How do you tell the Pappy year of release?

I have some unopened bottles from a few years ago—20 year and 15, maybe some 10. How do I tell release year?

google ‘pappy lot number’

Here’s one I’ve used

So one of my bottles of 20 year is 2012, the other a Japanese market unknown year


That the 15 year I sent you years ago? Hopefully that one got drank!

got a friend who pounds the stuff.