How is Quarterback Rating Calculated?

An interactive calculator and in-depth guide to the official NFL Passer Rating formula.

NFL Passer Rating Calculator

What is Quarterback Rating?

Quarterback Rating, officially known as Passer Rating in the NFL, is a statistical tool used to measure the performance of a quarterback. Adopted by the NFL in 1973, it combines four key passing metrics—completion percentage, yards per attempt, touchdown percentage, and interception percentage—into a single, standardized number. The scale ranges from a minimum of 0 to a maximum, or “perfect,” rating of 158.3.

This rating system was designed to provide a more holistic view of a passer’s efficiency than any single stat could offer. It is crucial to distinguish the official Passer Rating from other metrics like ESPN’s Total Quarterback Rating (QBR), which uses a different formula and includes factors like rushing and game context. The focus of this calculator is strictly on the official NFL Passer Rating formula.

The Quarterback Rating Formula and Explanation

The calculation of NFL passer rating involves a four-step process where each component is individually calculated and then capped. The sum of these capped values is then used to produce the final rating.

1. Calculate Component A (Completion Percentage): `a = ((COMP / ATT) – 0.3) * 5`
2. Calculate Component B (Yards Per Attempt): `b = ((YDS / ATT) – 3) * 0.25`
3. Calculate Component C (Touchdown Percentage): `c = (TD / ATT) * 20`
4. Calculate Component D (Interception Percentage): `d = 2.375 – ((INT / ATT) * 25)`

A critical rule is that each component (a, b, c, d) cannot be greater than 2.375 or less than 0. If a calculation yields a result outside this range, it is capped at the nearest limit. Finally, these four components are summed up to find the passer rating:

Passer Rating = ((a + b + c + d) / 6) * 100

Variable Explanations for the Passer Rating Formula

Variable	Meaning	Unit	Typical Range (per game)
COMP	Completions	Count (unitless)	15 – 35
ATT	Attempts	Count (unitless)	25 – 50
YDS	Passing Yards	Yards	150 – 400
TD	Touchdowns	Count (unitless)	0 – 4
INT	Interceptions	Count (unitless)	0 – 3

For more on the history of this metric, see this article on the history of NFL stats.

Practical Examples of Passer Rating Calculation

Example 1: A Great Performance

Let’s calculate the rating for a stellar game: 28 completions on 35 attempts for 350 yards, 4 touchdowns, and 0 interceptions.

• Inputs: COMP=28, ATT=35, YDS=350, TD=4, INT=0
• a (Completions): `((28/35) – 0.3) * 5 = (0.8 – 0.3) * 5 = 2.5`. Capped at 2.375.
• b (Yards): `((350/35) – 3) * 0.25 = (10 – 3) * 0.25 = 1.75`.
• c (Touchdowns): `(4/35) * 20 = 0.114 * 20 = 2.28`.
• d (Interceptions): `2.375 – ((0/35) * 25) = 2.375`.
• Final Rating: `((2.375 + 1.75 + 2.28 + 2.375) / 6) * 100 = (8.78 / 6) * 100 = 146.3`

Example 2: A Tough Outing

Now consider a more difficult game: 15 completions on 32 attempts for 160 yards, 1 touchdown, and 3 interceptions. Understanding the ESPN’s Total QBR might also provide context on difficult games.

• Inputs: COMP=15, ATT=32, YDS=160, TD=1, INT=3
• a (Completions): `((15/32) – 0.3) * 5 = (0.46875 – 0.3) * 5 = 0.844`.
• b (Yards): `((160/32) – 3) * 0.25 = (5 – 3) * 0.25 = 0.5`.
• c (Touchdowns): `(1/32) * 20 = 0.03125 * 20 = 0.625`.
• d (Interceptions): `2.375 – ((3/32) * 25) = 2.375 – (0.09375 * 25) = 2.375 – 2.34375 = 0.031`.
• Final Rating: `((0.844 + 0.5 + 0.625 + 0.031) / 6) * 100 = (2.0 / 6) * 100 = 33.3`

How to Use This Quarterback Rating Calculator

Using this calculator is straightforward and provides instant results.

1. Enter the Stats: Input the five required values (Completions, Attempts, Yards, Touchdowns, and Interceptions) into their respective fields. The calculator updates in real-time as you type.
2. Review the Rating: The primary result area displays the final calculated Passer Rating, rounded to one decimal place.
3. Analyze the Components: Below the main result, you can see the four individual component scores (a, b, c, d) after capping. This helps you understand which aspects of the performance most influenced the final score. The bar chart also visualizes the strength of each component relative to the maximum of 2.375.
4. Reset or Copy: Use the “Reset” button to clear all fields and start over. Use the “Copy Results” button to save a summary of the inputs and results to your clipboard.

For more on passing efficiency, a related metric is the Adjusted Net Yards Per Attempt (ANY/A), which also accounts for sacks.

Key Factors That Affect Quarterback Rating

Several key on-field factors directly influence a quarterback’s passer rating. Understanding these can provide deeper insight into how quarterback rating is calculated.

• Completion Percentage: This is the most straightforward factor. Higher completion rates directly boost component ‘a’. It rewards accuracy and safe throws.
• Yards Per Attempt (Y/A): This measures explosiveness and efficiency. A high Y/A significantly increases component ‘b’. It’s not just about completing passes, but gaining significant yardage with each throw.
• Touchdown Rate: Scoring is heavily weighted. A high percentage of touchdowns per attempt drives up component ‘c’, rewarding quarterbacks who are effective in the red zone and can deliver scoring plays.
• Interception Avoidance: Ball security is critical. A low interception rate is essential for a high rating, as each interception heavily penalizes component ‘d’. This is often a key differentiator between good and great quarterbacks.
• Aggressiveness vs. Caution: There is an inherent trade-off. Overly cautious play (short passes) might boost completion percentage but lower yards per attempt. Aggressive downfield throws can boost Y/A but risk incompletions and interceptions.
• Supporting Cast and Scheme: While an individual stat, passer rating is influenced by offensive line protection, receiver skill, and the offensive scheme’s design. This is why some consider it a measure of the entire passing offense’s efficiency. Discover how this impacts the careers of the greatest quarterbacks.

Frequently Asked Questions (FAQ)

1. What is a perfect passer rating?

A perfect passer rating is 158.3. To achieve this, a quarterback must meet or exceed minimum thresholds in all four components simultaneously: at least a 77.5% completion rate, at least 12.5 yards per attempt, a touchdown on at least 11.875% of attempts, and zero interceptions.

2. What is a “good” quarterback rating?

While subjective, a rating over 100.0 for a season is generally considered excellent. A rating in the 90s is very good, and a rating in the mid-to-high 80s is considered league average. Context matters, as league-average passer ratings have steadily increased over the decades.

3. Can a passer rating be negative?

No. The formula includes a rule that if any of the four base components (a, b, c, d) calculates to a negative number, it is set to zero for the final calculation. Therefore, the lowest possible passer rating is 0.

4. How is this different from ESPN’s QBR?

Passer Rating is a formula based only on raw passing stats. Total Quarterback Rating (QBR) is a more complex metric created by ESPN that attempts to measure a QB’s total contribution to winning. It includes rushing, sacks, penalties, and weights plays by their “Expected Points Added” (EPA) and situational context.

5. Who invented the passer rating formula?

A committee led by Don Smith, an executive at the Pro Football Hall of Fame, developed the system for the NFL in the early 1970s. It was officially implemented in 1973 to provide a standard method for ranking passers.

6. Does the formula account for sacks?

No, the official NFL passer rating formula does not include sacks or yards lost from sacks. This is a common criticism of the metric, as sacks are an important part of quarterback play. Other metrics, like Adjusted Net Yards per Attempt, do account for sacks.

7. Why is there a cap on each component?

The caps (from 0 to 2.375) were put in place to prevent a single outlier performance in one category from skewing the overall rating too heavily. It ensures a level of balance across the four core aspects of passing efficiency. For more on this, dive into advanced football analytics.

8. Is this the same formula used in college football?

No. NCAA college football uses a different “passing efficiency” formula that is not capped and results in a different scale of numbers. The NFL formula is unique to professional football.