There is 0 correlation. Its a completely different pool of players for one thing. Other than that many people simply dont try when playing online, since theres no motivation to win, or are multi-tasking.
FIDE rating vs. chess.com rating

i see.. thats true.. so, you can only gain fide rating on official tournaments..is it true? dont know much about that..

yes thats right. Not all tournaments will give you a FIDE rating though, some will only give you a national rating (depending on whose holding it)

thansk! one more question.. in your opinion.. this rating on chess..com...lets say online chess where you have 3 days per move.. can it be some kind of indicator on your FIDE rating...? take yourself as an example... is your FIDE rating higher or lower than one on chess.com?

Most people have FIDE ratings close to their Blitz/Live Standard ratings. The online ratings tend to be 200-300 points higher though.

There is 0 correlation. Its a completely different pool of players for one thing. Other than that many people simply dont try when playing online, since theres no motivation to win, or are multi-tasking.
+1
Not only are the ratings pools entirely different, so are the calculations. And USCF and FIDE will only rate games under tournament conditions.
It's beyond comparing apples to oranges. It's trying to compare apples to gophers.
The standard response, but not a useful one. He's asking if it's an indication. It clearly is, because we've seen enough threads with people posting FIDE vs chess.com ratings to come to a generalisation.
He didn't ask if it's an exact formula which is of course impossible.
Can anyone tell me how reliable rating on chess.com is, and is it similar with a official FIDE rating? maybe someone who has experience with this can tell me...thanks