Possessions ≈ Opp FGA - Opp ORB + Opp TOV + (0.44 × Opp FTA)
This formula normalizes defensive performance to a "per 100 possessions" basis. This allows you to compare the defense of a slow-paced team (few possessions) with a fast-paced team (many possessions) fairly.
"Defense wins championships" is a cliché, but Defensive Efficiency is the metric that proves it. By measuring stops per possession rather than just raw points, coaches can evaluate their system's true integrity.
Defensive Efficiency, or Defensive Rating (DRtg), estimates the number of points a team allows per 100 possessions. Unlike raw "Opponent Points Per Game," which can be skew, this metric accounts for pace.
It asks the question: "When the opponent has the ball 100 times, how many points do they score?"
Individual vs. Team DRtg
While this calculator primarily computes absolute efficiency (best used for teams), analysts also calculate "Individual Defensive Rating." Individual DRtg estimates how many points the player's matchup scores while they are on the court. It is notoriously difficult to calculate accurately without play-by-play data, whereas Team Defensive Rating is extremely reliable and easy to compute with box score data.
Why Use DRtg Over "Points Allowed"?
Consider two defensive scenarios:
Team A (Slow Pace): Allows 90 points per game, but opponents only have 80 possessions.
Team B (Fast Pace): Allows 110 points per game, but opponents have 115 possessions.
Team A DRtg: (90/80)*100 = 112.5 (Terrible Defense)
Team B DRtg: (110/115)*100 = 95.6 (Elite Defense)
Even though Team A allows 20 fewer points per game, their defense is actually worse because opponents score more efficiently every time they touch the ball. Team B just plays at a lightning pace, inflating the score.
The Formula Explained
The core of the calculation is estimating Possessions. We use the opponent's offensive stats:
DRtg = 100 × (Opponent Points / Possessions)
Where Possessions ≈ Opp FGA - Opp ORB + Opp TOV + (0.44 × Opp FTA)
Every possession ends in a shot (FGA), a turnover (TOV), or free throws (FTA). Subtracting offensive rebounds prevents double-counting the same possession.
Benchmarks: What Makes a Good Defense?
In the modern high-scoring era, benchmarks have shifted. Here is a general guide:
Elite (Below 108)
A "lockdown" defense. Teams in this range usually have a Defensive Player of the Year candidate and disciplined rotations.
Detailed (108 - 112)
Solid playoff defense. Good enough to win providing the offense carries its weight.
Average (113 - 116)
League average performance. You likely need a top-10 offense to be a serious contender.
Poor (Above 116)
Defensive sieve. Opponents are scoring comfortably. Common in rebuilding teams or those that sacrifice defense for offense.
The Four Factors of Defense
To improve your DRtg, focus on Dean Oliver's "Four Factors" applied defensively:
1. Opponent eFG% (Stop the Shot)
Force tough, contested shots. Eliminate open corner 3s and layups.
2. Defensive Rebounding (End the Possession)
Forcing a miss means nothing if you don't get the rebound. Limiting opponent offensive rebounds (ORB%) is critical to ending possessions.
3. Forced Turnovers (Create Chaos)
Turnovers are the best defensive outcome. They yield 0 points resulting in a "stop," and often lead to easy transition buckets for you.
4. Free Throw Prevention (Discipline)
Don't bail out bad offense with a foul. Free throws are the most efficient shot in the game. Defend without fouling.
Strategies to Improve DRtg
Communication: Most defensive breakdowns occur due to missed switches or confusion.
Protect the Paint: Shots at the rim are high percentage. A rim protector lowers opponent eFG%.
Transition Defense: Sprint back. Don't give up easy points before your defense is set.
Know Personnel: Force shooters to drive, force drivers to shoot.
Conclusion
Defensive Efficiency is the honest truth about your team's ability to stop the ball. It eliminates pace biases and exposes weaknesses in rebounding or fouling. Use this calculator to track your team's progress game-by-game and compare yourself to elite benchmarks.
Frequently Asked Questions
Common questions about Defensive Rating and efficiency
Is a higher or lower Defensive Rating better?
Lower is better. Since it measures "Points Allowed," you want this number to be as small as possible. This is the opposite of Offensive Rating, where higher is better.
How does this differ from "Adjusted Defensive Rating"?
This calculator computes raw Defensive Rating based on box score stats. "Adjusted" ratings (often found on sites like KenPom or Basketball Reference) further adjust this number based on the quality of the opponent. A good defensive game against an elite offense is worth more than a good game against a bad offense.
Can I calculate individual player DRtg here?
Not directly. While you can input the stats opponents accumulated while a player was on the court, standard individual DRtg formulas are much more complex and involve play-by-play data to assign credit for stops. This tool is best for Team Defensive Efficiency or Lineup Efficiency.
Why are offensive rebounds subtracted from possessions?
When an opponent grabs an offensive rebound, their possession continues. It's not a new possession. Subtracting the ORB ensures we don't count the same possession twice, which allows us to accurately measure points per unique possession.
What is "Net Rating"?
Net Rating is simply Offensive Rating minus Defensive Rating. It represents the point differential per 100 possessions. A positive Net Rating means you are outscoring opponents; a negative one means you are being outscored.
How do turnovers affect Defensive Rating?
Forced turnovers increase the possession count (denominator) while adding 0 points (numerator). This mathematically lowers your DRtg, which is good. They are essentially "empty possessions" for the opponent.
Does pace affect Defensive Rating?
No, and that is the point. DRtg is "pace-neutral." Whether you play 80 possessions or 120 possessions, the rating normalizes to 100. This is why it is the superior metric for comparing defenses across different eras or styles of play.
What is a "Stop"?
A "Stop" is a possession where the opponent scores 0 points. Estimates suggest roughly 50% of possessions end in scores. Elite defenses aim to increase their "Stop Rate" by stringing together consecutive stops (often called "Turkeys" or "Kills" in coaching lingo).
Usage of this Calculator
Who Should Use This?
CoachesEvaluate defensive performance beyond the scoreboard. Identify if a loss was due to bad defense or just bad offense.
AnalystsCompare historical teams. Is the 2004 Pistons defense actually better than the 2017 Warriors defense?
PlayersUnderstand the value of a stop. Learn why defensive rebounding is just as important as blocking shots.
Fantasy ManagersTarget players on teams with high pace but bad defensive ratings (high points allowed) for opponent matchups.
Summary
The Basketball Defensive Efficiency Calculator (DRtg) provides the most accurate assessment of a team's ability to prevent scoring.
By focusing on points allowed per 100 possessions, it empowers coaches to identify systemic issues and validate defensive improvements regardless of game speed.
Embed This Calculator
Add this calculator to your website or blog using the embed code below:
<div style="max-width: 600px; margin: 0 auto;">
<iframe
src="https://mycalculating.com/basketball-defensive-efficiency-calculator?embed=true"
width="100%"
height="600"
style="border:1px solid #ccc; border-radius:8px;"
loading="lazy"
title="${formatCalculatorTitle(calculatorSlug)} Calculator by MyCalculating.com"
></iframe>
<p style="text-align:center; font-size:12px; margin-top:4px;">
<a href="https://mycalculating.com/basketball-defensive-efficiency-calculator" target="_blank" rel="noopener">
Use full version on <strong>MyCalculating.com</strong>
</a>
</p>
</div>
Calculate defensive efficiency rating to measure points allowed per 100 possessions.
How to use Basketball Defensive Efficiency Calculator
Step-by-step guide to using the Basketball Defensive Efficiency Calculator:
Enter your values. Input the required values in the calculator form
Calculate. The calculator will automatically compute and display your results
Review results. Review the calculated results and any additional information provided
Frequently asked questions
How do I use the Basketball Defensive Efficiency Calculator?
Simply enter your values in the input fields and the calculator will automatically compute the results. The Basketball Defensive Efficiency Calculator is designed to be user-friendly and provide instant calculations.
Is the Basketball Defensive Efficiency Calculator free to use?
Yes, the Basketball Defensive Efficiency Calculator is completely free to use. No registration or payment is required.
Can I use this calculator on mobile devices?
Yes, the Basketball Defensive Efficiency Calculator is fully responsive and works perfectly on mobile phones, tablets, and desktop computers.
Are the results from Basketball Defensive Efficiency Calculator accurate?
Yes, our calculators use standard formulas and are regularly tested for accuracy. However, results should be used for informational purposes and not as a substitute for professional advice.