Quartback rating formula
First figure these four components
* (Percentage of completions - 30) x 0.05
If the number is less than 0, award 0. If the number is greater than 2.375, award 2.375.
* (Average yards gained per attempt - 3) x 0.25
If the number is less than 0, award 0. If the number is greater than 2.375, award 2.375.
* Percentage of touchdown passes x 0.2
If the number is greater than 2.375, award 2.375.
* 2.375 - (Percentage of interceptions x 0.25)
If the number is less than 0, award 0.
Add the four numbers together, divide by 6, multiply by 100.
Which I guess explains why QB ratings can be over 100. A completely meaningless statistic as it ignores leadership and play calling.
For the record:
To gain a 2.375 in completion percentage, a passer would have to complete 77.5 percent of his passes. The record is 70.55.
To earn a 2.375 in percentage of touchdowns, a passer would have to achieve a percentage of 11.9. The record is 13.9.
To earn a 2.375 in percentage of interceptions, a passer would have to go the entire season without an interception.
To earn a 2.375 in percentage of average yards, a passer would have to average 12.50 yards. The record is 11.17