Siding Calculator

How to Use This Siding Calculator

Measure each exterior wall's width and height in feet. For each wall, estimate the total opening area (windows + doors). For example, a wall with two 3×5 ft windows and one 3×7 ft door has 30 + 21 = 51 sq ft of openings. Enter all four walls, choose your siding material, and the calculator will determine how many squares (1 square = 100 sq ft) and pieces you need — including waste factor for gable-end cuts and starter strips.

Siding Your Home: A Complete Guide to Materials, Costs, and Installation

Siding is your home's first line of defense against weather — and its most visible design element. A siding replacement typically returns 75-85% on resale (Remodeling Magazine Cost vs. Value Report), making it one of the best exterior renovations you can do. But choosing the right material and getting the quantity right makes a six-figure difference over the life of your home. Here's what you need to know.

Understanding "Squares" — The Unit That Confuses Everyone

Siding is sold by the square — one square covers 100 square feet of wall area. This is different from roofing squares (which are also 100 sq ft but measured differently due to pitch). A typical single-story 2,000 sq ft house needs roughly 18-22 squares of siding, depending on the floor plan complexity, number of windows, and gable geometry. To estimate: measure the perimeter of your house × wall height, subtract all openings, add 10% for waste (15% for complex gables), and divide by 100. The calculator above does this for up to 4 walls automatically.

Siding Materials Compared: Cost, Lifespan, and Maintenance

• Vinyl Siding: $300-500 per square installed. Lifespan 20-40 years. Nearly zero maintenance (occasional power washing). Fades over time and can crack in extreme cold. Available in dozens of colors — but can't be painted. The most popular siding in America for a reason: lowest installed cost and virtually maintenance-free. Look for "insulated vinyl" (adds R-2 to R-3 to wall R-value) if you're in a cold climate.
• Fiber Cement (HardiePlank): $500-800 per square installed. Lifespan 50+ years. Looks like real wood but resists rot, insects, and fire. Requires repainting every 10-15 years. Heavier and harder to install than vinyl (requires special saw blades — the silica dust is hazardous). The premium choice for "forever homes."
• Wood Siding (Cedar Lap / Shiplap): $600-1,200 per square installed. Lifespan 20-40 years with proper maintenance. The most beautiful option — nothing looks like real wood grain. However, it needs painting/staining every 5-7 years, is vulnerable to woodpeckers and carpenter bees, and rots if not properly flashed. Best for historic homes and high-end builds where the look justifies the upkeep.
• Metal Siding (Steel / Aluminum): $500-900 per square installed. Lifespan 40-60 years. Fireproof, insect-proof, and impervious to rot. Aluminum won't rust but dents easily; steel is stronger but can rust if the coating is scratched. Modern metal siding comes in wood-grain finishes and vertical panel profiles that look nothing like the old barn metal.
• Engineered Wood (LP SmartSide): $400-600 per square installed. Lifespan 30-50 years. Wood strands bonded with resin and zinc borate — looks like real wood, cuts like OSB, resists rot better than natural wood. A strong mid-range competitor to fiber cement at a lower price point.

How to Measure Your House for Siding (Step by Step)

Accurate measurements prevent the two most expensive mistakes: ordering too little (project stalls mid-install) and ordering too much (wasted material you can't return). Here's the contractor's method:

1. Draw a simple floor plan sketch of each exterior wall. Doesn't need to be architectural quality — rectangles with measurements are fine.
2. Measure each wall's length and height. For gable ends (triangular portions), multiply width × height at the tallest point and divide by 2.
3. Measure and list every opening: windows, doors, garage doors, vents. Multiply each width × height and sum them by wall.
4. Wall net area = (width × height) − total openings. Do this for every wall and sum.
5. Add waste factor: 5% for simple rectangular walls, 10% standard, 15% for complex roofs with many dormers and gables.
6. Divide by 100 to get squares. Round up to the nearest 0.1 square — not the nearest whole square (siding is sold in partial squares).

Hidden Costs in Siding Projects

The siding material cost is only 40-50% of the total project. The rest goes to items many homeowners overlook:

• House wrap (Tyvek or similar): $0.50-1.00 per sq ft. Required behind all siding types as a weather barrier. If your old house wrap is torn or missing, factor in full replacement.
• Trim, corners, J-channel, starter strips: $200-800 depending on house size. These accessories are essential and brand-specific. Vinyl siding accessories alone can add 10-15% to the material cost.
• Old siding removal and disposal: $1,000-3,000. If you have old asbestos-cement siding (common in 1940s-1960s homes), asbestos abatement adds $3,000-10,000 and requires licensed contractors.
• Sheathing repair: $500-2,000. Once old siding comes off, rotted OSB or plywood sheathing often reveals itself. Budget for at least 2-3 sheets of repair unless you know the sheathing is sound.
• Permits: $100-500. Most municipalities require a building permit for siding replacement. Your contractor should pull this, but verify.

DIY vs Professional Installation

Vinyl siding is the most DIY-friendly option — it's lightweight, cuts with tin snips or a circular saw, and clips together with a built-in locking edge. A handy homeowner with a helper can side a single-story house in 2-3 weekends. Fiber cement is less DIY-friendly: it's heavy (2.5 lbs per sq ft), creates carcinogenic silica dust when cut, and requires special fasteners and joint flashing. Wood siding requires carpentry skill for proper laps, mitered corners, and flashing integration. Metal siding requires specialized tools for cutting and bending trim. For any multi-story house, professional installation is strongly recommended — the safety risk of working on ladders and scaffolding for days is not worth the labor savings.