In baseball, WAR stands for "Wins Above Replacement". It is a non-standardized sabermetric baseball statistic that measures a players total contributions to his team. WAR attempts to measure a players value in all facets of the game by deciphering how many more wins hes worth than a replacement-level player at his same position. A replacement-level player is defined as a Minor League replacement or a readily available fill-in free agent.

The formula for calculating WAR differs slightly depending on the source, but all use similar basic principles. For position players, WAR is calculated as the number of runs above average a player is worth in his batting, baserunning, and fielding, plus an adjustment for position, an adjustment for league, and the number of runs provided by a replacement-level player, divided by runs per win. For pitchers, different WAR computations use either runs allowed per nine innings pitched or fielding independent pitching. Those numbers are adjusted for league and ballpark. Then, using league averages, the resulting numbers and his innings pitched total.

WAR is recognized as an official stat by Major League Baseball and by the Elias Sports Bureau, and ESPN publishes the Baseball-Reference version of WAR on its own statistics pages for position players and pitchers. WAR has become a widely accepted statistic in the media and is often a point of consideration for annual awards such as the Cy Young and MVP. It can provide a quick snapshot of the value of a player and allow for comparisons across positions and even years.