Siding Calculator

Measure the width and height of each wall face and add a section for it. For an irregular building outline, add one section per rectangular wall face — the calculator sums their areas automatically before any rounding happens.

A gable-end wall is a rectangle (the wall up to the eave line) plus a triangle (the gable, from the eave line up to the peak) sitting on top of it. Measure the width once, the wall height to eaves for the rectangle, and the gable height — vertical distance from the eave line to the peak — for the triangle. The calculator combines both into one gross area for that wall.

Add each opening's width, height, and quantity inside its wall using “Add opening.” The calculator multiplies width × height × quantity and subtracts the total from that wall's gross area — a wall can have any number of openings, and a garage door is simply another rectangular opening.

This calculator subtracts only the openings you enter. Some estimating methods simplify takeoffs differently, so if your siding product's manufacturer provides project-specific estimating guidance, follow that guidance.

Material allowance is an editable planning margin for cuts and installation variation, applied once to the combined net project area. CertainTeed's own consumer siding-estimating guidance suggests allowing about 10% extra, which is this calculator's default — adjust it for your product, project complexity, and any specific guidance from your siding's manufacturer.

A siding square is 100 ft² — a standard siding-industry planning unit. This calculator shows your siding-to-buy figure as a decimal number of squares (for example, 19.25 squares) for easy communication with a supplier or contractor. It does not round that figure up to a whole purchase quantity — use package planning below if your specific product is sold in discrete packages.

Siding products are packaged differently — cartons, bundles, boxes of boards — and coverage varies by manufacturer and profile. This calculator does not assume a package size for you: enter your product's actual stated coverage per package, and it divides your siding-to-buy figure by that coverage, rounding up to a whole package.

Add one section per wall or gable end — front, back, sides, an addition, a garage gable. Each wall's net area (gross area minus its own openings) is calculated in full, all walls are added together at full precision, and only then is the material allowance applied once to the combined total. Nothing is rounded wall-by-wall along the way.

Vinyl, fiber cement, engineered wood, wood, and metal siding all use the same wall-area geometry in this calculator. Product-specific installation, coverage, and accessory requirements vary by manufacturer and profile, which is why the calculator asks for your product's actual package coverage instead of a material-type selector that wouldn't change the underlying math anyway.

• Structural wall design, framing, or sheathing requirements.
• Weather-resistive barrier, drainage plane, or flashing design.
• Fastening schedules or wind-load requirements.
• Starter strip, J-channel, corner trim, or other accessories.
• Fasteners or house wrap quantity.
• Soffit or fascia material — see the Soffit Calculator.
• Labor, tear-off/removal, disposal, delivery, or taxes.
• Building code or manufacturer installation compliance.

Follow your project drawings, manufacturer installation instructions, and a qualified professional for all of the above — this calculator estimates siding material quantity only.

Use this calculator for exterior wall siding material. Use the Soffit Calculator for soffit panels and attic ventilation at your eaves — the two are kept separate so neither double-counts or mixes up the other's material.