On-base percentage plus slugging percentage (OPS), also called on-base plus slugging, is a statistic that attempts to measure a hitter's performance in baseball. It combines on-base percentage (OBP), a statistic that measures the player's ability to get safely on base, with slugging percentage (SLG), which measures the player's ability to get hits, especially extra-base hits. Many people look at OPS as a valuable tool for assessing the offensive skill of a player, but some critics say that it undervalues on-base percentage and over-values extra-base hits, so it misrepresents a hitter's value to his team.

#### Formulas

A player's on-base percentage is the sum of his or her hits (H); walks, or bases on balls (BB); and times hit by a pitch (HBP) divided by the sum of his or her official at-bats (AB), walks, sacrifice flies (SF) and times hit by a pitch. The formula looks like this:

**OBP = (H + BB + HBP) / (AB + BB + SF + HBP)**
The other part of OPS is slugging percentage, which measures the total bases (TB) a player achieves on hits. A single (1B) is one base, a double (2B) is two bases, a triple (3B) is three bases, and a home run (HR) is four bases. The formula for slugging percentage is simple:

**SLG = TB / AB**
The formula also can be written this way:

**SLG = (1B + (2 x 2B) + (3 x 3B) + (4 x HR)) / AB**
On-base plus slugging is simply the player's on-base percentage plus his or her slugging percentage. The formula can be written simply as **OPS = OBP + SLG**, or a longer version can be written with all of the components included:

**OPS = AB(H + BB + HBP) + TB(AB + BB + SF + HBP) / AB(AB + BB + SF + HBP)**
#### Useful Statistic

Many people consider OPS to be useful for measuring a batter's skills. Getting on base without an out being recorded correlates well with helping a team score runs. This is true no matter how the player gets on base, which is why on-base percentage is often considered a better measure of a batter's contributions to the team than simple batting average, which is calculated by dividing the number of hits by the number of at-bats. Batting average, for example, doesn't give the batter credit for drawing a walk.

OPS also rewards a batter's ability to get hits, especially extra-base hits, by including slugging percentage as a component. A double typically is more valuable to a team than a single, and this is reflected in the formula. Home runs are the most valuable type of hit, and the formula gives them the most weight.

#### Typical Numbers

In Major League Baseball, the average OPS in the early 21st century was about .750. The average in the American League (AL), which uses a designated hitter (DH) except during interleague games played at National League (NL) ballparks, was about .757 — 12 points higher than in the NL, which does not use a DH except in interleague games at AL ballparks.

An OPS of 1.000 is considered excellent for a major league player. Only a few players who have batted more than 500 times achieve this mark in most seasons. As of 2012, just seven players in major league history had retired with a career OPS of 1.000 or better. The record is held by slugger Babe Ruth, who had a career OPS of 1.164 from 1914 to 1935.

At lower levels of baseball, such as in high school or youth leagues, highly skilled players often are able to achieve much higher averages in various batting statistics, including OPS. This is because there is a wider range in the skill levels of batters and pitchers at this level than there is in the major leagues. For example, a great high school hitter might often face lesser-skilled pitchers, whereas a major league hitter usually will face very talented pitchers. Therefore, at lower levels of baseball, players can be measured more accurately measured by comparing their statistics to those of their peers than to those of major league players.

#### Criticisms of OPS

Although many people consider OPS to be a useful tool, critics point out several flaws in this statistic. These typically relate to precisely how valuable the various outcomes for a hitter are to the team and how well certain statistics correlate to a team's success. For example, on-base percentage is more highly linked to team success than slugging percentage, but the OPS formula gives the two statistics equal weight.

Another criticism of OPS is based on the formula for slugging percentage. According to the formula, a double is worth twice as much as a single, a triple is worth three times as much, and so on. In terms of value to the team, however, the difference between the types of hits has been found to be much less. Depending on the method used to calculate the value of each type of hit to the team, a double has been found to be worth only about 40% to 60% more than a single, with a triple being worth about 70% to 130% more and a home run worth about 120% to 200% more — or no more than three times the value of a single. As such, slugging percentage — and therefore OPS — is considered by critics to overvalue extra-base hits.