From what I can tell it might be something like this:
Chess.com = USCF + 200 = FIDE + 300
That only applies to higher rated players. For a player rated below 1600 Chess.Com, it is VERY unclear where the correlation between rating systems "Is TRUE".
F.ex in OTB games I'm usually paired with players between (1400 - 1500) ELO. Here on Chess.com a low rating doesn't mean anything anymore. It did 10 years ago, when they correlated with USCF-rating very much. But those days are gone for the below 1600's.
As of right now, USCF Standard (unofficial) = 2105, FIDE Standard = 2007, chess.com blitz = roughly 2000.