How this calculator works
The calculator multiplies average window width by height and window count to estimate total opening area. Perimeter trim is based on two widths plus two heights for each fully trimmed window. Trim order adds waste, and sealant tubes are rounded up from perimeter length divided by coverage per tube.
Example: eight 36 inch by 48 inch windows have 96.0 square feet of opening area. The full perimeter is 112.0 linear feet. With 10% waste, trim order is 123.2 linear feet, and 25 feet per tube rounds to 5 tubes.