Baseball Stats FAQ

Baseball stats measure what happened on the field, letting fans, players, coaches, and analysts compare performance across players, teams, and eras using a shared numeric language.

A box score is the summary chart of a completed game, showing each player's key stats (at-bats, hits, runs, and RBIs for hitters; innings, runs, and strikeouts for pitchers), plus the final score and other game notes.

A slash line is the shorthand way of writing a hitter's batting average, on-base percentage, and slugging percentage together, separated by slashes, for example .300/.380/.500.

Traditional stats (batting average, RBIs, wins, ERA) come straight from raw counting numbers and have been tracked since the 1800s. Advanced stats (OPS+, WAR, FIP, and others) use formulas designed to better isolate a player's individual contribution, often adjusting for park effects, league conditions, or role.

Sabermetrics takes its name from SABR, the Society for American Baseball Research, and refers to the statistical analysis of baseball built around advanced, context-adjusted stats rather than only traditional counting numbers.

A counting stat adds up over a season or career, like hits, home runs, or wins, and naturally grows the more a player plays. A rate stat expresses performance as a ratio, like batting average or ERA, so it can be compared fairly regardless of how many games someone has played.

The core formulas are the same, but the numbers that count as good or average shift by level, since high school, college, minor league, and MLB pitching and defense are not equally strong, which is why a .400 batting average might be common in high school but historic in MLB.

Offensive stats measure a player's hitting and baserunning contributions (batting average, OBP, SLG, stolen bases), while defensive stats measure fielding contributions (fielding percentage and more advanced defensive metrics).

Major League Baseball's official statistics are compiled and verified by MLB's own statistics group, with Baseball-Reference, FanGraphs, and MLB.com among the most widely used public sources for looking up and researching those numbers.

In May 2024, MLB officially integrated Negro Leagues statistics from 1920 to 1948 into its all-time record book, which moved several Negro Leagues stars, most notably Josh Gibson, into the top spots on multiple career and single-season leaderboards.

Batting average measures how often a hitter gets a hit per official at-bat, calculated as hits divided by at-bats, and is written as a three-decimal number like .300.

Divide a player's total hits by their total at-bats (batting average = H / AB). A player with 150 hits in 500 at-bats has a .300 batting average.

A plate appearance counts every trip to the plate, while an at-bat excludes walks, hit-by-pitches, sacrifices, and catcher's interference, since those outcomes are not counted as an official at-bat for batting average purposes.

No, walks are not counted as at-bats, so they do not affect batting average at all, positively or negatively, though they do count toward on-base percentage.

No, being hit by a pitch is not treated as an at-bat, so it has no effect on batting average, though like a walk it does count toward on-base percentage.

No, a sacrifice fly is excluded from at-bats entirely, so it neither helps nor hurts batting average, even though it produces a run and counts against a player's plate appearances.

No, a sacrifice bunt is also excluded from at-bats, so like a sacrifice fly it has no effect on batting average.

Yes, a .300 batting average is widely considered a strong benchmark in MLB, generally putting a hitter among the better hitters in the league for that season.

A .250 batting average is roughly average to slightly below average for an MLB regular, a common line for a solid everyday player who contributes in other ways.

Yes, a .333 batting average is excellent, translating to a hit in exactly one of every three at-bats and typically ranking among the better marks in MLB in a given season.

Ted Williams hit .406 for the Boston Red Sox in 1941, and remains the last player to hit .400 or better over a full MLB season.

Because high school pitching and defense are far less polished than professional baseball, a batting average of .400 or higher is often considered a strong mark at the high school level, compared to a .300 benchmark in MLB.

Following MLB's 2024 integration of Negro Leagues statistics, Josh Gibson is now recognized as the official career batting average leader at .372, surpassing Ty Cobb's previously recognized mark of .367.

Josh Gibson's .466 average for the 1943 Homestead Grays is now MLB's officially recognized single-season record, ahead of Rogers Hornsby's .424 in 1924, which had long been considered the mark to beat in American League and National League play.

OBP stands for on-base percentage, a stat measuring how often a hitter reaches base safely by any means, not just hits.

OBP is calculated as (hits + walks + hit-by-pitches) divided by (at-bats + walks + hit-by-pitches + sacrifice flies), capturing every common way a hitter reaches base safely.

Batting average only counts hits per at-bat, while on-base percentage also credits walks and hit-by-pitches, giving a fuller picture of how often a hitter avoids making an out.

An OBP of .360 or higher is generally considered good in MLB, while an OBP approaching or exceeding .400 is considered excellent, at the level of the league's best hitters.

SLG stands for slugging percentage, a stat measuring the total number of bases a hitter records per at-bat, which rewards extra-base hits more heavily than singles.

Slugging percentage is total bases divided by at-bats, where a single counts as one base, a double as two, a triple as three, and a home run as four.

A slugging percentage of .450 or higher is generally considered good in MLB, with .500 or better considered a genuine power threat and .550 or above among the game's elite sluggers.

Total bases is the sum of all bases a hitter earns through hits in a game or season, so a player with one single, one double, and one home run in a game would have seven total bases.

An extra-base hit is any hit that is not a single, meaning doubles, triples, and home runs, all of which boost a hitter's slugging percentage more than a single would.

No, slugging percentage weighs hits by how many bases they're worth, while batting average treats every hit, single or home run, exactly the same.

OPS stands for on-base plus slugging, a single number created by adding a hitter's on-base percentage and slugging percentage together to summarize both their ability to reach base and their power in one stat.

OPS stands for on-base plus slugging.

OPS is calculated simply by adding on-base percentage and slugging percentage together (OPS = OBP + SLG).

An OPS around .800 is generally considered good in MLB, .900 or higher is considered great, and 1.000 or above is an elite, MVP-caliber level reserved for a small handful of hitters in a given season.

Across MLB history, league-average OPS has typically sat somewhere in the neighborhood of .700 to .750, though the exact league-wide figure shifts somewhat from season to season.

Following the 2024 integration of Negro Leagues statistics, Josh Gibson is now recognized as MLB's career OPS leader at 1.177, ahead of Babe Ruth's previously top-ranked 1.164 mark.

OPS+ takes a hitter's OPS and adjusts it for their home ballpark and league scoring environment, then scales it so that 100 always represents a league-average hitter for that season.

Because OPS+ is scaled around 100 as league average, a mark of 125 means a hitter was 25 percent better than league average, while 80 means 20 percent worse, making it easy to compare hitters across different ballparks and eras.

Raw OPS does not account for the fact that some ballparks and eras favor hitters far more than others, so OPS+ adjusts for those differences, allowing fairer comparisons between, for example, a hitter in a pitcher-friendly park and one in a hitter-friendly park.

No, OPS+ is a hitting stat. Pitchers have their own park-and-league-adjusted equivalent called ERA+.

ERA stands for earned run average, a pitching stat measuring how many earned runs a pitcher allows, on average, per nine innings pitched.

ERA is calculated by dividing a pitcher's earned runs allowed by their total innings pitched, then multiplying by nine, giving a rate of earned runs allowed per nine-inning game.

An earned run is a run that scores without help from a defensive error or passed ball, while an unearned run is charged when a fielding mistake contributed to the run scoring, and unearned runs do not count against a pitcher's ERA.

An ERA under 3.00 is generally considered excellent in MLB, an ERA around 3.50 to 4.00 is considered roughly average to solid, and an ERA above 4.50 is considered below average for a starting pitcher.

Because relievers typically pitch shorter, higher-leverage outings, elite relievers and closers often post ERAs comfortably under 3.00, with the very best sometimes posting ERAs near or under 2.00 over a full season.

Nine innings is the standard length of a regulation baseball game, so ERA is scaled to that length to let fans compare a starter who throws 200 innings with a reliever who throws 60 on an equal, per-game basis.

Only partially. ERA excludes runs tied directly to a scored error, but it still holds a pitcher responsible for balls put in play that a below-average defense fails to convert into outs, which is part of why FIP was created as an alternative.

Because pitching and defense are less refined at the amateur level, ERA benchmarks are generally lower than pro ball, and an ERA in the 2.00 to 3.00 range is often viewed as a strong mark in high school and college baseball.

A sub-2.00 ERA means a pitcher is allowing fewer than two earned runs per nine innings on average, a rare, standout level of performance typically achieved by only a handful of starting pitchers across MLB in a given season.

RA9 measures all runs allowed per nine innings, earned or unearned, unlike ERA which only counts earned runs, and it is sometimes used in advanced pitching models as an alternative baseline.

WHIP stands for walks plus hits per inning pitched, a stat that measures how many baserunners a pitcher allows via walks and hits, on average, in each inning.

WHIP is calculated by adding a pitcher's total walks and hits allowed, then dividing that sum by their total innings pitched (WHIP = (BB + H) / IP).

A WHIP under 1.00 is considered elite in MLB, a WHIP around 1.20 to 1.30 is considered solid and roughly average, and a WHIP above 1.40 is generally considered below average.

FIP stands for fielding independent pitching, an ERA-style stat that only considers outcomes a pitcher directly controls, home runs, walks, hit-by-pitches, and strikeouts, while removing the influence of the defense playing behind him.

ERA is affected by how well a pitcher's defense turns batted balls into outs, while FIP scales a pitcher's home runs, walks, and strikeouts to an ERA-like number and deliberately ignores balls put in play, so it is often used to judge a pitcher's performance independent of their fielders.

FIP is calculated from a weighted combination of home runs, walks, hit-by-pitches, and strikeouts per inning pitched, plus a constant that is recalculated every season so that league-average FIP lines up with league-average ERA.

The constant exists purely to put FIP on the same numeric scale as ERA for that season, so a FIP of 3.50 can be compared directly and intuitively against a pitcher's or league's ERA.

ERA+ adjusts a pitcher's ERA for their home ballpark and league scoring environment, then scales the result so that 100 represents a league-average pitcher, similar in spirit to OPS+ for hitters.

A higher ERA+ is better. Unlike raw ERA, where a lower number is better, ERA+ is scaled so that above 100 means better than league average and below 100 means worse, mirroring how OPS+ works for hitters.

K/9 measures a pitcher's strikeouts per nine innings pitched, a rate stat used to gauge how effectively a pitcher misses bats regardless of how many innings they've thrown.

BB/9 measures a pitcher's walks allowed per nine innings pitched, a rate stat used to gauge a pitcher's control and command.

A quality start is credited to a starting pitcher who throws at least six innings while allowing three earned runs or fewer, a common shorthand benchmark for a solid, if not spectacular, start.

WAR stands for wins above replacement, a single all-in-one stat that estimates how many more wins a player is worth to their team compared to a hypothetical readily available replacement-level player at the same position.

WAR combines a player's batting, baserunning, and fielding value, or for pitchers their run prevention, into a single runs-based estimate, then converts that runs figure into an estimated number of wins using the approximate relationship between runs and wins in baseball.

Baseball-Reference's version (often called bWAR or rWAR) and FanGraphs' version (fWAR) use different underlying methods, most notably for pitchers, where bWAR leans on actual runs allowed and fWAR leans on FIP, which can produce meaningfully different results for the same season.

A single-season WAR of 5 or higher is generally considered an All-Star-caliber season, while a WAR of 8 or above is considered an MVP-caliber season reserved for a handful of the league's best players.

A WAR near zero means a player performed at roughly a replacement level, meaning a team likely would have gotten similar production from a readily available minor league call-up or bench player in that role.

Yes, a negative WAR means a player's overall performance was estimated to be worse than what a replacement-level player would have provided, which can happen even to established players during a poor season.

Babe Ruth holds the highest career WAR in MLB history, with an estimated total near 182.6 wins above replacement across his hitting and pitching value combined.

Babe Ruth's 1923 season, with a WAR near 14.1, is generally cited as the highest single-season WAR total in MLB history.

Analysts and front offices have long used a rough dollar-per-WAR estimate to help value free agents, though the exact figure drifts higher over time as player salaries rise, so it is better understood as a moving benchmark than a fixed number.

The underlying idea is the same, wins contributed above a replacement-level player, but the inputs differ: hitters' WAR centers on batting, baserunning, and fielding, while pitchers' WAR centers on run prevention over the innings they throw.

AB stands for at-bats, the number of times a player has batted in a way that counts toward batting average, excluding walks, hit-by-pitches, sacrifices, and catcher's interference.

PA stands for plate appearances, every completed trip to the plate for a hitter, including at-bats, walks, hit-by-pitches, and sacrifices.

H stands for hits, the number of times a batter safely reached base on a batted ball without the help of an error or a fielder's choice.

R stands for runs scored, crediting a player every time they cross home plate to score.

RBI stands for runs batted in, credited to a batter whenever their action at the plate directly drives in a run, whether by a hit, a walk with the bases loaded, a sacrifice fly, or another qualifying play.

HR stands for home runs, hits on which the batter circles all the bases and scores, most commonly by hitting the ball out of play in fair territory.

BB stands for base on balls, more commonly called a walk, awarded to a batter who receives four pitches out of the strike zone during one plate appearance.

SO and K both stand for strikeout, recorded when a batter accumulates three strikes in a single plate appearance.

SB stands for stolen base, credited to a baserunner who advances to the next base during a play, typically a pitch, without the help of a hit, walk, or error.

CS stands for caught stealing, recorded against a baserunner who attempts to steal a base but is thrown out before reaching it safely.

HBP stands for hit by pitch, awarded to a batter struck by a pitched ball, entitling them to first base.

SF stands for sacrifice fly, a fly ball out that allows a runner to score from third base after the catch.

IP stands for innings pitched, tracked in thirds, so a pitcher who records one out in an inning is credited with one-third of an inning pitched.

GIDP stands for grounded into double play, tracking how often a batter hits into a double play, which ends two outs on a single batted ball.

Yes, a batting average around .200, sometimes called the "Mendoza Line," is widely viewed as a marker of a struggling hitter in MLB, though a player can still hold a roster spot on the strength of elite defense or other skills.

The Mendoza Line is a nickname for a batting average around .200, referencing infielder Mario Mendoza, used informally as the threshold below which a hitter's offense is considered a serious liability.

"Batting 500" or "batting a thousand" are casual expressions borrowed from a .500 or 1.000 batting average, meaning succeeding at nearly everything attempted, and are sometimes used loosely outside baseball as well.

Babe Ruth holds the highest career OPS+ in MLB history, a mark that reflects just how far above his league-average contemporaries he performed across his career.

Barry Bonds hit 73 home runs for the San Francisco Giants in 2001, the current MLB single-season home run record.

Barry Bonds holds the MLB career home run record with 762, ahead of Hank Aaron's long-standing mark of 755.

Mariano Rivera holds the MLB career saves record with 652, built over 19 seasons with the New York Yankees.

A stolen base success rate of roughly 75 percent or higher is generally considered good in MLB, since the break-even point where a caught stealing costs about as much value as a stolen base gains is estimated to be somewhere in that range.

Yes, a full-season WHIP at or under 1.00 is achieved by only a small handful of MLB pitchers in a given year, and is generally viewed as an elite, top-of-the-league mark.

A five-tool player is a scouting term, not a single stat, describing a player who rates well in all five core skills: hitting for average, hitting for power, baserunning speed, throwing arm strength, and fielding ability.

Extremely rare. No MLB player has hit .400 or better over a full season since Ted Williams's .406 in 1941, making it one of the sport's most enduring statistical milestones.

Yes, MLB has gone through recognizable high-offense and low-offense eras, so what counts as a strong ERA or OPS in one period can look different in another, which is exactly why park- and league-adjusted stats like ERA+ and OPS+ exist.

Baseball-Reference, FanGraphs, and MLB.com's official stats site are among the most widely used sources for current MLB stat leaderboards, player pages, and historical statistics.

Both track essentially the same games, but they differ in how they calculate certain advanced stats, most notably WAR, and each site has its own layout, historical depth, and additional stat tools.

Small differences usually come down to which advanced-stat formula a site uses (for example, bWAR versus fWAR) or how recently the page was updated, rather than any disagreement about the underlying box score events.

The core formulas like batting average, OBP, and ERA carry over from baseball to softball largely unchanged, though rules nuances like different distances and pitching styles mean league-wide benchmarks can differ somewhat between the two sports.

No, official MLB regular-season stats and postseason stats are tracked and reported separately, so a player's career stat totals typically refer to regular-season play unless a postseason total is explicitly noted.

Advanced, context-adjusted stats like WAR, OPS+, and FIP help separate a player's individual contribution from the effects of their ballpark, teammates, and era, which is especially useful for comparing players across different seasons or generations.

Yes, the core formulas behind batting average, OBP, SLG, OPS, ERA, and WHIP are all simple enough to calculate by hand or in a basic spreadsheet using nothing more than a player's raw counting stats.

Batting average and ERA are usually the easiest entry points, since both are simple ratios, hits per at-bat and earned runs per nine innings, before moving on to combination stats like OPS and adjusted stats like OPS+ and WAR.