Enter the team’s winning percentage, the team’s opponents’ winning percentage, and the team’s opponent’s opponents’ winning percentage to determine the RPI.

RPI Formula

The following formula is used in NCAA basketball to calculate a rating percentage index (RPI). 

RPI = .25 * WP + .5 * OWP + .25 * OOWP
  • Where RPI is the rating percentage index
  • WP is team’s winning percentage
  • OWP is the team’s oppenents’ winning percentage
  • OOWP is the team’s oppenent’s oppenents’ winning percentage

The last two portions of this formula are considered the team’s strength of schedule.

In all cases, the winning percentages should be the average of all teams. For example, if a team played opponents with winning percentages of 50% and 100% the average would be 75%.

RPI Definition

RPI, short for rating percentage index, is a metric used in college basketball, and sometimes the NBA, to rank or determine the strength of a team based on their winning percentage and their strength of schedule.

The strength of schedule (SOS), as mentioned above, includes both the team’s direct opponent winning percentages and the winning percentage of their opponent’s opponents.

Example Problem

How to calculate RSI?

First, determine the team’s winning percentage for this example, the team has won 75% of their games.

Next, determine the team’s opponent’s average winning percentage. In this case, this is found to be 60%.

Next, determine the average winning percentage of the opponent’s opponents. For this example, this winning percentage is 40%.

Finally, calculate the RPI using the formula above:

RPI = .25 * WP + .5 * OWP + .25 * OOWP

RPI = .25 * 75 + .5 * 60+ .25 * 40

RPI = 58.75