A standard professional baseball game is 9 innings, but there is no fixed maximum: in theory it can go on indefinitely with extra innings until one team finally finishes ahead.

Regulation innings

  • In Major League Baseball, a full game is scheduled for 9 innings.
  • Each inning has a top (visiting team bats) and a bottom (home team bats).

Extra innings and “how far can it go?”

  • If the score is tied after 9 innings, the game goes to extra innings: 10th, 11th, 12th, and so on.
  • There is no official limit on the number of innings in MLB; the game continues until one team leads at the end of a completed inning.

Longest real games

  • The longest game in Major League Baseball by innings was 26 innings, ending in a 1–1 tie because it became too dark to continue (this was in 1920, before stadium lights).
  • The longest game in professional baseball overall reached 33 innings in a 1981 minor league game between Pawtucket and Rochester.

So practically vs. theoretically

  • Theoretically, a game could last forever if both teams keep matching each other without a decisive inning.
  • In practice, extreme marathons (20+ innings) are rare, and modern rules like tiebreaker runners in extra innings are partly meant to help games end sooner.

Information gathered from public forums or data available on the internet and portrayed here.