|Not the actual calculator I use.|
Find it here (or in the "Regional Rankings" tab in the upper link bar).
Also, for the first time this year, I'm running D3-wide RPI numbers. These include all Division III games (and only Division III games) and don't include any SOS weighting. Also included in the list are non-conference RPI numbers for each team.
Find it here (or in the "D3 RPI" tab in the upper link bar).
Both sections will be updated periodically (as I have time), but the frequency usually increases as we get later into the season (or if Calvin is nearer the top).