What Is a Basketball Efficiency Rating Calculator?
Efficiency Rating (EFF) is the NBA's basic all-in-one box score statistic. It adds together every positive stat a player recorded — points, rebounds, assists, steals and blocks — and subtracts every stat that represents a wasted possession — missed field goals, missed free throws and turnovers. The result is a single number summarizing a player's overall statistical output in a game.
It's the same formula the NBA has published box score "EFF" totals with for years, and it remains a quick, transparent way to compare box score lines without needing advanced pace or possession data.
How to Read Your Results
Efficiency Rating (EFF)
The final score: positive contributions minus negative contributions. Higher is better. A typical NBA starter might post an EFF in the high teens to low 20s on a good night; All-Star-caliber performances often reach the mid-20s to 30s or higher.
Positive Contributions
The sum of points, rebounds, assists, steals and blocks — everything the formula counts in the player's favor.
Negative Contributions
The sum of missed field goals, missed free throws and turnovers — everything the formula counts against the player.
Total Possessions Used
The same negative-contribution total, shown separately as a quick read on how many possessions ended without a scoring outcome.
Real-World Example
A player scores 20 points, grabs 8 rebounds, dishes 5 assists, records 2 steals and 1 block, while missing 8 field goals, 2 free throws, and committing 3 turnovers.
| Component | Value |
|---|---|
| Positive contributions (20+8+5+2+1) | 36 |
| Negative contributions (8+2+3) | 13 |
| Efficiency Rating (EFF) | 23 |
An EFF of 23 in a single game is a strong, well-rounded stat line — the kind of performance that would typically rank among a team's top contributors that night.
Tips for Interpreting EFF
- EFF favors high-usage players who take a lot of shots and touch the ball often — it doesn't measure efficiency in the shooting-percentage sense.
- It ignores defense beyond steals and blocks — good on-ball defenders who don't rack up steals can be undervalued.
- Compare players over similar minutes played rather than raw single-game totals for a fairer picture.
- For a deeper, pace-adjusted view, look at advanced metrics like PER or Win Shares alongside EFF, not instead of it.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team