Answers.Body: <h2>Stats from Mega Database 2023</h2>
  <p>Of the 10,034,661 total games in the version of Mega Database 2023 I use, 7,084,704 are between players with more than 1600 Elo. Of these:</p>
  <ul>
  <li><p>3,388,825 begin with e4.</p>
  <ul>
  <li>0-0 was played by White in 2,511,122 of these (<strong>74.1%</strong>).</li>
  <li>0-0-0 was played by White in 560,528 of these (<strong>16.5%</strong>).</li>
  </ul>
  </li>
  <li><p>2,365,980 begin with d4.</p>
  <ul>
  <li>0-0 was played by White in 1,880,115 of these (<strong>79.5%</strong>).</li>
  <li>0-0-0 was played by White in 203,806 of these (<strong>8.6%</strong>).</li>
  </ul>
  </li>
  </ul>
  <p>For reference, 0-0 was played by White in 5,514,441 games (<strong>77.8%</strong> of the time), and 0-0-0 in 821,270 games (<strong>11.6%</strong> of the time).</p>
  <hr />
  <p>I used <a href="https://cql64.com" rel="noreferrer">CQLi</a> to search the Mega Database, specifically the <code>find move from K o-o</code> and <code>find move from K o-o-o</code> filters.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-12-23T13:24:31.870Z
Answers.LastActivityDate: 2024-12-23T13:24:31.870Z
Answers.UserDisplayName: double-beep
Body: <p>White plays O-O 80% of the time and O-O-O 9.6% of the time. I'm looking for the same statistics but after 1.e4 and after 1.d4. I'm pretty sure that O-O-O is rarer after 1.d4 than after 1.e4. But how much rarer? I want to see the numbers.</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-12-15T10:43:41.060Z
Comments.Text: Are you interested in stats from online chess games, official games (i.e. games in the Mega Database) or both?
Comments.UserDisplayName: double-beep
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-12-15T11:00:17.643Z
Comments.Text: @double-beep: Any of the two would do, as I don't care too much about accuracy. But I would prefer games by players below 1600 Elo to be excluded.
Comments.UserDisplayName: Fate
Tags: <opening><statistics><castling><1.e4><1.d4>
Title: What is the probability that White will play O-O or O-O-O after 1.e4 and 1.d4?
ThreadText: # What is the probability that White will play O-O or O-O-O after 1.e4 and 1.d4?
  
  (Asked by: username_0 on 2024-12-15)
  
  White plays O-O 80% of the time and O-O-O 9.6% of the time. I'm looking for the same statistics but after 1.e4 and after 1.d4. I'm pretty sure that O-O-O is rarer after 1.d4 than after 1.e4. But how much rarer? I want to see the numbers.
  
  **Tags:** opening, statistics, castling, 1.e4, 1.d4
  
  > **Comments:**
  > **username_1**: Are you interested in stats from online chess games, official games (i.e. games in the Mega Database) or both?  
  > **username_0**: @username_1: Any of the two would do, as I don't care too much about accuracy. But I would prefer games by players below 1600 Elo to be excluded.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2024-12-23. Score: 6 | Accepted answer
  
  ## Stats from Mega Database 2023
  
  Of the 10,034,661 total games in the version of Mega Database 2023 I use, 7,084,704 are between players with more than 1600 Elo. Of these:
  
  * 3,388,825 begin with e4.
  
    + 0-0 was played by White in 2,511,122 of these (**74.1%**).
    + 0-0-0 was played by White in 560,528 of these (**16.5%**).
  * 2,365,980 begin with d4.
  
    + 0-0 was played by White in 1,880,115 of these (**79.5%**).
    + 0-0-0 was played by White in 203,806 of these (**8.6%**).
  
  For reference, 0-0 was played by White in 5,514,441 games (**77.8%** of the time), and 0-0-0 in 821,270 games (**11.6%** of the time).
  
  ---
  
  I used [CQLi](https://cql64.com) to search the Mega Database, specifically the `find move from K o-o` and `find move from K o-o-o` filters.
  
  
  ---
  
  