Answers.Body: <p>I did this graph based on 731,000 games played on the free internet chess server by players with rating above 2000 during the last 13 years with <strong>non-blitz time controls</strong>.
  The <strong>average length is 79 half moves</strong>, the <strong>median is 70</strong> and the <strong>mode is 51.</strong> There are also a lot of very short games due to people resigning early.</p>
  <p><img src="https://i.sstatic.net/vcJAF.png" alt="Distribution of chess game length" /></p>
  <p><strong>Update:</strong> As it turns out, the above curve can be very well approximated by a log-normal distribution. That is the logarithm of the games lengths are normally distributed. We can then consider the expected game length remaining given how many moves have already been played, which may be interesting for chess engines. It looks like this:</p>
  <p><img src="https://i.sstatic.net/rnzQt.png" alt="enter image description here" /></p>
  <p>If you want to use it for figuring out how to use your time(*), the function can be very well approximated by the following expression. (Again remember, that the result is in half moves.).</p>
  <p><code>59.3 + (72830 - 2330 k)/(2644 + k (10 + k))</code></p>
  <p>(*)Though you would probably want to take other factors into consideration as well.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-04-24T19:16:05.907Z
Answers.Text: How much better does it fit a log normal as opposed to a Weibull, Gamma, or Beta distribution?
Answers.UserDisplayName: StudentofEuler2718
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Answers.CreationDate: 2020-03-08T22:31:06.647Z
Answers.Text: Do you happen to have this data on hand? I would like to have a look at it myself.
Answers.UserDisplayName: Ivar Eriksson
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Answers.CreationDate: 2024-11-28T05:10:51.410Z
Answers.Text: How do rating 2 variables affect those curves?  This could be made a surface with average of game pair of ratings (assuming not large differential).  or higher dimension statistical problem is using all the ratings.  I  think lichess data from patzer to stratosphere.  I am asking because of A0 and LC0 zero-knowledge batch to good engine play trajectories, whether they sample outcomes at different phases of the games as they become better, (but also reduce their exploration intensity, by RL dilemna).
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Answers.LastActivityDate: 2018-06-08T11:21:26.980Z
Answers.LastEditDate: 2020-06-17T09:59:59.497Z
Answers.UserDisplayName: Thomas Ahle
Answers.Body: <p>We can make a small analysis from a theoretical point of view:</p>
  
  <ul>
  <li>Let us call 'n' the number of pieces on the board.</li>
  <li>In a match between players of similar strength, it is expected to find ~n/2 pieces for each side.</li>
  <li>When it is White's turn to move, they have 64-n/2 available squares, n/2 are occupied by rival pieces.
  That is, fc=(n/2)/ (64-n/2) is the fraction of moves that result in a piece capture</li>
  <li><p>The same number applies for Black.</p></li>
  <li><p>n=32 --> fc~1/3, at the end of the opening, with pieces fully developed</p></li>
  <li>n=22 --> fc~1/5, middle-game</li>
  <li>n=16 --> fc~1/7, end-game</li>
  </ul>
  
  <p>So, on average, we can expect that each player loses 1 piece every 5 moves approximately.
  It takes ~8*5=40 moves to reach a population of 8 pieces vs 8 pieces.
  After 40 moves, with both "armies" reduced to its half, there is a reasonable expectation that one of them has already lost its king, and so the match is ended.</p>
  
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Answers.UserDisplayName: Diedrsch
Answers.Body: <p>The average length of chess games depends highly on the reflection time schedule since decisive errors happen very often under time pressure. Cf. <a href="https://ingram-braun.net/public/research/parlour-games/article/statistics-length-chessbase/" rel="nofollow noreferrer">https://ingram-braun.net/public/research/parlour-games/article/statistics-length-chessbase/</a></p>
  
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Answers.CreationDate: 2017-08-05T06:50:58.660Z
Answers.LastActivityDate: 2017-08-05T06:50:58.660Z
Answers.UserDisplayName: Archäopath
Answers.Body: <p>Sahovski Informator publishes approximately 700 of the Best or Most Interesting games of the preceding several months, played by Grandmasters around the world.  I have found the average number of moves in several volumes to converge at between 43 and 44 moves per game.  This is, of course, for Grandmasters in tournaments or matches, so they are not giving up easily.  Also, interestingly, the number of moves is slowly increasing as time goes forward, indicating perhaps that fewer mistakes are being made, so that games are taking longer.<br>
  Also, there is a small variation in length based on the openings - e4-e5; d4-d5; d4-nf6; e4-c5 etc, but it doesn't seem significant.  </p>
  
Answers.ContentLicense: CC BY-SA 3.0
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Answers.LastActivityDate: 2015-01-25T06:42:41.880Z
Answers.UserDisplayName: Robert Barncord
Answers.Body: <p><strong>EDIT:</strong> I opened Mega Database 2012 and found there were 515539 games ranging from the 1400s to 2011. As I couldn't find an efficient way to parse the data, I just used the median move value (I hope it's normally distributed. It's probably not though as the largest number of moves was 277... oh well). The median value was 37 moves, but I'm sure that it's a right-skewed distribution given the max value. If I had to hazard a guess to the average value, I'd put it slightly greater than 40 :)</p>
  
  <p>In addition, keep in mind that these are all <em>recorded</em> games. This means that their origin can be from tournaments, matches, or even online competitions. Indeed, the 277 move game was played in a tournament on the Internet Chess Club.</p>
  
  <hr>
  
  <p>Oddly enough, I found that the average length of a game (played by humans) is roughly 40 moves. Based on the <a href="http://www.chessgames.com/chessstats.html">statistics</a> provided by the Chessgames database (685,801) games, the average number of moves is 40.04. Chessgames tends to only include player games of a high caliber, so this doesn't really take into account amateur tournaments. As these games are played by humans, few of them tend to end in checkmate but rather a draw by mutual agreement or a resignation in a lost position.</p>
  
  <p>This may not be the best source, but I've played in over 320 tournaments in my life and many of these games are imported into my personal database. The average number of moves per game is around 38.</p>
  
  <p>I do not have access to my Mega Database 2012 (a database provided by Chessbase) at the moment, but I will post the average number of moves of approximately 5 million historical games when I open it.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-04-24T15:02:41.823Z
Answers.Text: Relevant? [Why does FIDE classical chess have a time limit for the first 40 moves?](https://chess.stackexchange.com/a/34890)
Answers.UserDisplayName: BCLC
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Answers.CreationDate: 2013-06-26T20:32:36.807Z
Answers.LastActivityDate: 2013-06-27T01:54:13.690Z
Answers.LastEditDate: 2013-06-27T01:54:13.690Z
Answers.UserDisplayName: Andrew Ng
Body: <p>I hope this is an appropriate question for this site as I've been wanting a reputable answer. Of course the length of games can vary wildly, but what is the expected number of moves until either a checkmate or trivial draw position is reached? Preferably the answer will be backed by some evidence and is not just "40 moves" like every other internet source. </p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-08-05T02:01:06.593Z
Comments.Text: I have a friend who fights on in every losing position, and he often records 60 moves before time pressure forces him to stop taking notation.
Comments.UserDisplayName: Fred Knight
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2013-06-26T19:44:07.027Z
Comments.Text: You can't really get this information from existing games, since they tend to end (by resignation or agreed draw) long before mate or trivial draw.
Comments.UserDisplayName: dfan
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2013-06-26T19:47:46.420Z
Comments.Text: @dfan That is true. Perhaps a sample of fast games or those played by engines would be suitable.
Comments.UserDisplayName: Zong
Tags: <statistics><database><game-length>
Title: What is the average length of a game of chess?
ThreadText: # What is the average length of a game of chess?
  
  (Asked by: username_0 on 2013-06-26)
  
  I hope this is an appropriate question for this site as I've been wanting a reputable answer. Of course the length of games can vary wildly, but what is the expected number of moves until either a checkmate or trivial draw position is reached? Preferably the answer will be backed by some evidence and is not just "40 moves" like every other internet source.
  
  **Tags:** statistics, database, game-length
  
  > **Comments:**
  > **username_2**: You can't really get this information from existing games, since they tend to end (by resignation or agreed draw) long before mate or trivial draw.  
  > **username_0**: @username_2 That is true. Perhaps a sample of fast games or those played by engines would be suitable.  
  > **username_1**: I have a friend who fights on in every losing position, and he often records 60 moves before time pressure forces him to stop taking notation.  
  
  ---
  
  ## 5 answers
  
  ### Answer by username_10 on 2013-06-26. Score: 44 | Accepted answer
  
  **EDIT:** I opened Mega Database 2012 and found there were 515539 games ranging from the 1400s to 2011. As I couldn't find an efficient way to parse the data, I just used the median move value (I hope it's normally distributed. It's probably not though as the largest number of moves was 277... oh well). The median value was 37 moves, but I'm sure that it's a right-skewed distribution given the max value. If I had to hazard a guess to the average value, I'd put it slightly greater than 40 :)
  
  In addition, keep in mind that these are all *recorded* games. This means that their origin can be from tournaments, matches, or even online competitions. Indeed, the 277 move game was played in a tournament on the Internet Chess Club.
  
  ---
  
  Oddly enough, I found that the average length of a game (played by humans) is roughly 40 moves. Based on the [statistics](http://www.chessgames.com/chessstats.html) provided by the Chessgames database (685,801) games, the average number of moves is 40.04. Chessgames tends to only include player games of a high caliber, so this doesn't really take into account amateur tournaments. As these games are played by humans, few of them tend to end in checkmate but rather a draw by mutual agreement or a resignation in a lost position.
  
  This may not be the best source, but I've played in over 320 tournaments in my life and many of these games are imported into my personal database. The average number of moves per game is around 38.
  
  I do not have access to my Mega Database 2012 (a database provided by Chessbase) at the moment, but I will post the average number of moves of approximately 5 million historical games when I open it.
  
  > **Comments:**
  > **username_11**: Relevant? [Why does FIDE classical chess have a time limit for the first 40 moves?](https://chess.stackexchange.com/a/34890)  
  
  ---
  
  ### Answer by username_3 on 2014-03-03. Score: 44
  
  I did this graph based on 731,000 games played on the free internet chess server by players with rating above 2000 during the last 13 years with **non-blitz time controls**.
  The **average length is 79 half moves**, the **median is 70** and the **mode is 51.** There are also a lot of very short games due to people resigning early.
  
  ![Distribution of chess game length](https://i.sstatic.net/vcJAF.png)
  
  **Update:** As it turns out, the above curve can be very well approximated by a log-normal distribution. That is the logarithm of the games lengths are normally distributed. We can then consider the expected game length remaining given how many moves have already been played, which may be interesting for chess engines. It looks like this:
  
  ![enter image description here](https://i.sstatic.net/rnzQt.png)
  
  If you want to use it for figuring out how to use your time(\*), the function can be very well approximated by the following expression. (Again remember, that the result is in half moves.).
  
  `59.3 + (72830 - 2330 k)/(2644 + k (10 + k))`
  
  (\*)Though you would probably want to take other factors into consideration as well.
  
  > **Comments:**
  > **username_4**: How much better does it fit a log normal as opposed to a Weibull, Gamma, or Beta distribution?  
  > **username_5**: Do you happen to have this data on hand? I would like to have a look at it myself.  
  > **username_6**: How do rating 2 variables affect those curves?  This could be made a surface with average of game pair of ratings (assuming not large differential).  or higher dimension statistical problem is using all the ratings.  I  think lichess data from patzer to stratosphere.  I am asking because of A0 and LC0 zero-knowledge batch to good engine play trajectories, whether they sample outcomes at different phases of the games as they become better, (but also reduce their exploration intensity, by RL dilemna).  
  
  ---
  
  ### Answer by username_7 on 2018-09-14. Score: 6
  
  We can make a small analysis from a theoretical point of view:
  
  * Let us call 'n' the number of pieces on the board.
  * In a match between players of similar strength, it is expected to find ~n/2 pieces for each side.
  * When it is White's turn to move, they have 64-n/2 available squares, n/2 are occupied by rival pieces.
    That is, fc=(n/2)/ (64-n/2) is the fraction of moves that result in a piece capture
  * The same number applies for Black.
  * n=32 --> fc~1/3, at the end of the opening, with pieces fully developed
  * n=22 --> fc~1/5, middle-game
  * n=16 --> fc~1/7, end-game
  
  So, on average, we can expect that each player loses 1 piece every 5 moves approximately.
  It takes ~8\*5=40 moves to reach a population of 8 pieces vs 8 pieces.
  After 40 moves, with both "armies" reduced to its half, there is a reasonable expectation that one of them has already lost its king, and so the match is ended.
  
  
  ---
  
  ### Answer by username_8 on 2017-08-05. Score: 4
  
  The average length of chess games depends highly on the reflection time schedule since decisive errors happen very often under time pressure. Cf. <https://ingram-braun.net/public/research/parlour-games/article/statistics-length-chessbase/>
  
  
  ---
  
  ### Answer by username_9 on 2015-01-25. Score: 3
  
  Sahovski Informator publishes approximately 700 of the Best or Most Interesting games of the preceding several months, played by Grandmasters around the world. I have found the average number of moves in several volumes to converge at between 43 and 44 moves per game. This is, of course, for Grandmasters in tournaments or matches, so they are not giving up easily. Also, interestingly, the number of moves is slowly increasing as time goes forward, indicating perhaps that fewer mistakes are being made, so that games are taking longer.  
  Also, there is a small variation in length based on the openings - e4-e5; d4-d5; d4-nf6; e4-c5 etc, but it doesn't seem significant.
  
  
  ---
  
  