The NFL rates its passers for statistical purposes against a fixed performance standard based on statistical achievements of all qualified pro passers since 1960. The current system replaced one that rated passers in relation to their position in a total group based on various criteria.

The current system, which was adopted in 1973, removes inequities that existed in the former method and, at the same time, provides a means of comparing passing performances from one season to the next.

It is important to remember that the system is used to rate pass- ers , not quarterbacks. Statistics do not reflect leadership, play-calling, and other intangible factors that go into making a successful professional quarterback.

Four categories are used as a basis for compiling a rating:
  Percentage of completions per attempt.
  Average yards gained per attempt.
  Percentage of touchdown passes per attempt.
Percentage of interceptions per attempt.

The average standard, is 1.000. The bottom is .000. To earn a 2.000 rating, a passer must perform at exceptional levels, i.e., 70 percent in completions, 10 percent in touchdowns, 1.5 percent in interceptions, and 11 yards average gain per pass attempt. The maximum a passer can receive in any category is 2.375.

In order to make the rating more understandable, the point rating is then converted into a scale of 100. In rare cases, where statistical performance has been superior, it is possible for a passer to surpass a 100 rating.