- How much siding do I need for my house?
- What is a square of siding?
- How many squares of siding do I need for a 2,000 sq ft house?
- How do I measure gable ends for siding?
- How much does vinyl siding cost per square?
- How many boxes of siding do I need?
- Do I subtract windows and doors when calculating siding?
- How much extra siding should I buy for waste?
- How much siding do I need for a 1,500 sq ft house?
- Vinyl vs fiber cement: which costs more per square?
Measure each wall’s length times its height, add the gable areas (half the base times the height), then subtract 20 square feet per door and 15 per window. Divide the net area by 100 to get squares, the unit siding is sold in, and add 10 percent for waste. A 40 by 30 foot house needs about 14 squares.
Siding Calculator
How many squares, cartons, and dollars does your siding job need?
Siding is sold by the square (100 sq ft). Vinyl cartons are the standard package of about 200 sq ft, so the carton count is a vinyl equivalent. Fiber cement and wood are usually sold by the plank or bundle, so confirm coverage per package with your supplier. The waste allowance covers offcuts, angled gable cuts, and mis-cuts.
A square is the unit the siding industry runs on. One square equals 100 square feet of finished wall coverage, and manufacturers such as CertainTeed and James Hardie estimate, price, and package their products around it. Contractors quote per square, suppliers stock per square, and the calculator above thinks in squares too. Get the square count right and the rest of the project, cartons, trim, and budget, falls into place.
How to Use This Siding Calculator
- Enter up to four walls. Length times height in feet for each. The defaults show a typical 40 by 30 foot house; change them to your measurements or zero out walls you do not have.
- Add your gables. Enter how many triangular gable ends you have plus one base and height. Each gable counts as base times height divided by 2.
- Count doors and windows. The calculator subtracts 20 square feet per door and 15 per window automatically.
- Pick a siding type, set waste, and hit calculate. You get the net area, the squares to order, the carton count, and an optional material cost.
What Each Input Means
- Walls: Measure the full length of each exterior wall at the ground and the height from the foundation to the eaves. Do not deduct anything yourself; the openings step handles that.
- Gables: The triangular wall section under each roof peak. Measure the base (the wall width) and the vertical rise from the eaves line to the peak.
- Doors and windows: Standard deductions of 20 and 15 square feet. They are averages, not exact, and they keep the math simple for a planning estimate.
- Siding type: Changes the packaging note under your result. The square count is the same for every material; only how it ships differs.
- Waste %: Covers offcuts, angled gable cuts, bad pieces, and mis-cuts. Ten percent suits a simple house; complex shapes need more.
The Formula and Methodology
The calculator follows the same sequence siding contractors and suppliers use when they estimate by the square:
- Wall area: length times height for each wall, added together.
- Gable area: number of gables times (base times height divided by 2).
- Openings: doors times 20 plus windows times 15, subtracted from the total.
- Squares: net area times (1 plus waste) divided by 100, rounded up. Suppliers sell whole squares, so a fraction always rounds up.
- Cartons: squares divided by 2, rounded up. A standard vinyl carton covers about 200 square feet, which is 2 squares.
The square as a unit is universal in the trade. CertainTeed’s vinyl siding resources and James Hardie’s fiber cement documentation both estimate and price in squares, which is why quotes, supplier stock, and this calculator all speak the same language. One caveat from the box itself: carton coverage varies by profile, with most vinyl cartons landing between 100 and 200 square feet, so check the label on your chosen product and treat the carton count here as a planning figure.
Siding Types at a Glance
Costs are typical 2026 US material-only ranges per square, not installed prices and not quotes.
| Type | How it is sold | Material per square (2026 typical) | Notes |
|---|---|---|---|
| Vinyl | Cartons, usually 200 sq ft (2 squares) | $100 – $300 | Most common in the US; light, DIY-friendly, 20 to 40 year life |
| Fiber cement | Planks (e.g. 12 ft boards) | $200 – $500 | Fire resistant, wood-like look; heavy, needs repainting every 10 to 15 years |
| Wood (cedar) | Bundles | $300 – $600 | Classic look; needs staining or painting every 3 to 7 years |
| Engineered wood | Planks or panels | $250 – $450 | Pre-primed, lighter than fiber cement; mid-range option |
Openings Deduction Reference
| Opening | Deduction used | Note |
|---|---|---|
| Standard entry door | 20 sq ft | Covers a 3 by 6 ft 8 in door plus trim |
| Standard window | 15 sq ft | Covers a typical 3 by 5 ft window |
| Sliding glass door | Measure it | Often 40 to 50 sq ft; too big for the standard deduction |
| Garage door | Measure it | A double garage door can exceed 110 sq ft |
| Large picture window | Measure it | Any opening much bigger than standard deserves its own math |
Waste Allowance by House Complexity
| House shape | Suggested waste | Why |
|---|---|---|
| Simple rectangle, few openings | 10% | The default; mostly straight cuts |
| Gables, bump-outs, several corners | 12 – 15% | Angled gable cuts waste the most material |
| Complex rooflines, bays, mixed materials | 15% or more | Have your installer confirm the final count |
Worked Example: A 40 x 30 House
Say your house is 40 feet long by 30 feet wide with 9-foot walls, two gable ends (30-foot base, 6-foot rise), 3 doors, and 10 windows:
- Walls: 2 x (40 x 9) + 2 x (30 x 9) = 1,260 sq ft
- Gables: 2 x (30 x 6 / 2) = 180 sq ft
- Openings: 3 x 20 + 10 x 15 = 210 sq ft
- Net: 1,260 + 180 – 210 = 1,230 sq ft
- Add 10% waste: 1,230 x 1.10 = 1,353, divided by 100 and rounded up = 14 squares
- Cartons: 14 / 2 = 7 cartons of vinyl
At $250 per square for mid-grade vinyl, the material runs about $3,500 before trim, house wrap, and fasteners. Try the same numbers in the calculator above and you will get the same answer.
6 Common Siding Measuring Mistakes
- Forgetting the gables. Two gables on the example house add 180 square feet, nearly two full squares. They are the most commonly skipped area.
- Measuring the roof instead of the wall. Wall height stops at the eaves. The sloped roof surface above it is not wall area.
- Skipping the openings. Ten windows and three doors remove 210 square feet here, over two squares of material you would otherwise overbuy.
- Buying the exact square count. One bad plank or one miscut gable angle and the job stalls. The waste allowance is what keeps a weekend project on schedule.
- Assuming every carton covers 200 sq ft. Most do, but profiles vary from 100 to 200. Read the label on your actual product before finalizing the order.
- Pricing material as the total job. Panels are only part of it. Trim, J-channel, corner posts, house wrap, and labor often rival the siding cost itself.
2026 Siding Cost Guide
These are typical US material-only ranges per square, not quotes and not installed prices. Region, brand, and profile move the numbers.
- Vinyl: $100 to $300 per square for panels. Big-box stores typically price panels at $1.50 to $4.00 per square foot, which works out to $150 to $400 per square.
- Fiber cement: $200 to $500 per square. Premium brands such as James Hardie sit at the higher end.
- Wood (cedar): $300 to $600 per square. The prettiest and the thirstiest for maintenance.
- Engineered wood: $250 to $450 per square. A middle path between vinyl cost and fiber cement durability.
- Installed prices run much higher: vinyl typically $350 to $700 per square installed, fiber cement $600 to $1,200, because labor, trim, and old siding removal add up fast.
- Trim and accessories: budget extra for J-channel, corner posts, starter strip, soffit, and house wrap. They are priced separately from the panels and surprise first-time buyers.
Siding Calculator FAQs
Add up each wall’s length times its height, add the gable triangles (base times height divided by 2), subtract 20 square feet per door and 15 per window, then divide by 100 to convert to squares and add 10 percent for waste. The calculator above runs this exact sequence.
A square is the standard trade unit for siding: 100 square feet of finished wall coverage. Manufacturers such as CertainTeed and James Hardie price and estimate in squares, contractors quote in squares, and suppliers stock in squares. If your net wall area is 1,400 square feet, that is 14 squares before waste.
Careful: house square footage is floor space, not wall area. A 2,000 square foot two-story home can easily have 2,000 to 2,500 square feet of wall area once you count both stories and the gables. Measure the walls themselves; as a rough rule of thumb, wall area often lands near or above the home’s floor square footage for two-story houses.
Measure the base (the width of the wall at the eaves) and the vertical rise from the eaves line to the peak, then multiply base times height and divide by 2. A 30-foot base with a 6-foot rise is 90 square feet per gable. Gables waste more material than flat walls because every course needs an angled cut, so they also justify the higher end of the waste range.
Panels alone typically run $100 to $300 per square in 2026, with big-box pricing of $1.50 to $4.00 per square foot working out to $150 to $400 per square. Installed, vinyl usually lands at $350 to $700 per square once labor, trim, and accessories are included. Thicker and insulated panels sit at the higher end.
Divide your squares by the coverage per box and round up. A standard vinyl carton covers about 200 square feet, which is 2 squares, so 14 squares means 7 cartons. Check your product’s label first, since some profiles pack only 100 square feet per carton. Fiber cement and wood do not come in 200-square-foot cartons; they are sold by the plank or bundle.
Yes, always. This calculator removes 20 square feet per door and 15 per window. For oversized openings such as sliding glass doors or double garage doors, measure the actual dimensions instead of using the defaults, since one garage door can exceed 110 square feet on its own.
Ten percent is the standard allowance for a simple rectangular house, covering offcuts, bad pieces, and mis-cuts. Move to 12 to 15 percent for houses with gables, bump-outs, and many corners, where angled cuts waste more. Buy the extra in the same dye lot as the main order so the color matches.
It depends on the wall measurements, not the floor plan. A 1,500 square foot ranch with 8-foot walls might have around 1,200 to 1,400 square feet of wall area, which works out to 13 to 16 squares with waste. A two-story 1,500 square foot home can need 18 to 22 squares. Measure the walls; the floor square footage alone cannot give you the answer.
Fiber cement costs more. Vinyl panels run $100 to $300 per square for material while fiber cement runs $200 to $500, and installed the gap widens further: roughly $350 to $700 per square for vinyl versus $600 to $1,200 for fiber cement. Vinyl wins on price and maintenance; fiber cement wins on fire resistance and a wood-like look.