Siding Calculator
Estimate siding in squares and pieces from wall area, openings and panel exposure.
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What this tool does
Estimate siding in squares and pieces from wall area, openings and panel exposure. A 'square' of siding is 100 sq ft of coverage. Exposure is the visible height of each course (e.g. 5 in for double-5 vinyl), not the full panel height.
How to use the Siding Calculator
- Enter or select total wall length (all walls) in ft.
- Enter or select height in ft.
- Enter or select doors and windows area in sqft.
- Enter or select panel exposure in in.
- Enter or select panel length in ft.
- Enter or select waste allowance (%).
- Read the calculated result; change any measurement to compare alternatives.
Formula
net area = wallLength × height − openings; squares = net area × (1 + waste/100) / 100; pieces = ceil(net area with waste / (panelLength × exposure/12))
- wallLength
- Total wall length (all walls) (ft, before metric conversion)
- height
- Height (ft, before metric conversion)
- openings
- Doors and windows area (sqft, before metric conversion)
- exposure
- Panel exposure (in, before metric conversion)
- panelLength
- Panel length (ft, before metric conversion)
- waste
- Waste allowance (%)
A 'square' of siding is 100 sq ft of coverage. Exposure is the visible height of each course (e.g. 5 in for double-5 vinyl), not the full panel height.
Worked example
For siding calculator, the following measurements illustrate the exact method: Total wall length (all walls): 120; Height: 8; Doors and windows area: 180; Panel exposure: 5; Panel length: 12.5; Waste allowance (%): 10.
Inputs
- Total wall length (all walls)120 ft
- Height8 ft
- Doors and windows area180 sq ft
- Panel exposure5 in
- Panel length12.5 ft
- Waste allowance (%)10
Result
- Siding squares8.58
- Panels / pieces165
- Net wall area780 sq ft
- Coverage per piece5.21 sq ft
Results explained
- Siding squares
- Siding squares from the formula above. A 'square' of siding is 100 sq ft of coverage. Exposure is the visible height of each course (e.g. 5 in for double-5 vinyl), not the full panel height.
- Panels / pieces
- Panels / pieces from the formula above. A 'square' of siding is 100 sq ft of coverage. Exposure is the visible height of each course (e.g. 5 in for double-5 vinyl), not the full panel height.
- Net wall area
- Net wall area from the formula above, expressed in sqft before metric conversion. A 'square' of siding is 100 sq ft of coverage. Exposure is the visible height of each course (e.g. 5 in for double-5 vinyl), not the full panel height.
- Coverage per piece
- Coverage per piece from the formula above, expressed in sqft before metric conversion. A 'square' of siding is 100 sq ft of coverage. Exposure is the visible height of each course (e.g. 5 in for double-5 vinyl), not the full panel height.
Frequently asked questions
Multiply total wall length by wall height, subtract doors and windows, then divide by 100 for squares. A 120 ft perimeter × 8 ft tall minus 180 sq ft of openings is 780 sq ft ≈ 8.6 squares with waste.
100 square feet of finished wall coverage — the unit siding is priced and sold by, regardless of material.
The visible course height once panels overlap: double-4 vinyl exposes 8 in per panel (two 4 in courses), double-5 exposes 10 in. Enter the per-course exposure (4 or 5 in) with the full panel length.
Yes for large openings — but keep the waste allowance, because cuts around openings consume much of what you subtracted.
No — those are linear-foot accessories ordered separately: starter strip and J-channel roughly equal the wall perimeter plus opening perimeters.