Basketball Stats Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: August 19, 2026Boiling a Box Score Down to One Number
A box score full of points, rebounds, assists, steals, blocks, and shooting attempts tells you a lot, but not at a glance which of two very different stat lines was actually more valuable. The Efficiency (EFF) formula, the simplified version popularized by NBA.com, exists to compress a full box score into a single comparable figure by rewarding production and penalizing missed shots and turnovers.
The Formula
This calculator uses the standard simplified Efficiency formula:
Every made shot and defensive/playmaking stat adds to the total, while missed field goals, missed free throws, and turnovers subtract from it. Because it treats every counting stat as worth exactly one point, EFF is a simplified measure — it doesn't weight three-pointers, assists, or blocks differently — but it remains a widely used quick-reference stat precisely because of that simplicity.
Where This Calculation Matters
- Post-game player comparison — ranking every player in a box score by a single EFF number gives an immediate, if rough, read on who produced the most.
- Season tracking — averaging EFF per game across a season shows overall production trends more cleanly than any single counting stat.
- Recreational and fantasy leagues — leagues that don't track advanced metrics like PER often use EFF as an accessible stand-in.
- Shot-selection awareness — because missed shots subtract directly from EFF, the formula rewards efficient shooting, not just high volume.
How to Use This Calculator
- Enter Points, Rebounds, Assists, Steals, and Blocks.
- Enter Field Goals Attempted and Field Goals Made.
- Enter Free Throws Attempted and Free Throws Made.
- Enter Turnovers.
- Select Calculate to see the EFF score and the full arithmetic breakdown.
Related Calculations
For a shooting-specific efficiency figure that accounts for three-pointers and free throws together, see the Basketball True Shooting Percentage Calculator. For a comparable single-number rating in another sport, check the Football Passer Rating Calculator.
Principles of Advanced Basketball Analytics and Sabermetric Modeling
A basketball statistics calculator computes traditional box-score metrics and advanced efficiency statistics for individual basketball players and teams across the NBA, WNBA, NCAA, and FIBA. In modern sports analytics, advanced metrics evaluate true scoring efficiency, shooting economy, and total offensive/defensive contributions per 100 possessions.
True Shooting Percentage (TS%) and Effective Field Goal % (eFG%)
- Effective Field Goal Percentage (eFG%): Adjusts raw field goal percentage for the fact that a 3-point field goal is worth 50% more points than a 2-point field goal:
eFG% = [ ( FGM + 0.5 × 3PM ) / FGA ] × 100%
- True Shooting Percentage (TS% — The Ultimate Scoring Efficiency Metric): Measures total shooting efficiency by incorporating 2-point field goals, 3-pointers, and free throws into a single metric:
TS% = [ Total Points / ( 2 × [ FGA + 0.44 × FTA ] ) ] × 100%Where 0.44 accounts for free throw trips from and-ones, technical fouls, and 3-point shooting fouls. (NBA league average TS% ≈ 57.0% to 58.5%).
Dean Oliver's "Four Factors" of Basketball Success
| The Four Factors | Mathematical Formula | Importance Weighting |
|---|---|---|
| 1. Shooting Efficiency | Effective Field Goal % (eFG%) | 40% of Team Success |
| 2. Turnover Rate | TOV% = TOV / ( FGA + 0.44×FTA + TOV ) | 25% of Team Success |
| 3. Rebounding Dominance | ORB% = Offensive Rebounds / ( ORB + Opponent DRB ) | 20% of Team Success |
| 4. Free Throw Generation | Free Throw Rate (FTR) = FTA / FGA | 15% of Team Success |
Step-by-Step Worked Calculation Example
Example: Comparing Scoring Efficiency between Two NBA Scorers
Problem: Player A scores 28 points on 10/22 FG (2/6 3PT) and 6/6 FT. Player B scores 25 points on 8/14 FG (5/9 3PT) and 4/5 FT. Calculate: (1) Raw FG% for both; (2) eFG% for both; and (3) True Shooting Percentage (TS%) for both.
Step 1: Calculate Raw Field Goal Percentage (FG%):
Player A FG% = 10 / 22 = 45.45% | Player B FG% = 8 / 14 = 57.14%
Step 2: Calculate Effective Field Goal Percentage (eFG%):
Player A eFG% = [ 10 + 0.5(2) ] / 22 = 11 / 22 = 50.00%
Player B eFG% = [ 8 + 0.5(5) ] / 14 = 10.5 / 14 = 75.00%
Step 3: Calculate True Shooting Percentage (TS%):
Player A TS% = 28 / [ 2 × ( 22 + 0.44 × 6 ) ] = 28 / [ 2 × 24.64 ] = 28 / 49.28 = 56.82%
Player B TS% = 25 / [ 2 × ( 14 + 0.44 × 5 ) ] = 25 / [ 2 × 16.20 ] = 25 / 32.40 = 77.16%
Conclusion: While Player A scored 3 more raw points, Player B generated 25 points with extraordinary elite efficiency (77.2% TS% vs 56.8% TS%), consuming 17 fewer offensive possessions.
Usage Rate (USG%) and Offensive Rating (ORtg)
- Usage Rate (USG%): The percentage of team offensive plays used by a player while on court (shots, free throws, turnovers; league leaders sustain 30% to 35%+).
- Offensive Rating (ORtg): Estimated points generated per 100 team possessions (elite efficiency > 120.0).
John Hollinger's Player Efficiency Rating (PER)
Developed by John Hollinger, Player Efficiency Rating (PER) is an all-in-one per-minute rating that sums all positive player contributions (points, rebounds, assists, steals, blocks), subtracts negative actions (missed shots, turnovers, personal fouls), and normalizes for team pace:
Pace-Adjusted PER = uPER × ( lgPace / tmPace ) × ( 15.0 / lg_uPER )
The league average PER is mathematically standardized to exactly 15.00 every season. All-Star caliber players achieve PER > 20.0, while MVP candidates sustain PER > 25.0 to 30.0+.
Estimated Plus-Minus (EPM) and Regularized Adjusted Plus-Minus (RAPM)
Modern NBA front offices evaluate roster additions using ridge-regression RAPM and EPM models, isolating an individual player's net on-court point impact per 100 possessions while mathematically controlling for the quality of all nine other teammates and opponents on the floor.
Value Over Replacement Player (VORP) and Box Plus-Minus (BPM)
In modern NBA quantitative analytics, Box Plus-Minus (BPM) estimates a basketball player's net efficiency impact per 100 team possessions above a league-average baseline (0.0 BPM).
Translating BPM into full-season value yields Value Over Replacement Player (VORP):
A player with VORP > 5.0 represents an elite All-NBA superstar contributing more than 5 additional wins above a freely available minor-league replacement player.
Clutch Time Efficiency Metrics in the NBA
In professional basketball sabermetrics, the NBA defines Clutch Time as the final 5 minutes of the fourth quarter or overtime when the scoring margin is 5 points or fewer.
Evaluating clutch True Shooting Percentage (TS%), assist-to-turnover ratio, and defensive stop frequency identifies closing players whose performance elevates under high-stress endgame pressure.
Shot Quality and Expected Field Goal Percentage (xFG%)
Modern NBA tracking cameras calculate Expected Field Goal Percentage (xFG%) for every shot attempt based on defender closeout distance, shooter movement velocity, and court location, evaluating whether a player consistently generates high-quality open looks.
Defensive Rating and Individual Defensive Impact
Individual Defensive Rating (DRtg) estimates points allowed per 100 possessions while on floor, incorporating defensive stops, opponent field goal suppression, and defensive rebound percentage.