The Stat Used to Calculate a QB’s Passer Rating: A Deep Dive
An interactive tool and guide to understanding the official NFL passer rating formula.
QB Passer Rating Calculator
What is the NFL Passer Rating?
The NFL’s official passer rating is a metric used to measure the performance of quarterbacks, adopted by the league in 1973. It is often the primary stat used to calculate a QB’s passer rating for media like the NYT and other sports outlets. The formula combines four key passing statistics—completions, attempts, yards, touchdowns, and interceptions—into a single, standardized number. The rating scale ranges from 0 to a “perfect” 158.3. It’s crucial to distinguish this from ESPN’s proprietary Total Quarterback Rating (QBR), which uses a different, more complex formula as detailed in our analysis of QB rating vs QBR.
This statistic was designed to create a standard way to compare passers across different seasons. It exclusively measures passing efficiency and does not account for a quarterback’s rushing ability, leadership, or the context of game situations (like sacks or fumbles), which are important factors in overall player evaluation.
The Passer Rating Formula and Explanation
The passer rating calculation is a four-step process. Each step calculates a component based on a quarterback’s performance, and each component is capped between 0 and 2.375. This cap prevents exceptionally high or low stats in one area from disproportionately skewing the overall rating.
- Completion Component (a): `a = ((COMP / ATT) – 0.3) * 5`
- Yards Per Attempt Component (b): `b = ((YDS / ATT) – 3) * 0.25`
- Touchdown Component (c): `c = (TD / ATT) * 20`
- Interception Component (d): `d = 2.375 – ((INT / ATT) * 25)`
After calculating a, b, c, and d (and applying the 0 to 2.375 cap to each), the final rating is calculated with this formula:
Passer Rating = ((a + b + c + d) / 6) * 100
| Variable | Meaning | Unit | Typical Range (for a full game) |
|---|---|---|---|
| ATT | Pass Attempts | Unitless | 20 – 50 |
| COMP | Completions | Unitless | 15 – 40 |
| YDS | Passing Yards | Yards | 150 – 450 |
| TD | Touchdowns | Unitless | 0 – 5 |
| INT | Interceptions | Unitless | 0 – 4 |
Practical Examples
Example 1: A “Perfect” Game
Let’s see what it takes to get the maximum rating of 158.3. The formula requires high performance in all categories.
- Inputs: 25 Attempts, 22 Completions, 350 Yards, 4 Touchdowns, 0 Interceptions
- Calculations:
- Completion %: 88.0% -> Component a = 2.375 (capped from 2.9)
- Yards/Attempt: 14.0 -> Component b = 2.375 (capped from 2.75)
- Touchdown %: 16.0% -> Component c = 2.375 (capped from 3.2)
- Interception %: 0.0% -> Component d = 2.375
- Result: `((2.375 + 2.375 + 2.375 + 2.375) / 6) * 100 = 158.3`
Example 2: An Average Game
Here’s a more typical stat line for a solid, but not spectacular, performance.
- Inputs: 35 Attempts, 23 Completions, 250 Yards, 2 Touchdowns, 1 Interception
- Calculations:
- Completion %: 65.7% -> Component a = 1.786
- Yards/Attempt: 7.14 -> Component b = 1.036
- Touchdown %: 5.7% -> Component c = 1.143
- Interception %: 2.9% -> Component d = 1.661
- Result: `((1.786 + 1.036 + 1.143 + 1.661) / 6) * 100 = 93.8`
How to Use This Passer Rating Calculator
Using this calculator is simple. Follow these steps to determine any quarterback’s passer rating for a game, season, or even a single drive.
- Enter Pass Attempts: Input the total number of passes the QB threw. This is the foundation for all the rate-based stats.
- Enter Completions: Input how many of those passes were caught by a receiver. The calculator will validate that this is not more than the attempts.
- Enter Passing Yards: Input the total yardage gained from the completed passes.
- Enter Touchdowns & Interceptions: Input the number of TD passes and interceptions thrown.
- View Real-Time Results: The calculator automatically updates the total passer rating and the four underlying component scores as you type. This allows you to see exactly how each stat impacts the final number. To fully grasp how to calculate QB rating, watch how the components change with each input.
Key Factors That Affect Passer Rating
While the formula is rigid, several on-field factors directly influence its inputs and, therefore, the resulting rating.
- Accuracy: Directly impacts completion percentage (Component a). Higher accuracy leads to a higher rating.
- Decision Making: A QB’s ability to avoid risky throws keeps interception numbers low, maximizing Component d.
- Arm Strength & Deep Ball Accuracy: Successful deep passes significantly boost Yards Per Attempt (Component b).
- Offensive Line Play: Good protection gives a QB more time to find open receivers downfield, positively impacting both yards and completion percentage.
- Receiver Skill: Elite receivers can turn short passes into long gains (boosting yards) and have lower drop rates (boosting completions). This is a key part of evaluating fantasy football weekly projections.
- Red Zone Efficiency: Converting drives into touchdowns instead of field goals increases the Touchdown Percentage (Component c).
Frequently Asked Questions
- 1. What is a “perfect” passer rating?
- A perfect passer rating is 158.3. It is achieved when a quarterback’s performance meets or exceeds specific high-performance thresholds in all four components of the formula (e.g., >=77.5% completion rate, >=12.5 yards per attempt, >=11.875% TD rate, and 0 interceptions).
- 2. What is the lowest possible passer rating?
- The lowest possible rating is 0.0. This occurs if a quarterback’s performance is below the minimum threshold for all four components (e.g., <30% completion rate, <3 yards per attempt, 0 TDs, and >9.5% interception rate).
- 3. Is passer rating the same as QBR?
- No. Passer rating is the official NFL stat since 1973, based on a fixed formula. Total Quarterback Rating (QBR) is a proprietary ESPN metric created in 2011 that includes context like rushing, sacks, fumbles, and game situation (e.g., “clutch” plays).
- 4. Why is the maximum rating 158.3?
- The number is a result of the formula’s structure. When each of the four components (a, b, c, d) reaches its maximum capped value of 2.375, the final calculation `((2.375 * 4) / 6) * 100` equals 158.3.
- 5. Can a good passer rating be misleading?
- Yes. A high rating can be inflated by “garbage time” stats when a game is already decided. It also doesn’t penalize a QB for taking sacks instead of throwing the ball away, a topic covered in discussions about quarterback power rankings.
- 6. Does the formula account for rushing yards or touchdowns?
- No. The official NFL passer rating only evaluates passing statistics. A quarterback’s rushing contributions are not factored in, which is a key difference compared to QBR.
- 7. How has the average passer rating changed over time?
- The league-average passer rating has steadily increased since its introduction due to more pass-friendly rules, offensive scheme evolution, and higher overall efficiency. The average rating in modern eras is significantly higher than it was in the 1970s or 1980s, an important factor when looking at all-time passing leaders.
- 8. What is a good passer rating in today’s NFL?
- While it fluctuates yearly, a rating over 95 is generally considered good, over 100 is excellent, and over 110 is elite. The league average typically hovers in the low 90s.