RBI Efficiency Calculator

RBI efficiency measures RBI against what an average hitter would get from the same chances

An RBI needs a runner on base ahead of the batter, so raw totals say as much about the lineup as about the hitter. This calculator sorts a hitter's plate appearances into eight base situations (bases empty, runner on 1st, 2nd, 3rd, 1st and 2nd, 1st and 3rd, 2nd and 3rd, bases loaded) and multiplies each by the RBI per plate appearance that the league's average hitter produced in that situation that season. The sum is the expected RBI. Actual RBI divided by expected RBI is the RBI efficiency, where 100% is a league-average hitter given the same chances.

Yordan Alvarez (HOU) drove in 106 runs in 692 plate appearances in the 2026 MLB regular season. A league-average hitter in his base situations would have driven in 68.8, so his RBI efficiency is 154%. His +37.2 over expectation was the best among the 135 MLB hitters with enough plate appearances to qualify. He did it with fewer chances than average: 0.54 runners on base per plate appearance against a league average of 0.61. On chances alone he was 9.5 RBI behind an average hitter.

Why raw RBI totals mislead

RBI tie directly to runs scored, but lineup spot and the hitters batting ahead of you decide how many chances you get. Putting expected RBI next to the total separates cases like these.

• Comparing hitters with different chances: among 2026 MLB qualified hitters, the opportunity effect runs from +13.2 (Seiya Suzuki, CHC) to −15.1 (JJ Wetherholt, STL), a gap of 28.3 RBI that has nothing to do with skill.
• RBI leader versus most efficient: Alec Burleson (STL) led MLB with 116 RBI, which is 144% of his expected 80.5. Alvarez had 10 fewer RBI but a higher efficiency, 154%, because Burleson had 0.73 runners on base per plate appearance and Alvarez only 0.54.
• Judging a low RBI total: Steven Kwan (CLE) had 32 RBI against an expected 60.7. Of the gap between his total and an average hitter with average chances, 11.4 RBI comes from fewer runners on base (opportunity effect) and 28.7 from the bat (hitting effect). A low total does not by itself mean a poor run producer.
• When batting average with runners in scoring position falls short: that stat counts hits only. Sacrifice flies, bases-loaded walks, RBI groundouts, and the number of runners a hit scores are left out, and a runner on 2nd is treated the same as bases loaded.

How to use it

1. Choose the benchmark league (KBO or MLB) and the season (2026 or 2025). Expected RBI is computed from that league and season's RBI per plate appearance in each situation.
2. Pick a qualified hitter under Load a player to fill the eight cells and the home run box. The lists hold 135 MLB hitters for 2026 and 145 for 2025, plus 49 KBO hitters for 2026 and 43 for 2025, ordered by RBI.
3. To enter another record by hand, use the 'Bases Occupied' table in a Baseball-Reference player split for MLB. Copy PA and RBI from the rows ---, 1--, -2-, --3, 12-, 1-3, -23 and 123 (bases empty through bases loaded). For KBO, open the player's detail page on the KBO records site (koreabaseball.com) and use the first table of the situation tab. That table has no plate-appearance column, so enter at-bats + walks + hit-by-pitch as PA and copy the RBI. Leave a situation blank if there is no record and it counts as 0.
4. Enter the full-season home run total in the home run box and the calculator also gives OBI%, the share of runners on base that the hitter drove in.
5. Read RBI efficiency, the gap to expected RBI and OBI% at the top. The RBI flow steps split the total into an opportunity effect and a hitting effect. On the situation bars, the middle tick is the league average, and a bar past the tick means more RBI per plate appearance than average in that situation. The plane at the bottom shows where the entry sits among the same season's qualified hitters and which hitters are closest.

How it is calculated

1. League RBI per PA in situation s = all RBI in situation s that season ÷ all plate appearances in situation s
2. Expected RBI = Σ(hitter's PA in situation s × league RBI per PA in s), rounded to one decimal
3. RBI efficiency = actual RBI ÷ expected RBI × 100
4. Average chances = total PA × league RBI per PA overall; opportunity effect = expected RBI − average chances; hitting effect = actual RBI − expected RBI
5. OBI% = (RBI − HR) ÷ runners on base, where runners on base = Σ(PA in situation s × runners in that situation). This is the definition of OBI% (Others Batted In Percentage) from Baseball Prospectus. Some sites call the same ratio RBI percentage: 100 × (RBI − HR) ÷ runners on.

Here is the calculation for Yordan Alvarez, 2026 MLB.

RBI efficiency is 106 ÷ 68.8 = 154%. Average chances are 692 × .1132 = 78.3, so the opportunity effect is 68.8 − 78.3 = −9.5 and the hitting effect is 106 − 68.8 = +37.2. Subtracting his 42 home runs leaves 64 RBI that drove in other runners. Divided by 377 runners on base (203 on 1st, 119 on 2nd, 55 on 3rd), his OBI% is 17.0%, against a league figure of 13.6%.

With the bases empty, every RBI is a solo home run. Alvarez had 24 there against an expected 12.6, which is +11.4 of his +37.2. The other big gap is the 11 plate appearances with the bases loaded, where he drove in 20 runs against an expected 7.5 (+12.5). Differences are rounded cell by cell, so the eight rounded differences can occasionally miss the total by 0.1.

League benchmark: RBI per plate appearance by base situation

These are the league values behind expected RBI. KBO is the sum of every player in the records site's runner-situation table, and MLB is the sum of the 30 teams in the official stats. Both totals match the league's RBI and home run totals for the season exactly.

Part of why KBO looks higher than MLB for a runner on 3rd, 1st and 3rd, 2nd and 3rd, and bases loaded is how plate appearances are counted. The KBO table has no sacrifice flies or sacrifice bunts, so PA is at-bats + walks + hit-by-pitch, while MLB uses official PA. Count MLB 2026 the KBO way, without sacrifices (and catcher's interference), and a runner on 3rd moves from .338 to .359, 1st and 3rd from .437 to .476, and bases loaded from .686 to .747. Use each league only as the benchmark for records in that same league, not to compare the two leagues with each other.

2026 qualified hitters side by side

The first six rows are MLB and the last two are KBO, each calculated against its own league and season. Burleson (116 RBI) and Alonso (113) were the top two in MLB, and Alvarez, with 106, is ahead of both on efficiency. Seiya Suzuki shows the reverse: he had the largest opportunity effect of all 135 MLB qualified hitters (+13.2), so nearly all of his 86 RBI is what an average hitter would have collected with the same runners on base, and his hitting effect is only +1.1. Kwan is low on both counts, but his hitting effect (−28.7) is far bigger than his opportunity effect (−11.4).

How it differs from 'RBI ÷ plate appearances with runners in scoring position'

Dividing RBI by plate appearances with a runner in scoring position is sometimes called RBI efficiency too, but it mixes two different bases.

• The numerator includes RBI that did not come with a runner in scoring position, such as solo home runs and runs driven in from 1st only. Shrinking only the denominator to scoring position inflates the figure for home run hitters.
• A grand slam is four RBI in one plate appearance, so the ratio can pass 100%. Alvarez had 11 plate appearances with the bases loaded and 20 RBI there, or 1.818 per plate appearance.
• A runner on 2nd and bases loaded are not the same chance. League RBI per plate appearance in MLB 2026 is .170 with a runner on 2nd and .686 with the bases loaded, more than four times as much, yet both are one plate appearance in the scoring-position count.

The calculator still shows RBI per plate appearance with runners in scoring position on a reading line, next to the league value (.317 for MLB 2026), for reference. Efficiency itself comes from the expected RBI in each situation.

Common mistakes

• Entering at-bats for an MLB record: the MLB benchmark counts official plate appearances. At-bats leave out walks, hit-by-pitch and sacrifices, which makes expected RBI too low and efficiency too high. KBO is the reverse, because its table has no PA column and you enter at-bats + walks + hit-by-pitch.
• Entering only home runs hit with runners on: the home run box takes the full-season total. If the total is smaller than the RBI with the bases empty (all solo home runs), an error message appears.
• Counting runs scored on errors or double plays as RBI: under the official MLB glossary, a run that scores on an error or a double play is not an RBI. Copy the numbers from the stats site as they are.
• 'Correcting' a KBO total that differs from official PA: the situation table has no sacrifices, so its total is smaller by the number of sacrifice flies and bunts (Kim Do Yeong: 593 official PA, 588 in the table). The league benchmark is built the same way, so leave it alone.
• Picking a different league or season: the same record gives a different expected RBI under a different benchmark. Alvarez's 2026 line against the MLB 2025 benchmark gives an expected 70.1 and 151%. Against the KBO 2026 benchmark it gives 69.2 and 153%.
• Comparing a few weeks with a full season: cells such as bases loaded or 2nd and 3rd hold only 10 or so plate appearances in a season, and one hit moves the RBI per plate appearance a lot. A few weeks of data makes efficiency swing widely, so use full-season records.

Limits

• Outs are not split out. A runner on 3rd with no outs and with two outs are very different chances, but the KBO records site shows runner situation and outs separately, so the calculation uses the eight base situations alone.
• It does not adjust for runner speed, batted-ball luck, ballpark or opposing pitchers. A hitter who bats behind fast runners gets more RBI from the same hit.
• It ignores score and inning, so it is not a measure of clutch hitting in close games.
• The KBO benchmark excludes sacrifices from plate appearances, so a hitter with many sacrifice flies reads a little high on efficiency and OBI%.
• League benchmarks and qualified hitters are the final 2025 and 2026 regular-season records checked on 2026-10-23. Postseason games are not included.
• Values you enter are not sent to a server and are calculated only in this browser. They are added to the address only when you edit a value or press Copy link.

As of the definition of OBI% was checked on 2026-10-23 against the Baseball Prospectus glossary, and the RBI rule against the MLB glossary. League benchmarks and qualified hitter records were calculated the same day from the KBO records site and MLB official stats (Stats API) for the regular season.

Sources

• 01KBO records: hitter situation splits2025 and 2026 regular season by bases empty, 1st, 2nd, 3rd, 1st and 2nd, 1st and 3rd, 2nd and 3rd, loaded: at-bats, hits, home runs, RBI, walks, hit-by-pitch (no PA or sacrifice columns)
• 02KBO records: hitter basic statsQualified regular-season hitters (446 PA or more): 49 in 2026 and 43 in 2025, with PA, RBI, home runs, sacrifice bunts and sacrifice flies
• 03MLB Stats API: situation codesRunner situation codes r0 (Bases Empty), r1, r2, r3, r12, r13, r23 and r123 (Bases Loaded), team and player statSplits for the 2025 and 2026 regular seasons
• 04MLB Stats API: qualified hitters, season stats135 hitters in 2026 and 145 in 2025, with situation PA, RBI and HR totals matched to the season line
• 05Baseball Prospectus: Glossary (OBI, OBI%)OBI = RBI − HR; OBI% = the percentage of all runners on base who were batted in
• 06Baseball-Reference: 2025 Situational BattingDefinitions of BR (runners on base at the plate appearance), BRS (runners who scored, not always on an RBI) and BRS%, plus PA and RBI in the player split 'Bases Occupied' table
• 07MLB Glossary: Runs Batted In (RBI)A run that scores on an error or a double play is not an RBI; a batter who makes an out can still get an RBI if a run scores

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