Baseball stats are written as short codes like AB, BB, HBP, RBI, ERA and OPS. This glossary explains 62 of the most common ones in plain words, with the formula and a link to learn more. Use the search box to find any code fast.
A baseball box score looks like a secret code at first. Each column is a short abbreviation for one stat, and the same letters can mean different things for a hitter and a pitcher. For example, BB is a walk drawn for a hitter and a walk allowed for a pitcher. This guide breaks the codes into four groups: hitting, pitching, fielding and team stats.
Quick map
- Hitting stats: AB, H, HR, RBI, BB, HBP, AVG, OBP, SLG, OPS, BABIP.
- Pitching stats: IP, ER, ERA, WHIP, FIP, K/9, QS.
- Fielding stats: E, PO, A, DP, FPCT.
- Team stats: W-L, GB, magic number.
How to Read a Box Score Line
Here is a typical batting line, and what each part means:
- 4 AB: four official at-bats.
- 2 H: two hits, one a double and one a home run.
- 2 R: he scored twice.
- 3 RBI: he drove in three runs.
- 1 BB: one walk, which is not an at-bat.
- 1 SO: he struck out once.
He had 5 plate appearances (4 AB + 1 BB), and a .500 batting average for the game (2 ÷ 4). And for a pitcher, a line looks like this: 6.0 IP, 5 H, 2 ER, 1 BB, 7 K. He pitched six innings, gave up five hits and two earned runs, walked one and struck out seven. His ERA for that start was 3.00 (9 × 2 ÷ 6), and you can work out any line with our ERA calculator.
Hitting Stats
| Abbr. | Stat and meaning | Formula | Learn more |
|---|---|---|---|
| PA | Plate appearances Every completed trip to the plate, including walks, hit by pitch and sacrifices. | AB + BB + HBP + SF + SH | |
| AB | At-bats Trips to the plate that count toward batting average. Walks, hit by pitch and sacrifices are not at-bats. | PA − BB − HBP − SF − SH | |
| H | Hits Times the batter reached base safely on a fair ball with no error or fielder's choice. | 1B + 2B + 3B + HR | What counts as a hit |
| 1B | Singles Hits that get the batter to first base. | H − 2B − 3B − HR | |
| 2B | Doubles Hits that get the batter to second base. | — | |
| 3B | Triples Hits that get the batter to third base. | — | |
| HR | Home runs Hits that let the batter score on the play, usually over the fence. | — | |
| R | Runs Times a player crossed home plate. | — | |
| RBI | Runs batted in Runs that score because of the batter's action, such as a hit, walk with the bases loaded or sacrifice fly. | — | |
| BB | Base on balls (walks) Four balls in one plate appearance. The batter goes to first base for free. | — | What is a BB |
| IBB | Intentional walks Walks the defense chooses to give. | — | |
| HBP | Hit by pitch The batter is hit by a pitch outside the strike zone and takes first base. | — | What is HBP |
| SO / K | Strikeouts Plate appearances that end on strike three. | — | |
| SF | Sacrifice flies Fly outs that score a runner. Not an at-bat. | — | |
| SH | Sacrifice hits (bunts) Bunts that move a runner over while the batter is out. Not an at-bat. | — | |
| TB | Total bases Bases gained from hits only. | 1B + 2×2B + 3×3B + 4×HR | |
| XBH | Extra-base hits Doubles, triples and home runs. | 2B + 3B + HR | What is XBH |
| SB | Stolen bases Bases taken by a runner without the help of a hit, walk or error. | — | |
| CS | Caught stealing Times a runner was thrown out trying to steal. | — | |
| GIDP | Grounded into double play Ground balls that result in two outs. | — | |
| AVG | Batting average How often a batter gets a hit per at-bat. | H ÷ AB | Batting average calculator |
| OBP | On-base percentage How often a batter reaches base. | (H + BB + HBP) ÷ (AB + BB + HBP + SF) | OPS calculator |
| SLG | Slugging percentage Total bases per at-bat. Measures power. | TB ÷ AB | Slugging calculator |
| OPS | On-base plus slugging A quick measure of overall hitting. | OBP + SLG | OPS calculator |
| ISO | Isolated power Extra bases per at-bat. Strips out singles. | SLG − AVG | XBH and ISO |
| BABIP | Batting average on balls in play Batting average on balls that stay in the park. Shows luck and skill. | (H − HR) ÷ (AB − K − HR + SF) | BABIP calculator |
| OPS+ | Adjusted OPS OPS adjusted for ballpark and league. 100 is average. | — | |
| WAR | Wins above replacement Estimated wins a player adds compared with a freely available replacement player. | — |
Pitching Stats
| Abbr. | Stat and meaning | Formula | Learn more |
|---|---|---|---|
| G | Games Games a pitcher appeared in. | — | |
| GS | Games started Games the pitcher started. | — | |
| W | Wins Credited to the pitcher of record when his team takes the lead for good. | — | |
| L | Losses Credited to the pitcher who allows the go-ahead run that is never matched. | — | |
| SV | Saves Credited to a finishing pitcher who preserves a close win under set conditions, such as a lead of three runs or fewer in the last inning. | — | |
| HLD | Holds A reliever who enters a save situation, gets at least one out and leaves without losing the lead. | — | |
| IP | Innings pitched Outs recorded divided by three. 5.1 means 5⅓ innings. | Outs ÷ 3 | Partial innings explained |
| BF | Batters faced Total plate appearances against the pitcher. | — | |
| ER | Earned runs Runs that score without the help of an error or passed ball. | — | Earned vs unearned runs |
| ERA | Earned run average Earned runs allowed per nine innings. | 9 × ER ÷ IP | What is ERA |
| WHIP | Walks plus hits per inning pitched Baserunners allowed per inning, not counting hit batters. | (BB + H) ÷ IP | WHIP calculator |
| FIP | Fielding independent pitching ERA-like stat that uses only strikeouts, walks, hit batters and home runs. | (13×HR + 3×(BB+HBP) − 2×K) ÷ IP + constant | FIP calculator |
| K/9 | Strikeouts per nine Strikeout rate over nine innings. | 9 × K ÷ IP | |
| BB/9 | Walks per nine Walk rate over nine innings. | 9 × BB ÷ IP | What is BB/9 |
| K/BB | Strikeout-to-walk ratio Strikeouts divided by walks. Measures control and dominance. | K ÷ BB | K/BB ratio guide |
| QS | Quality start A start of at least 6 innings with 3 earned runs or fewer. | — | ERA and quality starts |
| CG | Complete game A game the starter finishes with no relief help. | — | |
| SHO | Shutout A complete game with no runs allowed. | — | |
| WP | Wild pitches Pitches too wild for the catcher to handle that let a runner advance. | — | |
| BK | Balks Illegal pitcher moves that let all runners advance one base. | — | |
| ERA+ | Adjusted ERA ERA adjusted for ballpark and league. 100 is average, higher is better. | — | ERA+ explained |
Fielding and Baserunning Stats
| Abbr. | Stat and meaning | Formula | Learn more |
|---|---|---|---|
| E | Errors Misplays that let a batter or runner advance when an average fielder would have made the play. | — | Hit vs error |
| PO | Putouts Outs a fielder records by catching, tagging or stepping on a base. | — | |
| A | Assists Throws or deflections by a fielder that help another fielder make an out. | — | |
| DP | Double plays Plays that record two outs. | — | |
| FPCT | Fielding percentage Share of chances a fielder handles without an error. | (PO + A) ÷ (PO + A + E) | |
| PB | Passed balls Catcher misses a pitch he should have caught and a runner advances. | — | |
| FC | Fielder's choice A fielder takes an out on a different runner. The batter reaches without a hit. | — | Hit vs fielder's choice |
| LOB | Left on base Runners who finish an inning on base without scoring. | — |
Team and Standings Stats
| Abbr. | Stat and meaning | Formula | Learn more |
|---|---|---|---|
| W-L | Win-loss record A team's wins and losses. | — | |
| PCT | Winning percentage Share of games won. | W ÷ (W + L) | |
| GB | Games back How far a team trails the leader in the standings. | ((W₁ − W₂) + (L₂ − L₁)) ÷ 2 | Magic number calculator |
| RS / RA | Runs scored / runs allowed Total runs a team scored and allowed. | — | |
| MN | Magic number Combined wins by the leader and losses by the chaser that clinch a spot. | — | Magic number calculator |
Counting Stats vs Rate Stats
Stats come in two types. Counting stats are totals, such as H, HR, RBI and K. They go up as a player plays more. Rate stats divide by chances, such as AVG, OBP, ERA and K/9. They tell you how well a player did per chance, so you can compare someone with 300 at-bats against someone with 600. When you compare players, use rate stats for quality and counting stats for volume.
Do the Stats Change at Other Levels?
The formulas are the same, but the numbers are scaled by the length of the game. A Little League ERA uses 6 innings and a high school ERA uses 7, instead of 9. Softball ERA uses 7. So never compare an ERA from one level straight to another. For how the game itself changes between levels, see how baseball works.
🎯 The Bottom Line
Learn the 10 most common codes first: AB, H, HR, RBI, BB, SO, AVG, OBP, SLG and ERA. They cover most of what you will see in a box score.
Then use the tools to check your own numbers. Try the free baseball and softball calculators.
Frequently Asked Questions
What does AB mean in baseball?
AB stands for at-bat. It is a plate appearance that counts toward batting average. Walks, hit by pitch, sacrifice bunts and sacrifice flies are not at-bats.
What does RBI mean in baseball?
RBI stands for runs batted in. A batter gets an RBI when his action, such as a hit, a sacrifice fly or a bases-loaded walk, causes a run to score.
What is the difference between AVG, OBP and SLG?
AVG is hits divided by at-bats. OBP is how often a batter reaches base, including walks and hit by pitch. SLG is total bases divided by at-bats, which measures power. Adding OBP and SLG gives OPS.
What does BB mean in a box score?
For a hitter, BB is the number of walks drawn. For a pitcher, BB is the number of walks allowed. It stands for base on balls.
What is the difference between ERA and WHIP?
ERA is earned runs allowed per nine innings. WHIP is walks plus hits per inning pitched. ERA measures runs, and WHIP measures how many runners a pitcher lets on base.
What does K mean in baseball?
K means strikeout. It is also written SO. Scorers use a backward K (ꓘ) for a strikeout looking, when the batter does not swing at strike three.
What is a good OPS in baseball?
An OPS around .700 is about average in MLB. A mark of .800 is good and .900 or higher is excellent. These are rough guides that change a little from season to season.