Baseball Statistics - Win-Loss Percentage (Winning Percentage or WP%)

The objective of a baseball team is to win games. In order to win games, a team must outscore it's opponent more often than not. In this article, we'll examine how to calculate a team's Win-Loss Percentage (also called "Winning Percentage" or WL%).

A team's Win-Loss Percentage is quite simply the percentage of their total games in which they won. To calculate a team's winning percentage, take the team's total wins and total losses, and fill them into the formula below:

WL% = Wins / (Wins + Losses)

Win-Loss Percentage is written as a decimal with three spaces after the decimal point. For example, a major league team plays their regular 162 game schedule, winning 81 games and losing 81. You calculate their WL% by dividing 81 Wins by 162 (81 wins and 81 losses). The team in question would have a .500 Winning Percentage.

A .500 wining percentage is a team's "break even" point, below that, and they certainly aren't a very good team. In order to contend for a division championship, a team usually needs a Winning Percentage of about .580 or higher.

Of course, a .510 WP% might win the division, and a .650 WP% might not, as it all depends on what the other teams are doing. For example, in 2005 the Philadelphia Phillies won 88 games and lost 74, a .543 WP%. The Atlanta Braves, who are in the same division as the Phillies (the National League East) won 90 games and lost 72, a .556, edging the Phillies for the division title by two games. Meanwhile, in the National League West, the San Diego Padres won the division with an 82-80 record, a .506 WP%.

Since Major League Baseball switched to the 162 game schedule in 1961 (previously, a season had been 154 games), the highest single season Win-Loss Percentage belongs to the 2001 Seattle Mariners. That season, the Mariners won 116 games and lost only 46, for an amazing .716 Winning Percentage. That season, the Mariners finished 14 games ahead of the Oakland A's in the division, despite the A's winning 102 games and posting a .630 Winning Percentage. The Mariners would beat the Cleveland Indians in the Division series, 3 games to 2, but eventually lose to the New York Yankees in the American League Championship Series, 4 games to 1.

The lowest Winning Percentage from the same time period belongs to the 1962 New York Mets. The Mets, in their first year of existence after the major leagues expanded, won only 40 games, and lost 120. That works out to a horrific .250 Win-Loss Percentage. The Mets finished 60.5 games behind the National League champions that year, the San Francisco Giants, who finished with 102 wins for a .624 WP%. Back on those days, there were no divisions, each league had 10 teams, and the one with the most wins represented the league in the World Series.