TL;DR
When a package says to use it within a few days after opening, write the actual date on it immediately. No more guessing later.
How to do it
- When you open the package, read the small note: for example, "use within 3 days after opening".
- Calculate the exact date.
- Write it on the lid, jar, carton, or wrapper with a waterproof marker, chalk marker, or small label.
- Put the item back so the date is visible when you open the fridge.
Ingredients
- Waterproof marker, chalk marker, or small label
- Optional: tape for dark or damp packaging
- 10 seconds of attention when opening the item
Why it helps
Many foods have two dates: the regular best-before date and the much more relevant deadline after opening. That second deadline is easy to forget because it is usually hidden in tiny print. A visible date on the package turns it into an instant decision.
Good to know
The written date is a guide, not a safety guarantee. If food smells wrong, shows mould, has a swollen package, or was not kept cold properly, trust the condition of the food over your note. When in doubt, throw it out.