# Chess Ratings - How They Work "by Eric"

• 7 years ago · Quote · #1

Like it or not, we ALL have a chess rating. You may not care at all about you rating, or you may be whining every time it goes down in the slightest. You might be someone who plays a game a year, or someone who plays 1,000 a day. Still, there is a number out there that represents how well you play chess. Well, that's the theory, anyway.

To understand chess ratings you have to understand two things:

#1 - that you have a TRUE rating that perfectly represents your strength of play, and

#2 - that that TRUE rating will never be known and so we have to use statitics to get as close as possible to the truth. I'm writing this article in response to many people who ask about ratings and need a simple explanation of how they work. (I only know about all this because of a recent super-in-depth statistics course I took and my research in building Chess.com!)

There are two main rating systems, and each one has its merits.

The Elo System (used by the United States Chess Federation, FIDE, and many other online chess sites) is popular for two reason - it has been around for a long time, and it is simple. The idea is this: given two chess players of different strengths, we should be able to calculate the % chance that the better player will win the game. For example, Garry Kasparov has ~100% chance of beating my 4-year-old daughter. But he may only have a ~60% chance of beating another Grandmaster. So when playing that other Grandmaster, if he wins 6 games out of 10, his rating would stay the same. If he won 7 or more, it would go up, and 5 of less, his rating would go down. Basically, the wider the spread of the ratings, the higher percentage of games the higher rated player is expected to win. So to calculate a person's rating after playing a few games you calculate the average ratings of his opponents, and then how many games he was expected to win, and then plug it into a formula that spits out the new rating. Simple enough. Well, it turns out, that is maybe TOO simple.

I wish there was some simple analogy to explain all this, but there isn't. It all comes back to this: you have a theoretically exact chess rating at any given moment, but we don't know what that is and so we have to use math to estimate what it is. There are really smart people out there who work on this stuff for a living, and at the end of it all we get to put their proven methods into our code so that we can all enjoy knowing what little numbers next to our name we deserve.

Submitted by erik on Fri, 08/24/2007 at 7:56am.

• 7 years ago · Quote · #2

Thanks for copy and pasting?

• 7 years ago · Quote · #3

• 21 months ago · Quote · #4

Chess Rating app. for the chess players who want to calculate their score against single player or multiple players and keep record of it. The Chess Rating app. uses the Glicko rating system, which is developed by Professor Mark E. Glickman
Main Features:
•Easy and intuitive interface.
•Option to type in your and opponent's Name, Rating, RD and Score OR browse it in one click (the app. downloads the current data released by Australian Chess Federation (ACF) and presents it to you - this option is good for players who use ACF ratings).
•The app. updates the ratings soon after ACF releases it (with your consent) - But if you don't play in Australia, you don't require ACF rating, you can use your information (feed info. in the app.) to calculate the rating.
•Create calculations against single or multiple (upto 12) players - as of now.
•The calculations can be stored locally in a database as profiles to access later.
•Calculations can be edited and deleted as and when you need to.
•App. uses the saved profiles to show your progress in an interactive graph. When you tap on red dots on graph, it shows you the players’ information.

• 10 months ago · Quote · #5

Why you go down in rating when you lose a game I still do not understand. If you loose does this mean you became more worse? I step out a tournement sometimes when I see I cant go thru anymore... And rating Goes down. So what does my rating say of me at that moment? Better yet... What does opponents must think then? So I think rating does not say anything About your opponent. ;-).