Online to OtB rating conversions

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Wadih Khoury
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Online to OtB rating conversions

Post by Wadih Khoury » Sun May 16, 2021 1:04 pm

Since the topic often crops up in this forum and everywhere, I wanted to share this website which attempts to convert ratings between chess.com, lichess, FIDE and USCF.

The website looks more serious than the various posts found on the net, though the pool size studied is not mentioned and standard deviation is not provided for all conversions.
I personally feel that it over-rates players when converting lichess to otb, but that is my gut feeling versus at least a semblance of scientific method.

The page is here: https://chessgoals.com/rating-comparison/

And the methodology here: https://chessgoals.com/rating-comparison-explained/


Worth noting that the standard deviation is often quite big and raises questions as to why. And also whether it is even meaningful to attempt conversion (after all, if you have 68% chance of being correct within a 300 point range, that does not sound very accurate)

Just yesterday I looked at some adult players ( to remove the effect of junior progression) and found a 2100 FIDE player with a 2400 lichess rapid rating, when I also found a 2450 Fide with a similar lichess rating. Both with lots of games played. Is the stronger player playing more casually online? Or is the lower rated player finding online play easier? Or is it a question of time controls preferences?

Kevin Thurlow
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Re: Online to OtB rating conversions

Post by Kevin Thurlow » Sun May 16, 2021 5:31 pm

I'm not sure, different systems give different results. Looking at my data

Blitz

FIDE 2048
Lichess 2058 (68 games)
Chess.com 1872 (148 games)

RP

Lichess 2141 (205 G)
Chess.com 1771 (34 G)

Chess960

Lichess 1867 (65G)
Chess.com 1571 (? maybe 20)

I'm not sure that tells us anything useful, except it suggests that either I'm more comfortable with lichess or the calculations used are different. The inventor of the original BCF system (Otto Clarke) did say ratings/gradings shouldn't be taken too seriously anyway, as they're only a rough guide to performance. Some people will play better online, some will play better in real life - I'm probably in the latter camp as with the longer online games, I find myself doing sudoku whilst I'm waiting for the move to arrive. Maybe the dog barks more when I'm using chess.com.

However, the SD will be quite big - it's not like chemical analysis, where if you measure fat content on 10 samples of the same (well-mixed) packet of milk powder, you expect all the results to be very similar. At chess, X can be a piece up vs Y, then leave a queen en prise, so one move changes the result of the game, and the swing in rating is pretty dramatic.

Traditionally, USCF ratings were about FIDE + 100, but I don't know if that still applies.

Nick Burrows
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Re: Online to OtB rating conversions

Post by Nick Burrows » Sun May 16, 2021 6:06 pm

I'm approx 2050 ecf, 1950 Fide.

Lichess blitz 2200, rapid 2250
Chess.com 2050 blitz, 2100 rapid.

My friend who has similar otb ratings is 2300 blitz on lichess

Matt Fletcher
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Re: Online to OtB rating conversions

Post by Matt Fletcher » Mon May 17, 2021 11:58 am

Nick Burrows wrote:
Sun May 16, 2021 6:06 pm
I'm approx 2050 ecf, 1950 Fide.

Lichess blitz 2200, rapid 2250
Chess.com 2050 blitz, 2100 rapid.

My friend who has similar otb ratings is 2300 blitz on lichess
I’m similar ECF to you, but 2300 blitz / 2350 rapid on lichess (my chess.com blitz is 2100 but I haven’t played there much).

For what it’s worth, my observations on the analysis posted:

1) it’s better than some others I’ve seen at comparing online blitz ratings, because it clearly shows that lichess and chess.com ratings converge and cross over at the higher end; this is definitely something I’m sure from speaking to others is a feature of the distributions, there’s a huge difference between equivalent ratings at lower levels, but much less as you get higher up.

2) I’m not sure about blitz vs rapid conversions on lichess - I’m playing more 10+0 rapid recently, my opponents are typically 2200-2300 in rapid and rarely much over 2000 blitz. I think there’s a bigger gap at that level than the table suggests between the two (at least 100 points, possibly more). A friend agrees - he struggled for a long time to get 2300 blitz and reached 2400 rapid without any problem at all. And I think he’d admit that he’s a much better blitz than rapid player.

David Sedgwick
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Re: Online to OtB rating conversions

Post by David Sedgwick » Mon May 17, 2021 1:39 pm

You have to remember that neither Chess.com nor Lichess use the definitions of Rapid and Blitz given in the FIDE Laws.

Matt Fletcher
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Re: Online to OtB rating conversions

Post by Matt Fletcher » Mon May 17, 2021 7:24 pm

Matt Fletcher wrote:
Mon May 17, 2021 11:58 am
2) I’m not sure about blitz vs rapid conversions on lichess - I’m playing more 10+0 rapid recently, my opponents are typically 2200-2300 in rapid and rarely much over 2000 blitz. I think there’s a bigger gap at that level than the table suggests between the two (at least 100 points, possibly more). A friend agrees - he struggled for a long time to get 2300 blitz and reached 2400 rapid without any problem at all. And I think he’d admit that he’s a much better blitz than rapid player.
Just to follow up on this - I looked through my recent games where opponents had both rapid and blitz ratings. This is based on 32 games in total.

Rapid
Highest: 2436
Lowest: 2137
Average: 2266

Blitz
Highest: 2354
Lowest: 1824
Average: 2065

Highest differential was 400 points, lowest was 37 - no opponent’s blitz rating was higher than their rapid one. Average difference (as you can see from above) was 200 points.

Not a big sample, clearly, but it does seem to point to a fair difference in ratings, at least at my playing standard.

Matt Fletcher
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Re: Online to OtB rating conversions

Post by Matt Fletcher » Mon May 17, 2021 7:52 pm

Although... I then did the same for my last blitz opponents and got average blitz of 2336 vs average rapid of 2333 (with a range of +/-200). More detailed analysis needed I feel...

Neill Cooper
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Re: Online to OtB rating conversions

Post by Neill Cooper » Wed May 19, 2021 11:59 am

Looking at my secondary school players on average they are rated 200 higher on lichess than ECF. Some players are rated 400 to 500 points higher, very few are rated lower.

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