NFL passer rating calculator
The NFL's official passer rating from the five numbers a box score gives you, with each of its four parts shown and the cap on every one made visible — because the formula's whole character is in those caps. Nothing you type here leaves your browser; it is worked out on your own device, so there is nothing to send and nothing to log.
The formula, and why it is four separate parts
Passer rating does not weigh one number against the rest in a single sum. It scores four things on their own, caps each one, and averages them. Each part is a rate — per attempt — so a quarterback who throws twice cannot post the same rating as one who threw forty times to the same effect.
| a | (completions / attempts − 0.3) × 5 |
|---|---|
| b | (yards / attempts − 3) × 0.25 |
| c | (touchdowns / attempts) × 20 |
| d | 2.375 − (interceptions / attempts) × 25 |
Each of a, b, c and d is then held between 0 and 2.375 — anything lower becomes 0, anything higher becomes 2.375 — and the rating is their average, scaled to look like a familiar number:
| Rating | ((a + b + c + d) / 6) × 100 |
|---|
Why it stops at 158.3
If all four parts hit their 2.375 ceiling, the sum is 4 × 2.375 = 9.5. Divide by 6 and multiply by 100 and you get 158.33, the famous “perfect” passer rating. It is not a round number because the formula was never built to top out at one; the ceiling is wherever the caps happen to land.
A perfect rating is harder than it sounds and does not need a perfect game. Each part caps out at a specific rate:
| Completions | 77.5% of attempts or better |
|---|---|
| Yards | 12.5 yards per attempt or better |
| Touchdowns | a touchdown on 11.875% of attempts or better |
| Interceptions | none |
Clear all four and the rating is 158.3 whether you threw ten passes or fifty. Miss any of them and the calculator above shows you which part fell short, and by how much.
Why it cannot go below zero
The same caps work the other way. A completion rate of 30% or worse makes a zero; under 3 yards an attempt makes b zero; no touchdowns makes c zero; and an interception on 9.5% of attempts or more wipes out d. Hit all four floors and the rating is 0.0 — the formula will not report a negative, however bad the afternoon.
This is passer rating, not ESPN's QBR
The number above is the traditional NFL passer rating, defined by the league and computed only from the five passing totals. It is a different thing from ESPN's Total QBR, which is a proprietary metric built from play-by-play data, adjusts for the situation and the defence, and runs on a 0–100 scale. QBR cannot be worked out from a box score, so this page does not claim to produce it.