Wall area · siding squares · installed coverage
Siding Calculator
Estimate siding from wall faces and gables, with your selected opening deductions and waste allowance. See siding squares and whole packages, or estimate lap planks using installed exposure, with optional material cost.
Worked example
- Net wall area
- 900 sq ft
- With 10% allowance
- 990 sq ft / 9.9 squares
- 200 sq ft per package
- 1,000 sq ft purchased
Illustrative example. Measurements, allowances, product details, and prices are not prefilled from this example.
Your result
Know the area before you shop
Enter your dimensions to see net square footage, metric conversions, and a section-by-section breakdown here.
Suggest an improvement
Choose and measure
Choose package coverage or lap-plank exposure
For vinyl siding or any product sold by the package, select packages and enter the manufacturer’s installed coverage per box or bundle. A siding square is 100 sq ft of installed area; it is not a fixed number of boxes.
For lap siding, including suitable fiber cement products, select lap planks and enter usable plank length and visible exposure after overlap. The full board width is not installed coverage. Material or brand names alone do not determine yield; use your product specifications.
The estimate covers siding packages or planks and their entered material prices, not a complete installation. Use the Linear Foot Calculator to total measured runs for starter strips, corners, and other trim separately; accessory layouts and installation requirements still come from the manufacturer.
Measure first
Use wall faces and installed product coverage.
Add rectangular walls and triangular gables, not the building’s floor area. Opening deductions depend on your supplier’s takeoff method: add excluded areas only when that method calls for them. Enter installed coverage per package, or usable lap plank length and visible exposure after overlap.
Selected net wall area
Add included wall and gable areas, subtract the excluded sections you choose, then apply the extra allowance once.
Siding squares
One siding square is 100 sq ft. Net squares = net area ÷ 100; planning squares use area after the allowance. A square is not a package.
Packages or lap planks
Whole packages = planning area ÷ installed package coverage, rounded up. For lap planks, coverage = length (ft) × exposure (in) ÷ 12; round up the resulting area-based plank estimate.
Purchase cost
Whole estimated purchase units × the entered price per package or plank. Installed exposure replaces full face width so overlap is not counted as coverage.
From measurement to purchase
A 1,000 sq ft wall area minus 100 sq ft of selected deductions gives 900 sq ft. At 10% extra, plan 990 sq ft or 9.9 siding squares. A 200 sq ft package needs five whole packages covering 1,000 sq ft, with 10 sq ft from package rounding. At an illustrative $250/package, material cost is $1,250. Alternatively, a 12 ft lap plank at 7 in exposure covers 7 sq ft, so the area-based estimate is 142 planks; course and cut layout may require more.
FAQ
Siding planning questions
How much is one square of siding?
One square equals 100 sq ft of installed wall coverage. Package coverage varies by product, so enter its label rather than assuming every box contains one or two squares.
Should I deduct every door and window?
Not automatically. Manufacturer estimating methods differ; some retain small openings as a waste allowance. Use excluded sections according to your product and supplier’s method, and avoid deducting the same area twice.
What does installed exposure mean?
For lap siding it is the visible height of each course after overlap, not the full plank width. Coverage per plank is usable length × exposure in consistent units.
Does the tool create a course-by-course cutting plan?
No. Package and plank quantities are based on area and your allowance. Seams, end laps, stagger, opening cuts and offcut reuse are not laid out, and actual requirements can be higher.
Does the cost include a complete siding installation?
No. It covers only the entered package or plank price. Starter strips, corner posts, J-channel, soffit, fixings, labor, delivery and tax are excluded.
References
Check product specifications before ordering.
James Hardie: HardiePlank coverage and estimating
Manufacturer coverage chart uses wall area, exposure and 100 sq ft siding squares.
View reference ↗Gentek: aluminum siding installation guide
Manufacturer estimating method discusses how openings are treated.
View reference ↗