How Major League Baseball players can turn to a robot to challenge balls, strikes this year

Robot umpires are coming to the big leagues this year.

The Automated Ball-Strike (ABS) Challenge System will be introduced in the form of a challenge system in which the home plate umpire makes each call, with teams able to appeal to a computer system.

Robot umpires have been tested in the minor leagues since 2019, with recent trials at Triple-A since 2022, during MLB spring training last year and at the 2025 All-Star Game in Atlanta.

Here's what to know about MLB's robot umpires.

Stadiums are outfitted with cameras that track each pitch and determine whether it crossed home plate within the strike zone. In early testing, umpires wore earpieces and heard "ball" or "strike," then relayed the call to players and fans with traditional hand signals.

The challenge system adds a wrinkle. Human umpires call every pitch, but each team can challenge two calls per game. Teams that lose both challenges get one additional challenge in each extra inning. A team keeps its challenge if the appeal is successful, similar to video review rules in the major leagues, which were first used for home run calls in August 2008 and expanded to a wider range of plays for the 2014 season.

Only the batter, pitcher or catcher may challenge a call, signalling with the tap of a helmet or cap. Help from the dugout is not allowed. A challenge must be made within two seconds, and a graphic of the pitch and strike zone is shown on the scoreboard and broadcast feed. The umpire then announces the updated count.

Challenges during spring training last year averaged 13.8 seconds.

A Hawk-Eye pose-tracking system of cameras tracks pitches and determines whether they fall within a strike zone based on the each batter's height, measured without shoes. Each