How to Read Batch Codes

A cosmetic batch code (also called a lot number) is a short string of letters and digits that the manufacturer uses to trace a production run. It is not a public expiry date, but for most brands it encodes enough information to work out when the product was made.

Where to find it

Look on the bottom of bottles and jars, on the crimped end of tubes, on the base of lipsticks and compacts, or printed on the outer box. It is usually stamped, laser-etched or embossed rather than printed in color. Don't confuse it with the barcode (EAN/UPC), the shade number or the product reference code.

How brands encode dates

Every manufacturer uses its own format. Common patterns include a letter for the year plus digits for the month, a Julian day number (the day of the year, 1–365) combined with a year digit, or a factory code followed by the production week. Because the same characters mean different things for different brands, always pick the brand first and then decode the code.

From production date to freshness

In the EU, products with a minimum durability of 30 months or less must carry a "best before" date. Products that last longer instead show a Period After Opening (PAO) symbol, an open jar with a number such as 12M. In the US, the FDA does not require expiration dates on cosmetics. That is why the production date decoded from a batch code is often the most reliable way to judge an unopened product's age.

As a rule of thumb, most unopened cosmetics stay in good condition for around 30–36 months after production when stored properly. Once opened, follow the PAO symbol.