Siding Calculator — How Much Siding Do I Need?
Estimate the exterior siding required for a house by entering the building dimensions, number of gable ends, doors and window area, and a waste factor. Get the result in squares (1 square = 100 ft²) for ordering from your supplier.
Unit system
ft
ft
ft
ft
ft²
%
1 square = 100 ft² of siding coverage (with waste allowance)
15.7 sq
Siding needed- 1
Peiriméadar
2 × (40 + 30) ft = 140 - 2
Wall area
140 × 10 ft = 1,400 ft² - 3
Gable area
2 × ½ × 30 × 5 ft = 150 ft² - 4
Net area (minus openings)
1,550 − 120 ft² = 1,430 ft² - 5
Squares of siding
1,430 ft² × 1.1 ÷ 100 = 15.7Waste factor = 1 + waste%/100; divide by 100 because 1 square = 100 ft².
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Total siding = (2 × (L + W) × wall height + gable triangles − openings) × (1 + waste%), divided by 100 to get squares. For a 40 × 30 ft house, 10 ft walls, 2 gables of 5 ft rise, and 120 ft² of openings with 10% waste, you need about 17 squares. Add price per square for a material cost estimate.
Foirmle
How this is calculated
The calculator adds up the gross exterior wall area as 2 × (length + width) × eave height, then adds the triangular gable area for each gable end as ½ × width × gable rise. Window and door openings are subtracted from the gross area — enter the combined area of all openings (a typical 3×6 ft door is 18 ft², a 3×4 ft window is 12 ft²).
The net area is converted to "squares" — the industry-standard unit where 1 square equals 100 square feet of coverage. A waste allowance of 5–10% is typical for straight walls with minimal cuts; use 10–15% for hipped rooflines, many corners, or complex patterns. Always order slightly more than the calculation, since short off-cuts cannot usually be returned.
Siding comes in many styles — vinyl lap siding, fibre cement, wood boards, board and batten — each with its own coverage per plank. Manufacturers list square footage of coverage per panel; divide your required area (in square feet) by that coverage figure to get panel count. If you know the price per square (common for vinyl), enter it to get an estimated material cost. Labour, fasteners, trim, and flashing are not included.
Ceisteanna coitianta
In the North American siding trade, one square equals 100 square feet of wall coverage. Suppliers sell siding by the square (or fraction thereof), making it easy to compare costs. Divide your required square footage by 100 to get the number of squares to order.
A 10% waste allowance is a common starting point for a simple rectangular house. Add 15% for homes with many corners, diagonal cuts, dormers or complex trim. If you are working with a natural wood product that requires matching grain or colour, up to 20% may be warranted.
No — soffit (the underside of the eave overhang) and fascia (the board along the eave edge) are typically sold as separate materials and are not counted in wall siding squares. Calculate them separately if needed.
Ar a dtugtar freisin
TG we-Calculate Editorial Team. (2026). Siding Calculator — How Much Siding Do I Need? [Online calculator]. TG we-Calculate. https://we-calculate.com/ga/calculator/siding-calculator
TG we-Calculate Editorial Team. "Siding Calculator — How Much Siding Do I Need?." TG we-Calculate. 2026. https://we-calculate.com/ga/calculator/siding-calculator.
TG we-Calculate Editorial Team, "Siding Calculator — How Much Siding Do I Need?," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/ga/calculator/siding-calculator
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