Basketball Game Score (GmSc) Calculator

Background.

Game Score is John Hollinger's answer to a question that box scores are bad at answering on their own: how good was that game, really? A 30-point night on 30 shots is not the same as a 30-point night on 18 shots, and a 12-point, 14-rebound, 6-assist line with no turnovers may be worth more than either. Game Score compresses all eleven counted box-score categories into a single number on a scale deliberately chosen to feel familiar — Basketball-Reference states plainly that 10 is an average performance and 40 an outstanding one, which is roughly the scale of points scored.

The formula, published verbatim by Basketball-Reference, is GmSc = PTS + 0.4 x FG - 0.7 x FGA - 0.4 x (FTA - FT) + 0.7 x ORB + 0.3 x DRB + STL + 0.7 x AST + 0.7 x BLK - 0.4 x PF - TOV. This calculator implements it exactly, and additionally splits the result into its positive and negative halves so you can see which side of the ledger drove the number, reports a per-36-minute rate so bench and starter performances can be compared, and attaches a plain-language band.

The coefficients repay a moment's attention, because they encode a whole theory of basketball value. A field goal attempt costs 0.7 whether it goes in or not, which is why volume without efficiency drags a Game Score down hard. A steal is worth a full point and a turnover costs a full point, treating the two as exact mirror images of each other. An offensive rebound is worth 0.7 and a defensive rebound only 0.3, because an offensive board creates a possession that was about to belong to the other team while a defensive board mostly secures one your team was going to get anyway. And a made field goal receives a small +0.4 bonus on top of the points it already produced, which rewards accuracy rather than merely scoring.

Unlike Player Efficiency Rating — Hollinger's other and far better-known metric — Game Score needs nothing beyond one player's line in one game. No team totals, no league constants, no pace adjustment, no standardisation. That makes it the right tool for exactly the situations where PER is the wrong one: rating a single performance, comparing two nights, or settling an argument about a box score in front of you. The most famous single result is Kobe Bryant's 81-point game against Toronto in January 2006, which produced a Game Score of 63.5 — the second-highest ever recorded, behind only Wilt Chamberlain's 100-point game.

What is basketball game score calculator?

Game Score is a single-game productivity index for basketball players, created by John Hollinger and published by Basketball-Reference as GmSc. It is a fixed-coefficient linear combination of the eleven quantities a standard box score records: points, field goals made and attempted, free throws made and attempted, offensive and defensive rebounds, assists, steals, blocks, personal fouls and turnovers. Each event carries a weight — points at 1.0, made field goals at +0.4, field goal attempts at -0.7, missed free throws at -0.4, offensive rebounds at +0.7, defensive rebounds at +0.3, steals at +1.0, assists at +0.7, blocks at +0.7, personal fouls at -0.4 and turnovers at -1.0 — and the weighted sum is the Game Score. Basketball-Reference describes its purpose as giving 'a rough measure of a player's productivity for a single game' on a scale 'similar to that of points scored', with 40 an outstanding performance and 10 an average one. Because the coefficients are fixed rather than derived from a season's league averages, Game Score requires no context at all beyond the line itself: no team totals, no league constants, no pace figure. That is both its strength and its limitation. It travels anywhere and computes in seconds, but it cannot adapt to a different scoring environment, it cannot see anything the box score does not record — defensive positioning, screens, gravity, shot contests that never became attempts — and it does not adjust for minutes unless you ask it to. It is best used as a quick single-game comparator, not as a season-long evaluation tool; for that, Hollinger's Player Efficiency Rating exists.

How to use this calculator.

1. 01Take one player's line from one box score. Game Score is designed for a single game, though the arithmetic works on any span you give it.
2. 02Enter points, then the makes and attempts for field goals and free throws. The calculator checks that the points total is consistent with the makes — a line with 8 field goals and 4 free throws must produce between 20 and 28 points — and will tell you if it is not.
3. 03Enter offensive and defensive rebounds separately rather than a total, because the formula values them very differently: +0.7 against +0.3.
4. 04Enter assists, steals, blocks, personal fouls and turnovers.
5. 05Enter minutes played as a decimal — 41 minutes 56 seconds is 41.93. This affects only the per-36 rate; the Game Score itself is not a per-minute statistic.
6. 06Read the primary result against the two published anchors: 10 is average, 40 is outstanding. Between those, roughly 15 is a good starter's night, 20 is the best player on the floor, and 30 is a superstar performance.
7. 07Look at the positive and negative components separately when a number surprises you. A 25-point night that grades out at 12 is almost always a story about the negative side: 24 field goal attempts alone cost 16.8 points of Game Score.

The formula.

The formula is GmSc = PTS + 0.4 x FG - 0.7 x FGA - 0.4 x (FTA - FT) + 0.7 x ORB + 0.3 x DRB + STL + 0.7 x AST + 0.7 x BLK - 0.4 x PF - TOV, exactly as Basketball-Reference publishes it.

The scoring terms. Points enter at their face value, then made field goals receive an extra +0.4 each. That bonus is a reward for accuracy rather than for scoring: two players who each score 20 points get the same base credit, but the one who needed fewer makes to do it — more threes, more free throws — gets less of the bonus, while the one who converted more shots gets more. Against that, every field goal attempt costs 0.7 regardless of outcome. The net effect for a made two-pointer is 2 + 0.4 - 0.7 = +1.7, and for a missed shot it is -0.7. The break-even field goal percentage from twos alone is therefore 0.7 / 2.4 = 29.2%, which sounds low until you remember that everything else in a possession is being counted elsewhere.

The free throw terms. Made free throws are already inside the points total, so the formula charges only for misses at -0.4 each. A 10-for-12 night from the line costs 0.8; a 4-for-12 night costs 3.2.

The rebounding terms. Offensive rebounds are worth +0.7 and defensive rebounds only +0.3. The reasoning is possession value: an offensive rebound takes back a possession that was about to become the other team's, while a defensive rebound mostly secures one your team was going to get anyway — roughly three quarters of missed shots are rebounded by the defence. The 0.7-to-0.3 ratio is a rough encoding of that asymmetry.

The playmaking and defensive terms. An assist is +0.7 — substantial, but less than the shooter receives for the basket itself. A steal is +1.0, the largest single-event credit in the formula, because a steal ends an opponent's possession and starts one of your own. A block is +0.7, less than a steal, because a blocked shot may still be recovered by the offence. A turnover is -1.0, an exact mirror of the steal. A personal foul is -0.4.

The interpretive bands. Basketball-Reference publishes only two reference points: 40 is an outstanding performance and 10 is an average one. The labels this calculator attaches between and beyond those anchors — modest, very good, excellent, superstar — are an interpolation between the two published points, offered as a reading aid rather than as league-defined thresholds. Treat the 10 and 40 boundaries as sourced and everything else as convenience.

What Game Score cannot do. It has no league context, so a 20 in a 1970s low-scoring environment and a 20 today are not strictly comparable. It has no pace adjustment. It cannot see defence beyond steals, blocks and defensive rebounds. And it is not a per-minute statistic, so a 25-minute performance and a 40-minute performance are compared on raw output unless you use the per-36 figure reported alongside.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Basketball-Reference.com Glossary, entry 'GmSc': "Game Score; the formula is PTS + 0.4 * FG - 0.7 * FGA - 0.4*(FTA - FT) + 0.7 * ORB + 0.3 * DRB + STL + 0.7 * AST + 0.7 * BLK - 0.4 * PF - TOV. Game Score was created by John Hollinger to give a rough measure of a player's productivity for a single game. The scale is similar to that of points scored, (40 is an outstanding performance, 10 is an average performance, etc.)." Source of both the formula and the two interpretive anchors used on this page.
2. [2]Basketball-Reference.com box score, Toronto Raptors at Los Angeles Lakers, 22 January 2006 — Kobe Bryant's 81-point line (81 PTS, 28-46 FG, 18-20 FT, 2 ORB, 4 DRB, 2 AST, 3 STL, 1 BLK, 1 PF, 3 TOV, 41:56 MP) with the published game_score of 63.5 used to verify this implementation.
3. [3]Sports Reference LLC, Basketball Glossary knowledge-base article — the publisher's own maintained copy of the Game Score definition and formula.
4. [4]Basketball-Reference.com, 'Calculating PER' — establishes the attribution of both Game Score and Player Efficiency Rating to John Hollinger and documents the substantial machinery (team totals, league constants, pace adjustment, standardisation) that PER requires and Game Score deliberately does not.