USCF, FIDE, chess.com and so on are all different groups of players (player pools) and so they aren't really comparable in that x-rating means y-rating somewhere else. Closest we got are statistical similarities based on players in both groups, but there is no "conversion."
With this said, if I were to estimate then chess.com 1900-ish level is probably about 1800 level USCF at same time control (or a few hundred points lower usually) and FIDE is close or even a little tougher than that, so maybe 1900 chess.com is about 1700 FIDE.
These are just my estimates though - again, there isn't a "conversion" formula to apply.
So I just reached 1900 bullet and rapid and 1869 blitz on chess.com and want to start playing in OTB tournaments...anyone have a general conversion for what I could expect my FIDE/USCF ratings to be about?