OBP

On-base percentage (OBP) is a baseball statistic that measures how frequently a batter reaches base via hit, walk, or being hit by a pitch. It provides a view of a hitter’s overall ability to avoid making outs, beyond just hitting for average.

OBP is calculated as: OBP = (H + BB + HBP) / (AB + BB + HBP + SF), where H is hits, BB is bases on balls (including intentional walks), HBP is hit by pitch, AB is at-bats, and SF is sacrifice flies. Reaching base through fielder’s choice or as a result of a dropped third strike is treated differently depending on the rule set, but generally those outcomes do not count as hits or walks in the numerator.

In usage, OBP is valued because it accounts for walks and hit-by-pitch as productive plate appearances, unlike batting average which only considers hits. It is often paired with slugging percentage to form OPS (on-base plus slugging) as a quick measure of overall offensive ability. Contemporary leagues typically see OBP values around the .320 to .360 range for many players, with elite hitters exceeding .400 in a given season. OBP is influenced by a player’s plate discipline, contact ability, and the ballpark or era in which they play.

Historically, OBP gained prominence in sabermetrics during the late 20th century and is now a standard component of player evaluation alongside other metrics such as SLG, OPS, and more advanced models like wOBA. While it provides a reliable picture of how often a player reaches base, OBP does not measure power or baserunning quality, and should be interpreted in conjunction with other statistics.