Yeah, I came across such charts but I have no idea how many percentage points the humidity here fluctuates indoors throughout the year, so I can't hope to calculate correctly.
I was hoping for a general "rule of thumb that should work in most situations"
Edit:
Looking this up further, it seems there's a distinction between "Moisture Content" in percentage terms, of the wood, and "Relative Humidity" -- a distinction that I wasn't making as I first tried to calculate.
https://www.thisiscarpentry.com/2010...wood-movement/
Okay, but I still have no idea how to even measure moisture content, nor do I have a year to do so with a given piece of wood before I start building...
Nor does Google seem to understand any of my conceived ways of wording the question "how much does furniture typically change in moisture content over the course of a year?"
I'm just amazed that every article I come across just assumes you have all of this data and can therefore calculate everything and put a plan into action, lol