How The 48 Index works

What the index measures

The 48 Index combines a player’s recorded box-score contributions into Offensive and Defensive indexes. Their sum is the Overall Index. Every game is scaled to the same 48-minute basis, then game-level scores are averaged across the selected sample.

Higher values mean more contributions under these weights. Scores can be negative and have no fixed upper limit. The index is not a 0–100 rating, a percentile, a wins estimate or a possession-based efficiency metric.

The formulas

Start with the recorded statistics from one game. Calculate the two raw contributions below, then multiply each by 48 ÷ minutes played.

PTS = points; FGM/FGA = field goals made/attempted; FTM/FTA = free throws made/attempted; AST = assists; OREB/DREB = offensive/defensive rebounds; TO = turnovers; PF = personal fouls; STL = steals; BLK = blocks; MIN = minutes played.

Every field-goal attempt carries −0.7. A make adds +0.4 back, alongside the points scored. An isolated missed field goal therefore costs 0.7; a missed free throw costs 0.4; a turnover costs 1.0. A missed shot is not treated as an automatic loss of possession. Three-pointers receive their value through points scored, with no separate three-point bonus.

Suppose a player records the following line in 32 minutes. The example uses the same scoring function as the player rankings.

The three personal fouls consist of one offensive, one defensive and one unclassified foul.

The raw Offensive contribution is 16.80; the raw Defensive contribution is 3.70. The scale factor is 48 ÷ 32 = 1.5.

Compared with Game Score

New to these terms? Read plus-minus versus a box-score index, or browse basketball stats explained.

The combined raw contribution uses the same box-score weights as Game Score, as defined by Basketball-Reference . Because every personal foul is counted once, Overall Index = Game Score × 48 ÷ minutes played for the same input statistics.

In the worked example, Game Score is 20.50. The Overall Index is 30.75 after the 48-minute adjustment. The split and averaging rules are our presentation of these contributions, not a new set of underlying Game Score weights.

Which games count

The default: latest 20 recorded games

Each player’s default index is the arithmetic mean of their latest 20 recorded, positive-minute appearances across all seasons and competitions. The twenty games belong to that player; they are not the league’s latest twenty fixtures or a fixed calendar period. A traded player keeps one identity across teams. A retired player can still appear because the archive is included.

Every included game counts equally. For example, Per48 scores of 48 and 16 average to 32, even if one game involved 10 minutes and the other 30. We do not combine the raw contributions and divide by total minutes. Fewer recorded appearances use the available sample where eligibility permits.

Eligibility is separate from the score sample

The default leaderboard requires an average above 10 minutes in the selected sample and at least 20 qualifying appearances in the scoring scope. Games-played eligibility is checked before limiting the scoring sample to the latest twenty. If the available data is sparse, the game minimum adapts to the available maximum; the average-minutes threshold relaxes when no players have more than 10 MPG.

An average above 10 MPG does not mean every included appearance lasted more than 10 minutes. By default, all positive-minute appearances count. The separate minimum-minutes-per-game setting can exclude short appearances before selecting the latest qualifying games. A zero-minute appearance receives no index.

Other selections

• Recent games: choose a game window across the full archive; season and competition do not restrict that sample.
• Season & competition: average all qualifying appearances in the chosen scope. Regular season, preseason, playoffs, play-in and NBA Cup finals are stored separately. “All competitions” includes them; All-Star exhibitions are excluded.
• Latest Game: a player’s latest recorded appearance within the past 15 calendar days, with more than 10 minutes. A short latest outing is not replaced by an older game.
• Draft Class: a draft-year cohort, not official NBA rookie eligibility. The preset uses up to 20 appearances in the cohort season and chosen competition.
• All Time: the average across the available archive, not lifetime points, a career-total score or a complete history of the NBA.

Source minute precision is preserved. A rounded minute value stays rounded; a source with seconds retains those seconds. Overtime games are still scaled to 48 minutes using the player’s recorded playing time.

Stat Leaders shows conventional per-game box-score averages and shooting percentages from total makes divided by total attempts. Those values are not Per48 indexes. Percentage categories require at least 5 field-goal attempts, 2 three-point attempts or 2 free-throw attempts per game respectively; three-point categories require complete three-point data throughout the sample.

How personal fouls are handled

Every box-score personal foul receives a −0.4 raw penalty. Offensive fouls affect Offense; defensive fouls affect Defense. When a reliable split is unavailable, an unclassified personal foul counts as defensive for this index, and the source uncertainty is retained and disclosed. No appearance is removed simply because its foul split is incomplete.

For some loose-ball, flagrant and double-personal fouls, clear possession context can determine the side. These are contextual assignments, not official NBA foul subtypes. Alternate records must agree on the game, player and total personal fouls before being used.

There is no additional technical-foul term. We use personal fouls recorded in the player’s box score; technical-foul events do not trigger a separate penalty. Moving a personal foul between the offensive and defensive buckets changes the split but leaves Overall unchanged.

How Watch Score works

Watch Score is a separate, experimental 0–100 rating for games worth catching up on. It combines four signals:

This rating is a transparent heuristic, not a validated prediction that everyone will enjoy a game.

Sources and limitations

• SportsDataverse / ESPNPrimary NBA scoreboard and player box-score feed.
• NBA.com statisticsOfficial tables used to verify and fill missing records.
• Historical NBA statistics archiveAdditional historical box scores, matched to game and player identity.
• NBA play-by-play archiveHistorical foul-side evidence, checked against total personal fouls.
• Basketball-Reference glossaryThe published Game Score definition used for the formula comparison.

Completed games are refreshed through the existing hourly update process. An hourly target is not a guarantee of instant source availability. Failed updates retain previously saved results. Missing history and unclassified fouls are disclosed; the archive should not be read as complete NBA coverage.

Short appearances can produce extreme Per48 rates. Minutes and games filters help with sample selection, but do not make those estimates certain. The index also does not adjust for pace, position, era or teammate effects. Treat it as one lens alongside actual minutes, box scores, game context and watching the player.

The idea grew out of morning catch-ups in Istanbul: following Alperen Şengün and other favorites after the overnight NBA games. Selim Yörük created The 48 Index as an independent fan project.

Common questions