug” can still be fine after — check the after-opening guidance and storage conditions instead. Same wording style, different meaning: this is why every result on this site names its region.
Common mistakes
- Smelling food to override a use-by date.
- Reading US “sell by” as a home-safety deadline — it is stock-rotation information for the store.
- Assuming freezing “resets” a use-by date that has already passed.