Siding square footage formula
net area = wall length × height + gables − openingssiding squares = purchase area ÷ 100 ft²The calculator adds the selected waste allowance before converting the order to squares and cartons.
Siding calculator
Estimate siding area, 100-square-foot squares, and full cartons for walls and gables.
Enter the exterior measurements
Add the lengths of walls with the same average height; enter triangular gables as a combined area.
Net wall area is only the field siding
The result subtracts entered openings and converts the remaining wall area to squares and cartons. Starter strip, trim, corners, channels, flashing, soffit, fascia, fasteners, and waste from short wall segments remain separate.
- Measure each gable and wall plane once.
- Use manufacturer carton coverage for the chosen profile.
- Plan laps, panel direction, and matching production lots before ordering.
Separate irregular walls
Calculate wall sections with different heights separately. For a triangular gable, multiply base by height and divide by two. Confirm installation details and exposure with the manufacturer.