What a batch code is
A batch code (you’ll also see it called a lot number or production code) is a short run of letters and numbers that marks which production run a product came from. Brands use it for quality control and recalls. Often it also holds the manufacture date, written as a letter for the month, a digit for the year, a week number, or sometimes a plain date.
There’s no worldwide standard. Each brand, and sometimes each factory, has its own system. That’s why the app asks for the brand first.
Where to find it
- The bottom of bottles, jars and compacts. Often stamped, embossed or laser-etched.
- The crimped end of tubes. Check the sealed edge for a small printed or stamped code.
- The outer box. Usually near the barcode, but boxes get thrown away, so check the product too.
- Palettes and sticks. Sometimes on a small sticker on the back.
Can’t see it? Tilt the pack under a light. Etched codes show up much better at an angle.
How the date is hidden in the code
Typical systems use a letter for the month, a digit for the year, and a number for the week or day. Others print an ordinary date. The same characters can mean different things at different brands, so a code only makes sense next to its brand.
In the app you choose the brand and type the code. It works out the manufacture date and adds the usual shelf life for that kind of product.
Batch code vs PAO symbol
These two markings answer different questions.
| Marking | What it tells you | Use it for |
|---|---|---|
| Batch code | When the product was manufactured | Unopened products, or checking how old a product already is |
| PAO symbol (open jar, e.g. 12M) | How many months it stays good after opening | Opened products |
On a sealed product, count from the manufacture date. Once you open it, the PAO is usually the number that matters, even if the sealed shelf life is longer.
Typical shelf life
It depends on the product and the formula. As a rough guide, many sealed makeup and skincare products last about two to three years from manufacture, and fragrance often lasts longer. Treat these as estimates. Heat, sunlight and humidity shorten them.
When to throw it out
- A new or sharp smell, especially a sour one.
- Separation, clumps or a changed texture.
- A shift in color.
- Stinging, irritation or breakouts after you use it.
If you notice any of these, stop using it, whatever the date says.
Ready to check? Pick the brand, type the code, and you’ll have the date in seconds. Cosmetic Checker is on the App Store or Google Play.