Baseball Runs Created (RC) Calculator

Runs created estimates a hitter's contribution from his own stat line

Runs Created (RC) is an offensive stat invented by Bill James. It is calculated as On base (A) × Advance (B) ÷ Chances (C). RBIs and runs scored depend on who bats before and after a player, but RC uses only the hitter's own hits, walks, total bases and steals to estimate how many of his team's runs he created. RC/27 turns that total into runs per 27 outs: the number of runs a lineup of nine copies of this hitter would score in one game.

Take Yordan Alvarez of the Houston Astros in 2026 (567 AB, 179 H, 34 2B, 1 3B, 42 HR, 109 BB with 33 intentional, 11 HBP, 5 SF, 1 SB, 0 CS, 7 GDP). Put that line into the technical formula that Baseball-Reference uses and you get RC 154.8 and RC/27 10.45. That is the highest RC among the 135 qualified MLB hitters, and 74.0 runs more than the average MLB hitter would create with the same 692 chances (80.8). A lineup of nine Alvarezes would score 10.45 runs per 27 outs, 1.98 times the 5.27 of the Chicago Cubs, the highest-scoring MLB team per 27 outs in 2026.

Why look at RC

Batting average, home runs and RBIs each show only a slice of an offense, and RBIs carry credit that belongs to other hitters. RC answers a few common questions in one unit, runs.

• Judging value from a hitter's own numbers: RBIs need runners on base and runs scored need teammates to drive you in. RC uses only your own line, so players on different teams and in different lineup spots can be compared on one scale.
• Comparing on-base and power styles: Pete Crow-Armstrong (Chicago Cubs) hit 45 home runs and stole 41 bases for an RC of 145.2, only 9.6 behind Alvarez, whose 109 walks and 42 home runs gave him 154.8. At the other end, Chandler Simpson (Tampa Bay Rays) hit no home runs but had 175 hits and 46 steals for an RC of 71.3.
• Sorting out amateur or recreational stats: at-bats, hits and walks are enough to start. RC/27 lets you compare players with different numbers of games, and you can set the result next to the runs per 27 outs of big-league teams.
• Estimating team scoring: RC computed from a whole team's totals lands close to its real runs. The technical formula applied to the 2026 MLB totals gives 21,463.6 runs against 21,769 actually scored, 1.4% low.

How to use it

1. Pick the league to compare with, MLB or KBO. The league average, the qualified-hitter ranking and the team bars switch to that league's 2026 regular season.
2. Enter a season line in the batting-line form. Hits should be all hits, including doubles, triples and home runs, and walks should include intentional walks. Blank boxes count as 0, and plate appearances and outs (the RC/27 denominator) fill in on their own.
3. In the result, check RC, RC/27, how On base (A), Advance (B) and Chances (C) were calculated, and how far the hitter is from the average hitter with the same chances.
4. Under "Formula" compare the technical, stolen base and basic formulas. The plane, bars and ranking redraw for the one you select.
5. On the plane, compare the rectangle area (RC per chance) with the league-average rectangle and the dots for qualified hitters. In the bar chart, see where a lineup of nine of this hitter would rank among the league's teams. The example buttons load the top-RC hitter, the stolen-base leader, an amateur season and Barry Bonds in 2004. Copy result and Copy link let you reopen the same calculation.

How it is calculated

All three formulas have the form RC = A × B ÷ C. A counts times on base, B measures how far the runners were advanced, and C counts chances. Only the stats that go into each part differ.

Total bases are H + 2B + 2 × 3B + 3 × HR. RC/27 is RC × 27 ÷ outs, and outs are counted as AB − H + SH + SF + CS + GDP. Here is Alvarez's 2026 line run through the technical formula.

The rectangle's area is RC per chance

RC = A × B ÷ C can be rewritten as C × (A ÷ C) × (B ÷ C). Put A ÷ C (a number much like on-base percentage) on the horizontal axis and B ÷ C (much like slugging) on the vertical axis. The rectangle from the origin to a hitter's dot then has an area equal to his RC per chance, and multiplying by his chances gives RC. Alvarez comes out at .422 wide × .530 tall = .224, which is 1.91 times the MLB average of .117.

Because area is width times height, two hitters with the same area can look very different: an on-base hitter makes a wide rectangle, a power hitter a tall one. Dots with the same area lie on a hyperbola, and the grey curves on the plane join points with the same RC per chance, such as .100, .150 and .200. A qualified hitter above the curve through your dot (the orange dashed line) has a higher RC per chance.

How the three formulas differ

The basic formula uses only hits, walks and total bases, so the more a hitter steals, gets caught, grounds into double plays, sacrifices or gets hit by pitches, the more it drifts from the technical formula. Among 2026 qualified MLB hitters the biggest gap between the two belonged to Pete Crow-Armstrong (+15.3).

Simpson is the exception. The technical formula also subtracts his 6 double plays from A (181 against 187), adds his 9 sacrifice bunts and 6 sacrifice flies to C (612 against 597) and weights a steal at .52 instead of .55, so the stolen base formula comes out slightly higher (71.5 against 71.3). Baseball-Reference says it uses the technical formula when stolen base and caught stealing data exist. If there are no steal data it falls back to a basic formula, (H + BB + HBP) × TB ÷ (AB + BB + HBP + SF), and if hit-by-pitch, intentional walk, sacrifice and double-play data are missing it uses the stolen base formula. So the same player can have a different RC depending on the site and the era. The basic formula here is the original that the MLB Glossary describes: TB × (H + BB) ÷ (AB + BB).

How close RC is to actual runs

Computing RC from a team's totals and comparing it with the runs it really scored shows how good a formula is. Below are the 2026 regular-season league totals put through all three formulas.

The technical formula was within 1.4% in both leagues, while the stolen base and basic formulas, which leave out hit-by-pitch and sacrifices, came in 5% to 7% low. Team by team, the technical RC missed actual runs by anywhere from −5.2% (Hanwha) to +3.7% (Kiwoom) in the KBO, and from −7.5% (St. Louis) to +3.4% (Kansas City) in MLB. RC does not know the order in which hits came or who was on base, so a team that hit well with runners on will score more than its RC says.

RC/27 is the runs per game of a nine-man lineup of this hitter

RC grows with plate appearances, so to compare hitters with different playing time use RC/27. Twenty-seven outs is what a team makes in a nine-inning game, so read RC/27 as "how many runs would nine of these hitters score in a game?" The calculator's bar chart sets this number among the actual runs per 27 outs of the 2026 league teams (team runs × 27 ÷ outs counted the same way).

The qualified median is above the league average because the hitters who play enough to qualify tend to be the good ones. Of the 135 qualified MLB hitters in 2026, 41 had an RC/27 below the league's 4.47, and in the KBO it was 16 of 49 below 5.03 (comparing unrounded values). The RC leader and the RC/27 leader are not always the same person: in the KBO, Austin Dean (LG) led in RC with 152.2 but Koo Ja Wook led in RC/27, while in MLB Alvarez led both, with Pete Crow-Armstrong second in each (RC 145.2, RC/27 8.43).

RC overstates truly great hitters

Because A and B are multiplied, RC assumes a lineup made entirely of that same hitter. A hitter who is great at both getting on base and hitting for power is treated as if he always had a hitter just like himself on base ahead of him, which gives a figure larger than his real contribution. The English Wikipedia article on runs created, following Bill James's own discussion, says this overrating shows up for hitters such as Babe Ruth, Ted Williams and Barry Bonds.

Bonds in 2004 (373 AB, 135 H, 45 HR, 232 BB, 120 of them intentional) has a technical RC of 203.4 and an RC/27 of 22.23. That would be nine Bonds scoring 22 runs per 27 outs, when the best 2026 MLB team, the Cubs, scored 5.27. The same effect appears when you add one more event. One more home run adds 1.59 to the RC of Michael Busch (Chicago Cubs), the median qualified hitter in MLB in 2026, 2.00 to Alvarez and 2.62 to Bonds in 2004. Bill James's 2002 version of RC reduces the problem by placing the hitter inside a real team's lineup and adding a bonus for hitting with runners in scoring position, but it needs situational and team-wide data that this calculator does not take.

Common mistakes

• Entering only singles in the hits box: hits include doubles, triples and home runs. If you enter only singles, doubles + triples + home runs can exceed hits, which gives an error or a too-low RC.
• Subtracting intentional walks from walks first: the walks box is total walks, intentional ones included. The technical formula takes the intentional walks out of B for you.
• Adding sacrifice bunts and flies to at-bats: sacrifices are not at-bats. Check that the plate appearances shown match your scorebook's total (AB + BB + HBP + SF + SH).
• Comparing RC from different formulas: Alvarez is 154.8 with the technical formula and 145.3 with the basic one. When you compare with another site, first make sure you use the same formula.
• Adding strikeouts to the outs for RC/27: strikeouts are already inside AB − H. Outs are AB − H + SH + SF + CS + GDP.
• Trusting RC/27 from a small sample: the amateur example (60 plate appearances) has an RC/27 of 9.30, which would be near the top of MLB, but a few hits move it a lot. With few plate appearances, look at the raw stats too.

Limits

• No adjustment for ballpark or league run environment. A hitter-friendly park or a high-scoring year pushes the number up as is. To compare across parks and leagues, use wRC+ or OPS+.
• Bill James's 2002 version of RC (team context and a bonus for hitting with runners in scoring position) is not included.
• Defense, position and baserunning beyond steals (taking an extra base, being thrown out on the bases) are not counted. Pickoffs and baserunning outs are not in the outs, and neither are times on base by error or catcher's interference.
• League averages, rankings and the team bars use 2026 regular-season stats. MLB figures come from the official MLB Stats API and KBO figures from the KBO records site. No data from Japan's NPB is included, so a hitter cannot be compared with NPB averages.
• League RC is computed by putting team totals into the formula. Baseball-Reference adds up the individual RCs for a team, so its figure can differ slightly.
• The qualified-hitter ranking compares values rounded to the digits shown (one decimal for RC, two for RC/27), and does not count a hitter whose 13 boxes match the line you entered, such as an example you loaded.

As of the formulas were checked on 2026-10-23 against the Baseball-Reference batting glossary, the MLB Glossary and Wikipedia (English and Japanese). League totals and qualified hitters were calculated the same day from the MLB Stats API and the KBO records site for the 2026 regular season.

Sources

• 01Baseball-Reference — Batting GlossaryRuns Created: the technical formula when steal data exist, the basic and stolen base formulas when data are missing, and team RC as the sum of player RC
• 02MLB Glossary — Runs Created (RC)The most basic formula, TB × (H + BB) ÷ (AB + BB), created by Bill James
• 03Wikipedia — Runs createdBasic, stolen base and technical formulas, the 2002 version, RC per 27 outs, overrating of hitters with very high on-base and power
• 04Wikipedia (Japanese) — RC (野球)RC27 = 27 × RC ÷ (AB − H + SH + SF + CS + GDP)
• 05KBO Records — Team hitting (Basic1, Basic2)2026 regular season, 10 teams: runs, at-bats, hits, total bases, walks, intentional walks, HBP, sacrifices, GDP
• 06KBO Records — Team baserunning2026 regular season, 10 teams: stolen bases and caught stealing
• 07KBO Records — Player hitting and baserunning2026 regular season, 49 qualified hitters (446 PA): batting (Basic1, Basic2), steals and caught stealing
• 08MLB Stats API — 2026 team hitting30 teams: runs, hitting, steals, caught stealing, GDP
• 09MLB Stats API — 2026 qualified hitters135 qualified hitters (502 PA)
• 10MLB Stats API — Barry Bonds year by year2004: 373 AB, 135 H, 45 HR, 232 BB, 120 IBB, 9 HBP, 6 SB, 1 CS, 5 GDP

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