When to use: The grid (borrow-pit) method estimates earthwork volumes on a site divided into square cells. At each grid node the cut/fill depth = existing − proposed elevation (positive = cut, negative = fill). For each cell, the four corner depths are averaged and multiplied by the cell area to get its volume. Positive cell volumes sum to total cut, negative to total fill. A shrink/swell factor inflates the compacted fill volume to the bank volume of cut required, so the net balance reflects real haul.