Answers.Body: <p>Yes, 100% is possible. But having it happen doesn't mean much.</p>
  <pre><code>[FEN &quot;&quot;]
  
  1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 d6 8. c3 O-O 9. h3
  </code></pre>
  <p>If you run this game through the analysis it will show 100% accuracy for both sides. All the moves are &quot;book moves&quot; which the analysis will give full credit for.</p>
  <p>Now take the following game:</p>
  <pre><code>[FEN &quot;&quot;]
  1. b4 1... g5 2. Bb2 f6 3. e4 h5 4. Be2 b6 5. Bxh5+ Rxh5 6. Qxh5#
  </code></pre>
  <p>It gives White an accuracy of 99.7, despite five &quot;Best Moves&quot; and one &quot;Book&quot;. If I go to the Details tab, it gives White an accuracy of 99.68 on moves involving the queen (and also on moves involving the bishop or pawn.) But the only queen move was <em>checkmate</em>! So, for some reason, it's refusing to give 100% even on moves which are obviously best.</p>
  <p>Don't make the mistake of taking those accuracy scores too seriously. The analysis runs only to a moderate depth and the results would change if it ran deeper (in your scenario with high-level engines playing against each other, the analysis would possibly mark some of the moves as not best just because it didn't see far enough to know why those engines played them.) And, clearly, there is something else going on which causes the analysis to not score moves as 100% even if those moves are perfect.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-23T20:17:33.590Z
Answers.Text: You could even play 1.e4, resign, and get 100% accuracy, right?
Answers.UserDisplayName: David
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-24T01:52:11.190Z
Answers.Text: Not all book moves get 100% accuracy. See https://chess.stackexchange.com/questions/31591/why-is-whites-accuracy-99-7-instead-of-100-0
Answers.UserDisplayName: Zuriel
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-24T09:10:24.500Z
Answers.Text: @Zuriel Take the last move of the game in that link - the one NOT in book - out of the game, and run the report. 100%.
Answers.UserDisplayName: D M
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-05-23T11:46:35.413Z
Answers.LastActivityDate: 2021-05-23T11:46:35.413Z
Answers.UserDisplayName: D M
Body: <p><a href="https://i.sstatic.net/X4Rd2.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/X4Rd2.png" alt="Accuracy example" /></a></p>
  <p>On chess.com, I have analyzed several games by humans and even by machines. The highest accuracy I've ever seen is 99.7. I'm no expert at what contributes to a good or bad score, but I know the obvious; good moves equals higher accuracy store.</p>
  <p>I have simulated a game with the highest-level CPU against itself. Even after analyzing it, the scores were only 99.7. Is 100 even possible? How do you determine the accuracy of 100?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-23T10:01:19.557Z
Comments.Text: When W offers a draw on move 1 and B accepts, that is 100 per cent accuracy.
Comments.UserDisplayName: Aravind
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-23T10:20:01.547Z
Comments.Text: please specify you're talking about accuracy on chess.com because there is no universal definition.
Comments.UserDisplayName: sleepy
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-05-23T20:18:19.483Z
Comments.Text: @sleepy unfortunately more and more people everyday think chess and chess.com are synonnimous
Comments.UserDisplayName: David
Tags: <chess.com>
Title: Is an accuracy of 100 possible?
ThreadText: # Is an accuracy of 100 possible?
  
  (Asked by: username_0 on 2021-05-23)
  
  [![Accuracy example](https://i.sstatic.net/X4Rd2.png)](https://i.sstatic.net/X4Rd2.png)
  
  On chess.com, I have analyzed several games by humans and even by machines. The highest accuracy I've ever seen is 99.7. I'm no expert at what contributes to a good or bad score, but I know the obvious; good moves equals higher accuracy store.
  
  I have simulated a game with the highest-level CPU against itself. Even after analyzing it, the scores were only 99.7. Is 100 even possible? How do you determine the accuracy of 100?
  
  **Tags:** chess.com
  
  > **Comments:**
  > **username_1**: When W offers a draw on move 1 and B accepts, that is 100 per cent accuracy.  
  > **username_2**: please specify you're talking about accuracy on chess.com because there is no universal definition.  
  > **username_3**: @username_2 unfortunately more and more people everyday think chess and chess.com are synonnimous  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_4 on 2021-05-23. Score: 6 | Accepted answer
  
  Yes, 100% is possible. But having it happen doesn't mean much.
  [FEN ""]
  
  1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 d6 8. c3 O-O 9. h3
  
  If you run this game through the analysis it will show 100% accuracy for both sides. All the moves are "book moves" which the analysis will give full credit for.
  Now take the following game:
  [FEN ""]
  1. b4 1... g5 2. Bb2 f6 3. e4 h5 4. Be2 b6 5. Bxh5+ Rxh5 6. Qxh5#
  
  It gives White an accuracy of 99.7, despite five "Best Moves" and one "Book". If I go to the Details tab, it gives White an accuracy of 99.68 on moves involving the queen (and also on moves involving the bishop or pawn.) But the only queen move was checkmate! So, for some reason, it's refusing to give 100% even on moves which are obviously best.
  Don't make the mistake of taking those accuracy scores too seriously. The analysis runs only to a moderate depth and the results would change if it ran deeper (in your scenario with high-level engines playing against each other, the analysis would possibly mark some of the moves as not best just because it didn't see far enough to know why those engines played them.) And, clearly, there is something else going on which causes the analysis to not score moves as 100% even if those moves are perfect.
  
  > **Comments:**
  > **username_3**: You could even play 1.e4, resign, and get 100% accuracy, right?  
  > **username_5**: Not all book moves get 100% accuracy. See https://chess.stackexchange.com/questions/31591/why-is-whites-accuracy-99-7-instead-of-100-0  
  > **username_4**: @username_5 Take the last move of the game in that link - the one NOT in book - out of the game, and run the report. 100%.  
  
  ---
  
  