What is passer rating?

NFL passer rating combines four passing measures: completion percentage, yards per attempt, touchdown percentage, and interception percentage. Its capped formula produces a rating from 0 to approximately 158.3.

It is a passing-efficiency measure, not a complete evaluation of quarterback play. It does not directly include rushing, sacks, or fumbles, and it is not a percentage: a rating of 100 does not mean every pass was completed. College football uses a different passing-efficiency formula.