Where it's printed
You're looking for four digits, then a couple of letters, like 9322MM. One letter in front is allowed, and the app skips it. Where the mark sits varies by product; the batch code guide covers where to look.
How the code is built
Ignore one leading letter if there is one. After it comes a single digit, the last digit of the year, and then three digits for the day of the year, counted from 001 on 1 January. Whatever comes after those four characters is ignored.
Worked example
9322MM. The 9 is 2019 and 322 is the 322nd day of the year, which is 18 November 2019. The app uses 60 months for Shiseido, which puts the best before date at November 2024. In November 2026 that is already past.
A code with a day in it gets an exact date rather than only a month.
Variants and edge cases
The app handles the variants and edge cases for you. Some codes the rule can't date; the app says so instead of guessing.
Shelf life and the PAO symbol
Here the sources disagree. Shiseido's US and Japan sites say about three years for sealed products, and its Canadian site says about five. The app uses 60 months, the longer figure, so the best before date it gives is generous. If you're unsure, count from the shorter one.
After opening, follow the PAO symbol on the pack, the open jar with a number of months beside it.
Cosmetic Checker is independent and isn’t affiliated with Shiseido.