Siding Calculator
Calculate how much siding you need for your home. Supports vinyl, fiber cement, and wood lap siding with cost estimates.
How to Calculate Siding for Your Home
To estimate siding, start by calculating the total exterior wall area of your house. Multiply the perimeter (2 times the length plus 2 times the width) by the wall height. Add the area of any gable ends, which are simplified as triangles (base times height divided by 2). Subtract the area of doors (about 21 sq ft each) and windows (about 15 sq ft each) to get the net area. Finally, add 10% for cutting waste and material overlap to arrive at the total siding needed.
Siding Types Compared
| Feature | Vinyl | Fiber Cement | Wood Lap |
|---|---|---|---|
| Cost per Square | $80 – $250 | $150 – $450 | $200 – $600 |
| Lifespan | 20 – 40 years | 30 – 50 years | 20 – 40 years |
| Maintenance | Low — occasional washing | Moderate — repaint every 10–15 years | High — repaint/stain every 5–7 years |
| Durability | Good; can crack in extreme cold | Excellent; resists rot and fire | Good; susceptible to rot and insects |
| DIY Friendly | Yes | Moderate — heavy and requires special tools | Yes — familiar woodworking skills |
What is a Square of Siding?
A "square" of siding is a unit of measurement equal to 100 square feet of coverage. Siding contractors and suppliers use squares to simplify ordering and pricing. For example, if your house has 2,000 sq ft of exterior wall area to cover, you need 20 squares of siding. Individual pieces are then calculated based on the coverage per piece for your chosen siding type.
Tips for Ordering Siding
- Always add 10–15% extra for cutting waste, especially around windows, doors, and corners.
- Order all materials from the same production lot to ensure consistent color and finish.
- Measure each wall individually if your house has bump-outs, bay windows, or irregular shapes.
- Do not forget to order trim, J-channel, starter strips, and corner posts along with the siding.
- Store siding flat and off the ground to prevent warping before installation.
- Check local building codes for requirements on house wrap, insulation, and fire rating.
- If you are installing wood siding, plan to stain or seal it after installation to protect against moisture and UV damage.
- While your exterior is exposed, consider updating your roofing at the same time to save on scaffolding and labor costs.
- Don't forget to plan your gutters too — use our gutter calculator to estimate materials.
Frequently Asked Questions
A 1,500 sq ft house typically has around 1,200 to 1,600 sq ft of exterior wall area depending on wall height, number of stories, and gable ends. After subtracting doors and windows and adding 10% waste, most single-story homes in this size range need 12 to 18 squares of siding. Use the calculator above with your exact measurements for a more accurate estimate.
Vinyl siding is generally the most affordable option, ranging from $80 to $250 per square for materials. It is also the easiest to install as a DIY project, which saves on labor costs. While vinyl is budget-friendly, fiber cement and wood lap siding offer greater durability and curb appeal at a higher price point.
Vinyl siding typically lasts 20 to 40 years depending on climate, quality of installation, and exposure to severe weather. Higher-grade insulated vinyl siding tends to last longer. Vinyl requires minimal maintenance — occasional power washing is usually all that is needed to keep it looking fresh. However, it can crack in extreme cold and may fade over time with prolonged sun exposure.
In some cases, new siding can be installed over existing siding, but it is not always recommended. Installing over old siding can trap moisture, hide underlying damage like rot or mold, and add extra weight to the wall structure. Most professionals recommend removing the old siding first, inspecting the sheathing and house wrap, and making repairs before installing new siding for the best long-term results.
DIY siding costs depend on your house size and siding type. For a typical 2,000 sq ft exterior, vinyl siding materials run $1,600 to $5,000, fiber cement costs $3,000 to $9,000, and wood lap costs $4,000 to $12,000. Add $300 to $800 for house wrap, trim, J-channel, and accessories. DIY installation eliminates labor costs, which typically account for 50–65% of a professional siding project. You will also need basic tools like a circular saw, tin snips, and a level.