CALCULATION METHOD
How much siding do I need?
Multiply each rectangular wall’s width by height. Add triangular gables using one-half of base width times gable height. Subtract only the door and window area you intend to exclude, then add the selected waste allowance.
Wall area = wall length × wall height × matching walls
Gable area = ½ × gable width × gable height × matching gables
Order area = (wall area + gable area − openings) × (1 + waste)
One siding square = 100 sq ft
Siding calculator example
Four 40 × 10 ft wall sections plus two 40 × 8 ft triangular gables total 1,920 sq ft. After deducting 240 sq ft of large openings, the net area is 1,680 sq ft. Adding 10% waste gives 1,848 sq ft, or 18.48 siding squares.
Vinyl siding calculator
Vinyl siding is commonly ordered by area or carton. Enter the actual coverage per panel and carton from the product label. The calculator rounds panels and cartons up, because partial packages may not be available.
Siding square footage calculator
A “square” is an ordering unit equal to 100 sq ft. The tool shows both exact square footage and squares, so you can compare supplier quotes that use different units.
House siding calculator with windows and doors
Industry measuring guidance often includes ordinary windows and doors as a built-in allowance for cuts. This tool lets you choose: enter zero to keep all openings included, or deduct only very large doors and windows when appropriate.
Siding cost calculator
Choose price per carton, per square, or per square foot. The total covers siding only; it excludes labor, delivery, tax, sheathing, housewrap, flashing, trim, soffit, fascia, fasteners, caulk, equipment, disposal, and permits.
Vinyl Siding Institute installation manual for rectangular and triangular area measurements, the 100 sq ft square, openings, starter strip, and waste planning; CertainTeed estimating guidance for wall and gable formulas and a 10% large-project waste allowance. Accessed September 11, 2026.