Siding Calculator

A siding order starts with geometry, not a generic house size. This calculator turns one entered wall run and common wall height into a gross rectangular wall area, deducts the window and door inputs you provide, applies your stated allowance, and converts that result into editable purchase units. It is useful for making the arithmetic visible before talking to a supplier.

That scope is deliberately narrower than an exterior-wall design. A siding panel count cannot tell you whether the existing sheathing is sound, where flashing belongs, how a weather-resistive barrier should be integrated, which trim profile is compatible, what a product's wind or fastening requirements are, or whether a wall has moisture damage. The Vinyl Siding Institute installation manual makes the same practical point: current manufacturer instructions and local requirements can change the work. Use this page to create a transparent quantity record, not to replace those documents.

For a simple area cross-check before you begin a cladding takeoff, use the Square Footage Calculator. Keep its result separate from this calculator's product, opening, and accessory assumptions.

The main form accepts a total wall run and one wall height. That is appropriate only when the wall segments in that run share the same vertical height. Before entering a number, sketch each elevation and split it wherever the shape changes: a gable, step, bump-out, return, dormer, bay, sloped grade line, porch interruption, or different cladding material should have its own area line.

1. Record each simple rectangle. Measure its horizontal run and finished cladding height.
2. Record non-rectangular zones separately. A triangular gable, for example, needs its own measured geometry rather than an average wall height.
3. Record openings from the actual elevation. The calculator uses a count and average width and height. If windows differ substantially, keep a separate opening schedule and reconcile the total before treating the deduction as final.
4. Mark every transition. Corners, doors, windows, material changes, roof-to-wall intersections, and lower-wall details can change trim or flashing needs even if they do not change net cladding area.

Taking this extra minute avoids a common bad estimate: multiplying the entire perimeter by the tallest wall, then hoping a large allowance will hide the error. An allowance is for a stated purchasing reason; it is not a substitute for missing geometry.

For the consistent wall zone you enter, the calculator uses straightforward area arithmetic. It converts the wall run and height to feet, then calculates gross area and opening deductions:

It displays siding squares from the raw net area, using the calculator convention of 100 sq ft per square. It then applies the allowance only to the material purchase calculation:

The round-up matters: a partial panel or plank still requires a full purchase unit. The coverage field is editable because real products vary by profile, installed exposure, length, packaging, and manufacturer. Treat the field as a place to copy the exact product's documented coverage, not as a universal value.

The vinyl, fiber-cement, wood, and metal modes set editable coverage and allowance starting points so the form is usable. They are not product claims. A lap-siding product's usable coverage depends on its profile and installed exposure; panel systems can depend on panel dimensions, joint layout, trims, and waste; metal systems can have profile-specific coverage. Current manufacturer installation and technical documents are the source for the product actually selected.

Choose an allowance for an identifiable reason: a documented cut pattern, non-reusable offcuts, a gable or stepped layout, a required color match, an approved repair-stock policy, or the exact supplier package size. Do not use a percentage to cover unknown wall damage, missing flashing details, or an unmeasured elevation. If the project changes from a simple rectangular takeoff to a wall with many openings and transitions, remeasure the zones first and then decide whether the purchase allowance should change.

The calculator rounds the purchase-unit output up after the allowance. That makes the input auditable: someone reviewing the order can see the net area, the allowance, the coverage copied from the product, and the final round-up separately.

The house-wrap control estimates rolls from gross wall area only. It cannot determine whether a particular wall needs a specific weather-resistive barrier, drainage plane, flashing tape, cap flashing, trim detail, air-sealing approach, or repair before cladding goes on. Those decisions depend on the selected products, existing wall condition, climate, local requirements, and the complete wall assembly.

For example, DuPont's current single-family WRB and flashing guidance describes one named system and its own conditions. It should not be generalized into instructions for every wrap or every siding product. Before placing an order, record the selected wall-detail documents and ask the responsible project parties to resolve any existing water, rot, pest, structural, or code questions.

If exterior wall work affects an opening, roof edge, or drainage item, review related quantities separately with the Gutter Calculator and Roofing Calculator. Neither tool designs the intersection between those systems.

The cost panel multiplies numbers you enter. In the current arithmetic, the material rate applies to squares after the stated allowance; the labor and tear-off rates apply to raw net squares; the trim rate applies to the calculator's preliminary linear-foot total; wrap, delivery, and other entries are added only when you supply them. That makes the result reproducible, but it does not make it a supplier or contractor quote.

Keep the exact product, coverage, allowance, supplier price date, delivery terms, tax treatment, labor scope, removal scope, repair allowance, and excluded items next to each cost line. A broad total can conceal expensive work such as sheathing repair, flashing changes, scaffolding, lead-safe practices, permits, disposal, or access constraints. A dated, line-by-line record is more useful than a falsely precise total.

For a separate finish-area estimate after the cladding plan is established, use the Paint Calculator. It does not determine whether or when a selected siding product may be painted.

Do not use this calculator to choose a siding product, diagnose moisture or structural damage, select fasteners, define clearances, design flashing or a weather-resistive barrier, establish wind resistance, choose trim details, decide whether old cladding can remain, or approve construction. Those are wall-system and site-specific decisions, not area arithmetic.

1. Recheck every wall zone, opening, and unit before changing the allowance.
2. Copy coverage and stock lengths from the selected product's current documentation.
3. Keep cladding, trim, weather-resistive barrier, flashing, fasteners, repairs, and disposal on separate order lines.
4. Confirm supplier packaging, color availability, and delivery terms before purchase.
5. Resolve wall-condition, safety, permit, and local-requirement questions with the responsible project parties.

If a field, formula, or result appears unclear, use the page's Report an issue option. The site team can investigate the calculator behavior, but cannot approve an exterior-wall design or installation.