How To Calculate A QB's Passer Rating

After hearing that Ben Roethlisberger passed for a perfect game last Thursday against the Rams, I was curious if their was a mathematical formula behind figuring out a Quarterback's ratings. Sure enough, there is.

There are online calculators that make figuring quarterback ratings simple, but if you want to know exactly how a QB's statistics translate into this number, this formula will take you through it step by step.

1. Divide a quarterback's completed passes by pass attempts.
2. Subtract 0.3.
3. Divide by 0.2 and record the total. The sum cannot be greater than 2.375 or less than zero.
4. Divide passing yards by pass attempts.
5. Subtract 3.
6. Divide by 4 and record the total. The sum cannot be greater than 2.375 or less than zero.
7. Divide touchdown passes by pass attempts.
8. Divide by 0.05 and record the total. The sum cannot be greater than 2.375 or less than zero.
9. Divide interceptions by pass attempts.
10. Subtract that number from 0.095.
11. Divide that product by 0.04 and record the total. The sum cannot be greater than 2.375 or less than zero.
12. Add the four totals you recorded.
13. Multiply that total by 100.
14. Divide by 6.
15. The final number is your quarterback rating.
    

So let's try this formula with Big Ben. His numbers on Thursday were

Passes Attempted - 20
Passes Completed - 16
Total Yards Passing - 261
Touchdowns - 3
Interceptions - 0

1. 16 / 20 = .80
2. .80 - 0.3 = .50
3. .50 / 2 = 2.5 (because the sum can not be greater than 2.375, the answer is actually 2.375)

4. 261 / 20 = 13.05
5. 13.05 - 3 = 10.05
6. 10.05 / 4 = 2.5125 (because the sum can not be greater than 2.375, the answer is actually 2.375)

7. 3 / 20 = .15
8. .15 / 0.05 = 3 (because the sum can not be greater than 2.375, the answer is actually 2.375)

9. 0 / 20 = 0
10. 0 - 0.095 = -.095
11. -.095 / 0.04 = -2.375

12. 2.375 + 2.375 + 2.375 + 2.375 = 9.5

13. 9.5 x 100 = 950

14. 950 / 6 = 158.3

Wow. I want to meet the guys that are able to keep up with this math throughout a whole game.