Best estimate of rating?

Not that post #4 is so wrong, but it's been surveyed, and on average chess.com blitz is closest to USCF rating. Yes it's different players, time control, seriousness, etc. but it is the same game. It makes sense that there is a loose correlation.
I don't play much here anymore but my USCF rating stands at 1610 and my ratings here are around 1700 and tactics rating hovers around 1900 to give you an example of the improbability of a reliable conversion ability between your online ratings and a USCF/FIDE rating estimate. You just got to go compete and see what rating you get if you want to know!

i feel the longer term game you play, such as the one we are playing now, is the most accurate. it is the way the game was meant to be played. shorter term games make you rush to control time.
My blitz rating: 1357
My USCF otb regular rating: 1636
?????
It's only on average. Some people are very good at blitz, some people suck.
I would ask whether your USCF rating has been the same over the last few tournaments, and whether you've played those tournaments recently.
i feel the longer [the] game you play . . . the [more] accurate [it is]
Rating doesn't measure playing strength though, it measures results. It may sound the same, but results are based on the strength of the opponents. If only all the noobs play blitz on a website, then even a noob will be rated 1500 (for example). If only GMs play blitz on a website, then even very good players could be rated 1000.