Counting only quarterbacks who have played more than one full year (you'd be amazed at how many short-lived QBs there are), the average career length of an NFL quarterback is 6.6 years.
Source: http://www.pro-football-reference.com/players/qbindex.htm
The professional life of an NFL quarterback is short. The average length of an NFL quarterback's career is only 4.4 years.
Including all player positions, the average NFL career is four seasons.
37
10
Including all player positions, the average NFL career is four seasons.
Four years
6 years
The average career of an NFL player is 3 1/2 seasons according to the NFLPA.
8 to 11 years
Tom Brady
Brett Farve, with about 6,300 completed passes in his NFL career.
23 million