Siding Calculator

What Is Siding? Types, Performance, and Choosing the Right Material

This siding calculator estimates squares, panels, trim, and material cost for any exterior wall covering project. Siding (also called cladding or exterior wall covering) is the system of materials applied to the outside of a building to protect it from weather, add insulation, and define its exterior appearance. Siding is the first line of defense against rain, wind, UV radiation, and insects — and it accounts for roughly 5–10% of a home's total value. A full siding replacement is one of the most impactful exterior renovation projects, with typical cost recovery of 70–80% at resale.

Common siding materials compared:

• Vinyl lap siding — the most popular choice in the US; low maintenance (never needs painting); $60–$120 per square for material; impact-resistant versions available for hail-prone regions; lifespan 20–40 years; does not rot but can crack in extreme cold or fade over time; thickness 0.040–0.055 inches (thicker = better quality)
• Fiber cement (James Hardie, Nichiha) — cement, sand, and cellulose fiber composite; fireproof, rot-proof, and pest-resistant; $120–$200 per square; requires painting every 10–15 years; excellent in coastal environments; lifespan 30–50 years; the fastest-growing siding category by market share
• Engineered wood (LP SmartSide) — OSB-based panel with resin coating; looks like real wood without the maintenance; $80–$150 per square; 50-year warranty from major brands; susceptible to moisture if damaged or improperly installed
• Cedar lap siding — natural rot and insect resistance; beautiful grain and accepts stain well; $200–$400 per square; lifespan 20–30 years with maintenance; not recommended in very wet climates without proper priming and painting schedule
• Board-and-batten — wide vertical boards with narrow cover strips; available in wood, fiber cement, and vinyl; distinctive farmhouse / modern barn aesthetic; typically $150–$300 per square in fiber cement
• Stucco (three-coat) — cement-based exterior plaster; common in the Southwest and Florida; excellent durability in dry climates; can crack in freeze-thaw climates without expansion joints; $6–$10 per sq ft installed

IRC Section R703 requires a weather-resistant barrier (housewrap or building paper) beneath all cladding types. Wood siding must maintain 6 inches of clearance above grade (R703.4). Fiber cement must be installed per manufacturer instructions and painted within 180 days of installation to maintain warranty coverage.

How to Use This Siding Calculator

Enter your building length, width, and wall height to get instant results — net wall area, squares needed, and an optional material cost estimate. The calculator deducts door and window openings, adds your chosen waste factor, and supports both imperial and metric inputs. If your house has gable ends (most do), check the "Include gable ends" option and enter the gable height so the triangular area above the eave is counted. Use the siding type selector to see the typical exposure for your chosen profile. For painting over new siding, see the paint calculator to estimate gallons and coats.

How to Calculate Squares of Siding

Calculating siding starts with gross wall area, then subtracts openings, adds waste, and converts to squares:

1. Gross area — multiply the perimeter (2 × length + 2 × width) by the wall height
2. Gable area — if applicable, add 0.5 × width × gable height for each gable end (typically 2)
3. Deduct openings — subtract 21 sq ft per standard door and 15 sq ft per standard window
4. Add waste — multiply by 1.10 for a 10% waste factor
5. Convert to squares — divide by 100 and round up to the nearest whole square

For a 40 × 30 ft house with 9 ft walls, 2 doors, and 4 windows: gross wall = 2 × (40 + 30) × 9 = 1,260 sq ft. Deduct doors (42 sq ft) and windows (60 sq ft) = 1,158 sq ft net. With 10% waste = 1,274 sq ft ÷ 100 = 13 squares needed.

Siding Types and Exposure Widths

The siding type affects exposure width (the visible face between courses) and installation complexity, but not the area formula:

• Lap siding — the most common residential profile; horizontal boards overlap each other with a 4–5 inch exposure. Works on virtually any house style and is available in vinyl, wood, fiber cement, and engineered wood.
• Cedar shake / shingle — hand-split or sawn wood shakes with a 6–7 inch exposure give a natural, textured look. More expensive than vinyl but highly durable when properly maintained.
• Panel / T1-11 — large-format plywood or OSB panels (typically 4 × 8 ft) installed vertically with shiplap or grooved edges. Common on garages, sheds, and utility buildings. No exposure concept — panels cover full height.
• Board-and-batten — wide vertical boards (typically 8–12 inches) with narrow 1½–2 inch battens covering the joints. Popular in farmhouse, craftsman, and modern barn styles. Use 15% waste due to vertical cuts around openings.

Siding Cost Estimate

Material costs per square vary significantly by product type and region. Here are typical 2026 ranges for DIY material purchases:

• Vinyl lap siding — $60–$120 per square; low maintenance, available in dozens of colors
• Fiber cement (HardiePlank) — $120–$200 per square; fire-resistant, paintable, 30+ year lifespan
• Cedar lap / shake — $200–$400 per square; natural wood aesthetics, requires periodic staining
• Engineered wood panel (T1-11) — $80–$150 per square; economical choice for outbuildings
• Board-and-batten (fiber cement) — $150–$300 per square

Labor adds another $50–$150 per square depending on complexity, local rates, and the number of floors. If you're replacing old siding, add $30–$80 per square for removal and disposal. For a roof-to-foundation project cost, combine your siding estimate with the roofing calculator to get a full exterior material budget.

How Much Waste Factor to Add

The waste factor compensates for material lost to cuts, trim pieces, and the occasional damaged board. Standard guidance by siding type:

• 10% — standard for lap, vinyl, and panel siding on simple rectangular walls
• 12–15% — board-and-batten, shake, or any house with dormers, bay windows, or complex angles
• 15–20% — diagonal lap or patterns that require precise angle cuts at every corner

It is nearly always better to order slightly more than needed. Most siding manufacturers will not accept returns on cut or partial boxes, and matching a color from a different production run years later can be difficult.

Siding and the IRC — Code Minimums to Know

IRC Section R703 governs exterior wall covering for residential construction. Key requirements relevant to siding selection include:

• A weather-resistant barrier (housewrap or building paper) is required under all cladding types
• Fiber cement must be installed per manufacturer instructions and maintained with paint or coating
• Wood siding must maintain a minimum 6 inches of clearance above grade and 2 inches above roofing
• Panel siding (T1-11) used as structural sheathing must meet minimum thickness requirements per the IRC span tables
• All siding must be installed with corrosion-resistant fasteners appropriate for the material

Always verify requirements with your local building department — energy code amendments may require a continuous insulation layer under the cladding in some jurisdictions, which affects nailing patterns and furring strip requirements.