Effective Field Goal Percentage (eFG%) Calculator

Background.

Effective field goal percentage (eFG%) is the shooting percentage that stops pretending a made three-pointer and a made lay-up are the same event. Conventional field goal percentage divides makes by attempts and treats every make identically, which was a defensible simplification in 1978 and has been misleading ever since the NBA painted a three-point line in 1979-80. eFG% fixes it with the smallest possible correction: it credits a made three as 1.5 makes, because three points is 1.5 times two points. The formula, published verbatim by both the NBA's official stat glossary and Basketball-Reference, is (FG + 0.5 x 3P) / FGA.

This calculator takes the three numbers you can read straight off any box score — field goals made, field goals attempted, and three-pointers made — and returns eFG%, the conventional FG% beside it for contrast, the raw points you produced from the floor, your points per field goal attempt, and the exact number of percentage points the three-point adjustment added. Everything is computed with arbitrary-precision decimal arithmetic and rounded only at the final step, so the number matches what the league publishes rather than drifting by a rounding error.

The reason this one statistic matters more than almost any other in modern basketball is that Dean Oliver, in Basketball on Paper, identified shooting as the single largest of his Four Factors of basketball success and weighted it at roughly 40 percent — and the shooting factor is measured by eFG%, not FG%. Teams that win the eFG% battle win the overwhelming majority of games. That is also why the entire structural change to NBA offence over the last fifteen years — the disappearance of the long two, the explosion in three-point volume, the corner three as a designed shot — is legible in eFG% and invisible in FG%. A team that shifts a thousand shots from the long two to the corner three will see its FG% fall and its eFG% rise, and it will score more points. FG% cannot tell you that; eFG% can.

A concrete illustration, taken from Basketball-Reference's own glossary entry: Player A goes 4-for-10 with two threes, Player B goes 5-for-10 with none. Player B has the better FG% (50.0 % against 40.0 %), but both scored exactly 10 points from the floor on exactly 10 shots. eFG% correctly rates them identically at 50.0 %. That is the whole idea, and it is the reason a 34 % three-point shooter (eFG% 51.0 %) is a more efficient scorer than a 50 % mid-range shooter (eFG% 50.0 %) even though one of those numbers looks catastrophic and the other looks respectable.

Below the calculator you will find the derivation of the 0.5 coefficient, the exact boundary at which a three becomes the better shot, how eFG% differs from true shooting percentage (which folds free throws in and answers a slightly different question), what counts as a good eFG% at NBA, WNBA, NCAA and high-school level, the pre-1980 caveat, and how eFG% feeds into Dean Oliver's Four Factors framework. The worked example runs the 2023-24 Boston Celtics through the formula by hand and confirms the result against the .578 that Basketball-Reference publishes for that team.

What is effective field goal percentage calculator?

Effective field goal percentage is a shooting-efficiency statistic that adjusts conventional field goal percentage for the fact that a three-point field goal is worth one more point than a two-point field goal. Its formula is (FG + 0.5 x 3P) / FGA, where FG is field goals made, 3P is three-point field goals made, and FGA is field goal attempts. Because 3P is a subset of FG, a made three is effectively counted 1.5 times in the numerator, while a made two is counted once — precisely the ratio of their point values. The statistic is defined identically by the NBA's official stat glossary and by Basketball-Reference, and it is the shooting component of Dean Oliver's Four Factors of Basketball Success, the framework that assigns shooting roughly 40 percent of the explanatory weight for winning basketball games. eFG% is a rate, not a count: it says nothing about volume, so a player who takes two shots a game can post an enormous eFG% without contributing much. It deliberately ignores free throws, which is what distinguishes it from true shooting percentage (TS% = PTS / (2 x (FGA + 0.44 x FTA))). eFG% therefore answers 'how efficiently does this player or team shoot the ball from the floor?', while TS% answers 'how many points does this player or team generate per scoring attempt of any kind, including trips to the line?'. Both are useful; they are not interchangeable. eFG% can exceed 100 percent — a player who goes 10-for-10 from three has an eFG% of 150 percent — which surprises people the first time they see it but is arithmetically correct, since that player produced 3.0 points per shot and eFG% is exactly half of points per shot. Before the 1979-80 NBA season there was no three-point line, so 3P is zero for every earlier season and eFG% is identical to FG% for all historical players from that era.

How to use this calculator.

1. 01Enter field goals made (FG). This is every made shot from the floor, twos and threes together — the first number in a '9-20' shooting line. Do not include free throws; they are not field goals.
2. 02Enter field goal attempts (FGA), the second number in the shooting line. If a shooting foul sent a player to the line before the shot was released, that trip is not a field goal attempt; if the shot went up and missed, it is.
3. 03Enter three-pointers made (3P). This is already part of FG, so the calculator will reject a value larger than FG. If you are working with a pre-1980 NBA season, enter 0 and eFG% will equal FG%.
4. 04Read the primary result. A rough 2023-24 NBA scale: below 50% is poor, 52-55% is average, 57%+ is elite for a team and outstanding for a high-volume perimeter player. The 2023-24 league average was .547.
5. 05Compare the primary result with the conventional FG% shown beside it. The gap is the three-point bonus — it is what your shot selection is worth, and it is exactly 0.5 x 3P / FGA.
6. 06Use points per field goal attempt when you want to argue about shot selection rather than percentages. It is simply twice eFG%, and it makes the comparison to an alternative shot obvious: a 40% three-point shooter produces 1.20 points per attempt, which beats any two-point shot converted at less than 60%.
7. 07For team analysis, run the same calculation on your opponent's totals. The difference between your eFG% and theirs is the single most predictive of Dean Oliver's Four Factors.

The formula.

The formula is eFG% = (FG + 0.5 x 3P) / FGA.

Where the 0.5 comes from. Start with points rather than makes. Points scored from the floor equal 2 x (two-point makes) + 3 x (three-point makes). Since FG counts all makes, two-point makes = FG - 3P, so points from the floor = 2 x (FG - 3P) + 3 x 3P = 2 x FG + 3P. Divide by attempts to get points per field goal attempt: (2 x FG + 3P) / FGA. Factor out the 2: 2 x (FG + 0.5 x 3P) / FGA. The bracket is exactly eFG%. So eFG% is nothing more or less than half of points per shot, rescaled onto the familiar percentage axis where an average two-point-only shooter converting 50 percent scores 1.00 point per shot. The 0.5 is not a fudge factor or a regression coefficient — it is 3/2 minus 1, the extra half-make that a three-pointer is worth.

The break-even point. A three-point attempt at percentage p3 produces 3 x p3 points; a two-point attempt at percentage p2 produces 2 x p2 points. The three is the better shot whenever 3 x p3 > 2 x p2, i.e. whenever p3 > (2/3) x p2. At a league-average two-point percentage of about 54.5 percent (2023-24 NBA), the break-even three-point percentage is 0.667 x 54.5 = 36.3 percent. Shoot better than that from deep and every three you take instead of an average two adds points. This single inequality explains the last fifteen years of NBA shot-chart evolution more completely than any other piece of arithmetic.

What eFG% excludes. Free throws are not in the formula at all. A player who draws six shooting fouls per game and shoots 90 percent from the line generates a lot of points that eFG% simply does not see. That omission is deliberate: eFG% is designed as a clean measure of shooting from the floor. If you want the version that folds in free throws, use true shooting percentage, TS% = PTS / (2 x (FGA + 0.44 x FTA)), which uses the empirically derived 0.44 coefficient to convert free throw attempts into shot-equivalent possessions.

Rounding and precision. The calculator performs every step in arbitrary-precision decimal arithmetic and rounds only at the final output boundary. This matters at team-season scale: Boston's 2023-24 eFG% is 0.57821796, which the league publishes as .578, but a float-based intermediate rounding can move the third decimal.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Basketball-Reference.com Glossary, entry 'eFG%': "Effective Field Goal Percentage; the formula is (FG + 0.5 * 3P) / FGA. This statistic adjusts for the fact that a 3-point field goal is worth one more point than a 2-point field goal." Includes the Player A / Player B illustration reproduced above.
2. [2]NBA.com official Stats Glossary, entry 'Effective Field Goal Percentage': "Measures field goal percentage adjusting for made 3-point field goals being 1.5 times more valuable than made 2-point field goals. Formula ((FGM + (0.5 * 3PM)) / FGA". The league's own definition.
3. [3]Basketball-Reference.com, 'Four Factors' — Dean Oliver's Four Factors of Basketball Success, with shooting weighted at approximately 40% and measured by eFG% on both offence and defence, worked through with 2004-05 Phoenix Suns totals.
4. [4]NBA Official Rulebook, Rule 5 (Scoring and Timing) — a successful field goal attempted from beyond the three-point field goal line counts three points; all other successful field goals count two points. This is the source of the 3/2 = 1.5 ratio behind the 0.5 coefficient.
5. [5]Basketball-Reference.com, 2023-24 NBA Season Summary — team and opponent totals plus the published Advanced table. Source of the Boston Celtics line used in the worked example (FG 3601, FGA 7396, 3P 1351, published eFG% .578) and of the 2023-24 league-average eFG% of .547.
6. [6]Sports Reference LLC, Basketball Glossary knowledge-base article — the publisher's own maintained copy of the stat definitions, giving eFG% as (FG + 0.5 * 3P) / FGA.
7. [7]Oliver, D. (2004). Basketball on Paper: Rules and Tools for Performance Analysis. Potomac Books. The origin of the Four Factors framework, of the possession-based efficiency ratings, and of the argument that shooting efficiency measured by eFG% dominates the other factors.