How do ratings work on Chess.com?

Everyone on Chess.com has a rating. The purpose of this rating is to try to show the level of skill of each player, to better match you against other players of equal rating. 

You’ve probably noticed that after you win or lose a game, your rating doesn’t always go up or down by the same amount. What causes this difference? 

A few things can affect how much your rating changes after you play a game. Some things that can affect this are:

  1. The difference in rating between you and your opponent
  2. How confident we are of your rating
  3. How confident we are of your opponent’s rating

Number one is pretty straight forward. If you win against someone who has a much higher rating than you, your rating will go up by a higher amount than if you win against someone of your same rating, or of a lower rating. 

Similarly, if you lose against someone with a lower rating, your rating will go down more than if you lost to someone with a higher rating. 

Numbers two and three on the list are a bit more complicated. It might sound strange, but confidence in the rating is the main reason for big changes in your rating after a game. 

Chess.com uses the Glicko rating system, and part of this system is a number called a ‘rating deviation’ or RD, which measures how sure we are of what your rating is. The lower the number, the more sure we are of what your rating is. You can see this number on your stats page for each game type. 

The above example is from my blitz stats page. It’s a pretty low number because I play blitz regularly. Because of this, when I win or lose a blitz game, my rating changes by a small amount, usually 2-10 points depending on how strong my opponent is. 

My bullet RD however, is much higher, because I never play bullet. If I were to play a bullet game my rating would probably change by between 100 and 200 points. Because I never play bullet, chess.com’s ratings system has no way to tell how good I am at it. 

If you don’t play any games for a while, your RD will go up, and the next game you play might change your rating by a lot. This is because chess.com hasn’t seen any games from you in a while, and there is no way to tell whether you’ve been practicing and getting better other places, or if you haven’t been playing at all. 

The same applies to your opponents as well. If you lose to someone who is several hundred rating points lower than you, but with a very high RD, your rating won’t change much, because we can’t be sure that is their actual rating.

If you’re curious about more of the inner workings of the rating system, check the articles here and here! 

Our advice to you, though, is to just play games and have fun, and let the rating sort itself out!  

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