The Football Power Index (FPI) is a predictive rating system developed by ESPN that measures team strength and uses it to forecast game and season results in American football. Each team’s FPI rating is composed of predictive offensive, defensive, and special teams value, as measured by a function of expected points added (EPA). That rating is the basis for FPI’s game-level and season-level projections. FPI accounts for team strength, opponent strength, and home-field advantage, and there are a number of unique inputs into each game prediction. FPI’s rating is based on the average number of points by which a team would beat an average NFL (or college) team on a neutral field. The model uses a Bayesian framework, using priors around the EPA rate of each team unit, derived from preseason expectations.

FPI is used to rank college football teams and NFL teams based on their strength and performance. ESPN publishes weekly rankings based on FPI for both college football and NFL. FPI rankings are based on simulations of the rest of the season using FPI, results, and remaining schedule.

However, FPI, along with other metrics from ESPN, has been criticized for its inaccuracy, relying more on probabilities and less on in-game action. For example, in the 2015-2016 college football playoff, FPI listed the Oklahoma Sooners as the team with the highest chance to win the playoff at 39%, while the Clemson Tigers were listed at third highest at 17%. Clemson would go on and beat Oklahoma in the first round, but eventually lose to Alabama in the national championship game.