[Dante84]

How to calculate QBR

Here's how each metric is calculated (remember that no score can be lower than zero or higher than 2.375, no matter how well or how poorly the QB throws):

1. Completion percentage: Subtract 30 from the percentage of passes that are thrown for completions, then multiply by .05.

2. Yards per attempt: Subtract yards per passing attempt by three, then multiply by .25.

3. Touchdown percentage: Multiply the percentage of touchdown passes per passing attempt by .2.

4. Interception percentage: Multiply the percentage of interceptions per passing attempt by .25, then subtract that number from 2.375.

The scores for each category are added together. That sum is divided by six and multiplied by 100, which converts it into a rating on a scale from zero to 158.3. A putatively average QB would receive a rating of 66.7 (1 + 1 + 1 + 1 = 4, and 4/6 * 100 = 66.7).

Or, you can use this calculator.