Example data
| Scenario | Team ON | Opp ON | Min ON | Poss ON | Plus-Minus | Net Rating |
|---|---|---|---|---|---|---|
| Starter A (on-court) | 68 | 60 | 24 | 55 | +8 | +14.55 |
| Bench B (on-court) | 40 | 52 | 18 | 42 | -12 | -28.57 |
Formula used
On/Off plus-minus
- Plus-Minus (ON) = Team Points (ON) − Opponent Points (ON)
- Net Rating (ON) = (Plus-Minus (ON) ÷ Possessions (ON)) × 100
- Plus-Minus per 48 = (Plus-Minus (ON) ÷ Minutes (ON)) × 48
- On-Off Swing = Net Rating (ON) − Net Rating (OFF) (when OFF values are supplied)
Box-score estimate (transparent model)
- Estimated possessions ≈ 0.96 × (FGA + 0.44×FTA − ORB + TOV)
- Offensive box +/- (per 100) = 100 × (PTS + 0.5×3PM + 0.7×AST + 0.5×ORB − 0.9×FGA − 0.4×FTA − 1.0×TOV) ÷ Possessions
- Defensive box +/- (per 100) = 100 × (0.7×DRB + 1.5×STL + 1.2×BLK − 0.5×PF) ÷ Possessions
- Total box +/- = Offensive + Defensive
- Impact per 48 = Total box +/- × (Team Pace per 48 ÷ 100)
How to use this calculator
- Select On/Off plus-minus for lineup impact from scoring margin.
- Enter ON-court points and optionally minutes and possessions.
- Optionally add OFF-court values to see the on-off swing.
- Select Box-score estimate to estimate impact from box stats.
- Press Calculate to show results above the form.
- Use Download CSV or Download PDF to save outputs.
Why plus-minus matters
Plus-minus tracks the scoreboard while a player is on the floor, capturing scoring runs that traditional totals can miss, especially in playoffs. A +8 margin can reflect spacing, stops, or matchups. Coaches often pair it with film to confirm whether advantages came from shot quality, transition defense, or rebounding control. Because it is a margin statistic, it rewards impact that helps teammates score and prevents opponents from scoring.
Using possessions for context
Raw margins depend on pace, so possessions help normalize results. Net rating is calculated as (plus-minus ÷ possessions) × 100, making comparisons fair when one stint had 55 possessions and another had 42. If you track minutes, the calculator also reports per-48 values, which approximate what the margin would look like across a full game. For clean inputs, log possessions from play-by-play, or use your team’s internal tracking feed.
Reading on-off swings
On-off swing compares performance with the player on the floor versus off the floor. A positive swing suggests the team’s net rating improves during that player’s minutes, but it is sensitive to substitution patterns and opponent units. To reduce noise, evaluate longer samples such as multiple games, and separate by lineup combinations or roles. Consider adding context labels like “first quarter starters” or “small-ball unit” to keep exports organized.
Box-score estimate use cases
The box-score mode provides a transparent estimate built from points, shots, assists, rebounds, steals, blocks, turnovers, and fouls. It starts with an estimated possessions formula and converts contributions to per-100 and per-48 impact. This is helpful when full on-court tracking is unavailable, or when you want quick comparisons across players in the same competition. Treat it as directional: roles, defensive assignments, and screen setting are not fully captured by box events.
Reporting and workflow tips
Use the results panel to capture key KPIs: on-court margin, net rating, pace, and on-off swing. Export CSV for staff dashboards, and PDF for sharing after games. When comparing players, keep mode consistent and note minutes and possessions to avoid misleading conclusions. For best practice, combine this report with opponent strength, lineup spacing metrics, and video tags, then revisit trends weekly to guide rotation decisions.
FAQs
1) What is box plus minus?
It is the score margin while a player is on the court: team points minus opponent points during that stint. Positive values mean the team outscored opponents with the player on.
2) Why is net rating showing a dash?
Net rating needs possessions. If possessions are blank or zero, the calculator cannot compute per-100 values, so it shows a dash. Enter possessions for the stint to unlock net rating and pace.
3) How should I get possessions?
Use play-by-play or your tracking provider for the cleanest count. If you must estimate, use team possessions for the same minutes window. Keep the method consistent across players for fair comparisons.
4) What does on-off swing tell me?
On-off swing compares the team’s net rating with the player on the floor versus off. A positive swing suggests the team performs better during that player’s minutes, but it can reflect matchup and rotation context.
5) Can I compare results across teams or leagues?
You can, but adjust for pace, role, and competition level. Use net rating per 100 possessions instead of raw margin, and compare similar positions and minutes. Larger samples reduce random swing from a single game.
6) Is the box-score estimate an official model?
No. It is a transparent, input-driven estimate meant for quick checks when lineup data is missing. Use it alongside video, opponent strength, and role notes rather than as a standalone ranking.