Where is my batch code?
First of all, it is not a barcode! It is a much shorter code than barcode. Batch codes are mostly printed on the package with different font from the product specification. If the package is bottle, the code can be found at either the bottom or the side of the bottle. The video here can show you how to find batch codes on a stick, a bottle and a tube. The rule works in most cosmetics products. You can find batch codes in such places in your cosmetics products.
I don't get a reasonable result. Is my product genuine?
The calculator is able to convert batch code to a production date or expiration date. There isn't a common database for all the cosmetics products. So it cannot be used to check if your product is genuine. If you buy your product from a trustable source, you don't need to doubt. If you put in other code instead of the correct batch code, the calculator can get a wrong result. Or if the cosmetics company has changed their way to make batch code, the calculator cannot get a correct result either.
Can the calculator calculate more products?
I would like to add more brands to the calculator. But some companies don't open their way to make batch code. I can only convert a small amount of brands that I know. If you know how to convert a brand's batch code, please kindly inform me so I can add it to the calculator.