An AutoCAD calculation would be WAY more accurate. The algorithm used on the Pool Chart is my own, and makes the following assumptions:

1. Break begins 1/3 of the distance from the shallow to the deep end.
2. Hopper bottom (straight slopes) rather than bowl bottom.
3. Actual water level is 6" below listed depths.

It does not account for a 4" - 6" shelf around the deep end.

Pool salesmen consistently over-estimate pool volumes, as a sales tool.