The Rating Percentage Index (RPI) has been used by the NCAA men's basketball committee since 1981, and officially by the women's basketball committee since 1984, as supplemental data to help select at-large teams and seed all teams for the men's and women's NCAA basketball tournaments. The NCAA did not make the RPI available to member institutions and to the public in-season until the 2005-06 season, when it began doing so on a weekly basis in a bare-bones fashion. Before then, the data were kept confidential within the committees. Collegiate Basketball News duplicates the RPI that is generated by the NCAA to four decimal places using available formulas without input from the NCAA. The three component factors which make up the RPI are as follows:

Factor I is the team's Division I winning percentage and is 25 percent of the RPI. Games against non-Division I opponents are not included in the normal RPI. For the men, beginning in 2004-05, and for the women, beginning in 2011-12, home wins are weighted 0.6, neutral wins 1.0, and road wins count 1.4, and road losses are 0.6, neutral losses 1.0, and home losses 1.4.

Factor II is the team's opponents' Division I winning percentage, or the team's schedule strength, excluding results against the team in question. It is 50 percent of the RPI.

Factor III is the team's opponents' opponents' Division I winning percentage, or the team's opponents' strength of schedule, excluding results against the team in question. Factor III is 25 percent of the RPI.

No longer in use is Factor IV, which was the bonus/penalty portion of the RPI. It was used in conjunction with the above three Factors and was called the Adjusted RPI. it was used for the men from 1993-94 through 2003-04 and for the women from 1993-94 through 2010-11. Factor IV first started with the "normal" RPI as derived by Factors I, II and III above, and bonus and penalty points were then awarded in two different categories. The first was based on the team's non-conference schedule using the normal RPI ranking of the team's opponents. Bonus and penalty points in the second category were based upon winning games against top 50 teams in the RPI, and on losing to teams ranked lower than 150 in the RPI. Bonus and penalty points in the second category varied based upon the location of the game and were cumulative. A loss to a non-Division I team resulted in penalty points. The Adjusted RPI was first published in The RPI Report and The Women's RPI Report during the 1998-99 season.