Lichess rating -> chess.com rating -> USCF rating -> FIDE rating

I know the connection between the ratings is not 100% accurate, but can someone explain to me how I am 874 USCF rating yet 1409 on chess.com (rapid rating, mostly 10min)? btw these ratings are at the time of writing.
I know there is going to be some difference, but I am really confused on how there is a 600+ point difference.

Ratings are relative to the player pool and their ratings. Everyone uses their own system so the ratings are not comparable.

chessgoals.com/rating-comparison/#Rating_Comparisons

You have deviated by a lot on the expected variance range. One possible reason for that is likely due to the fact that your USCF rating may be outdated and may need to participate in more rated games to have it updated.

Imagine chess as music with notations. Do you really want to try to compare a guitar with a piano? Or classical music with rock. Both are used to play music. Both sites are used to play chess. If a guitar and a piano are not the same, then neither can the rating systems from different sites. They might have numbers but don't mean the same thing.

A chess rating system is also like using languages from different countries. All have letters to build words, but do not form the same words to mean the same thing.

An approved rating translator is a tool that chess will probably use when AI's control the rating systems.

Even estimated next move probabilities are different from site to site.
en.wikibooks.org/wiki/Chess_Opening_Theory/1._e4#:~:text=Estimated%20next%20move%20popularity

@Toscani said in #4:
> Imagine chess as music with notations. Do you really want to try to compare a guitar with a piano? Or classical music with rock. Both are used to play music. Both sites are used to play chess. If a guitar and a piano are not the same, then neither can the rating systems from different sites. They might have numbers but don't mean the same thing.

That's not a very good analogy, comparing rating systems is more like comparing different type of pianos which most certainly can be done.

A guitar vs a piano. Not a piano vs another piano.

sorry but the math formulas for one rating system is not the same as other rating systems. So it is a very good comparison. Comparing music instruments that can play the same song, but with different tools.

the problem is it's not going to sound the same. So the ratings even though they have numbers 1800 vs 1800 do not have the same sound. The ratings were not created by the same players.

You really have to start thinking outside the box. The rating numbers may look the same, but they are not the same.

A 100% in grade one is not 100% in university. Yet it's still 100% rating score. You cannot compare them. that's it. Even if others think they can be, I beleive they cannot be. Just by this last example in percentage form is enough to understand.

From my experience USCF is typically 500 points lower than chess.com. You're not out of the ordinary. I'm about 1000 rated and 1500 on cc.

Basic thing is as sais above: rating are relative. They do not measure you chess skill but how well you win other players that particular pool. And what sort of skill level maps to what sort of rating is then dependent on whole lotta things
- how initial rating is formed. USCF/Elo use initilization based some amount of games while glicko-x used some pre-determined value with high rating deviation estimate (chess.com 1200 and lichess 1500)
- how strong rating pool is compared to you. Chess.com/lichess rapid pools are lot weaker than blitz pool. so that alone explains abotu 200-300 points of difference
- and to a minor degree the adaptation algorithm. Glicko type algorithms do not inherently produce different number but there is a small difference due to differerence id convergence speed. They all produce number where 200 point difference means that in long match stronger player win 3/4 of the points and weaker wins the rest.

So in short actual numeric value is meaningless. it only to find you a matching opponent and all the systems work well enough in this respect

its very simple.
the ELO (and related rating systems like Glicko-2 used by lichess) are based your win/loss performance against other players IN THE SAME POOL. If the players are stronger in one pool than in another, then your rating in the stronger pool will be lower (even if an identical ratings system is being used).

FIDE is a group of players that are pretty serious about chess (they joined FIDE and play in a club), where as anyone and their uncle can play on lichess by signing up. Its not surprising the average strength of players on lichess are lower than on FIDE. On top of that FIDE uses the ELO ratings system and lichess uses Glicko-2 which is slightly different.

All ratings are specific to a pool. Those based on higher levels of activity will prove more accurate. Hence, the replacement of Elo’s original formula with Mark Glickman’s modifications (“Glicko”).

As for different pools, it is well-known that Lichess ratings tend to be higher than ratings on chessdotcom and ICC. USCF ratings tend to be slightly higher than FIDE.

Strangely, USCF OTB tend to be close to chessdotcom blitz.