Effective Field Goal Percentage (eFG%) Calculator

Background.

Two players each take ten shots. Player A makes four, two of them three-pointers; Player B makes five, all twos. The box score says B shot 50% and A shot 40%, yet both scored exactly ten points from the floor on the same ten attempts. Basketball-Reference uses this pair to explain effective field goal percentage, and it captures the whole idea: plain field goal percentage counts a made three and a made lay-up as the same event, so it undersells anyone whose makes come from behind the arc.

The fix is small. eFG% credits each made three as one and a half makes, because three points is one and a half times two, and divides by attempts as usual: (FG + 0.5 × 3P) ÷ FGA. Player A becomes (4 + 1) ÷ 10 = 50%, level with Player B, which is the fair verdict. The NBA's own stats glossary and Basketball-Reference publish the formula in exactly this form, and it works unchanged for any league that scores threes at three points.

The correction matters more every season. The NBA introduced its three-point line in 1979-80, and teams have since moved shots away from long two-pointers and out to the arc. That shift tends to lower a team's field goal percentage while raising its scoring, a change that FG% reads as worse shooting and eFG% reads correctly as better. It is also why Dean Oliver chose eFG% to measure shooting, the heaviest of his Four Factors of winning basketball. Enter three numbers from any box score and you get eFG%, conventional FG% beside it, points from field goals, points per attempt, and the gap the three-pointers open between the two percentages.

What is effective field goal percentage calculator?

Effective field goal percentage is field goals made plus half the three-pointers made, divided by field goal attempts. Since every made three is already inside FG, adding 0.5 × 3P lifts each three to 1.5 makes while each two still counts once, exactly the ratio of their point values. The result is a rescaled points-per-shot figure: eFG% is precisely half of points per field goal attempt, so 50% means one point per shot and 57.82% means 1.1564. The rescaling makes unlike shooters comparable: someone who takes only threes and hits 34% of them has an eFG% of 51%, slightly better than a player who takes only twos and hits 50%, even though 34% looks poor on a stat sheet. It is a rate, not a volume measure, and says nothing about how many shots a player takes or how hard they were. It leaves out free throws entirely, which is the main difference from true shooting percentage, and it is applied in the same way to a player's night, a team's season, or the shots a defence allows its opponents.

How to use this calculator.

1. 01Enter field goals made: every made shot from the floor, twos and threes together, the first number in a shooting line such as 9-20. Free throws are not field goals.
2. 02Enter field goal attempts, the second number in the line. Under standard scoring a missed shot on which the shooter was fouled is not charged as an attempt, while a made shot with a foul, an and-one, counts as an attempt and a make.
3. 03Enter three-pointers made, which are already included in field goals made and so can never exceed them. For an NBA season before 1979-80, enter 0. A 9-20 line with three made threes, for example, gives (9 + 1.5) ÷ 20 = 52.5%, against a plain 45%.
4. 04Compare eFG% with the conventional FG% shown beside it; the gap between them is the value of the three-pointers, and it grows with the share of attempts that fall from deep.
5. 05Judge the result against the average for the same league and season, and run your opponents' totals too, since the difference between the two is the shooting factor in Dean Oliver's Four Factors.

The formula.

eFG% = (FG + 0.5 × 3P) ÷ FGA, shown as a percentage. The 0.5 comes straight from points. Two-point makes are FG − 3P, so points from the floor are 2 × (FG − 3P) + 3 × 3P = 2 × FG + 3P. Divide by attempts and you have points per field goal attempt, (2 × FG + 3P) ÷ FGA; take the 2 outside the bracket and what remains is (FG + 0.5 × 3P) ÷ FGA. So eFG% is points per shot divided by two, put on the familiar percentage scale where a shooter who only takes twos and makes half of them scores 50%. Nothing about the coefficient is estimated from data. It is the extra half-basket a three is worth under the scoring rule, NBA Rule 5, which gives three points for a field goal from beyond the arc and two for every other one.

The same arithmetic gives the other outputs. Conventional FG% is FG ÷ FGA. Points from field goals are 2 × FG + 3P. Points per attempt are that total over FGA, always exactly twice eFG%. The gap between eFG% and FG% is 0.5 × 3P ÷ FGA, half the share of attempts that became made threes, so it is zero for a player who never makes a three and grows as more makes come from deep.

The formula also sets the break-even between shots. A three at percentage p₃ is worth 3 × p₃ points per attempt and a two at p₂ is worth 2 × p₂, so the three is the better shot whenever p₃ exceeds two-thirds of p₂. Against a 50% two that threshold is 33.3%; against a 45% jumper, 30%.

The upper limit is 150%, reached by a player who makes every attempt and every attempt is a three. Free throws, turnovers, offensive rebounds, assists and the difficulty of each shot are outside the formula, which is why a team can lose the eFG% comparison and still win the game by getting to the line more often, giving the ball away less or collecting more second chances.

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.