My feedback would be to try looking in the FAQs first, as it usually results in a faster answer.
That said, I'm feeling nice, so here: http://support.chess.com/Knowledgebase/Article/View/26/0/how-does-vacation-work--how-much-time-do-i-get
What did you search in the FAQs. I did a search for "Vacation Days" and that article I sent you was like 3rd or 4th on the list.
I did. I couldn't find the answer there. According to protocol, this is the next step.
You are aware of how it is calculated so perhaps there is an issue of the display. I have 90 days displayed like this: "I have 2 months 29 days vacation remaining!"
How many days in a month?
365.25/12 = 30.4375
30.4375 * 2 + 29 = 89.875 = 90