Siding Calculator
Measure wall rectangles and triangular gables, subtract suitable openings, then convert the adjusted cladding area into squares and full cartons.
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View all saved project estimatesWhat does the siding calculator calculate?
Siding quantity equals rectangular wall area plus gable area minus doors and windows, increased for cuts and layout waste. One siding square covers 100 square feet. Enter the exact carton coverage to receive full-box quantity, while corners, starter, trim, flashing, and housewrap remain separate.
Siding area, square, and carton formula
Rectangular elevations and gables form gross area. Openings reduce field coverage, allowance covers cuts, and the result converts to 100-square-foot squares and product-specific cartons.
How to measure for an accurate estimate
- Measure each exterior elevation and group wall rectangles only when their height is identical.
- Calculate each triangular gable as base times vertical gable height divided by two, then add them.
- Measure doors, windows, and large un-clad areas instead of relying on standard opening sizes.
- Use the field coverage printed for the exact siding carton, excluding accessory pieces.
Siding a four-wall home
Walls total 160 feet by 9 feet, gables add 240 square feet, openings remove 260, cartons cover 200, and waste is 10%.
Net area is 1,420 square feet; 1,562 square feet with allowance equals 15.62 squares and requires 8 cartons.Before you purchase material
- Use an allowance suited to short walls, many openings, gables, color selection, and reusable offcuts.
- Order matching field panels, corners, starter, channels, trim, flashing, and fasteners as a complete system.
- Confirm wall preparation, drainage plane, clearances, attachment, and expansion requirements before installation.
- Have hazardous-material and moisture conditions assessed before disturbing existing exterior layers.
Common questions
What is a square of siding?
One siding square is 100 square feet of installed field coverage. It is a quantity unit, not the number of panels or cartons. Package coverage varies by profile and product, so use the label to convert squares to cartons.
Should windows and doors be subtracted from siding?
Subtract measured openings for field siding, but keep an adequate cutting allowance because panels around openings create offcuts. Small openings may not reduce purchases by a full carton. Window flashing, trim, and channels are calculated separately.
How do I calculate siding for a gable?
Treat a simple triangular gable as one-half times its horizontal base times its vertical height above the rectangular wall. Measure more complex gables as smaller triangles and rectangles, then add their areas before subtracting openings.
Does siding square footage include trim?
No. Field siding area does not provide corner posts, starter strips, J-channel, window and door trim, frieze, soffit, fascia, flashing, or water-resistive barrier quantities. Build those linear and assembly-specific takeoffs from each elevation.
Sources and reference standards
- Vinyl Siding InstituteManufacturer-industry installation resources for vinyl siding and related accessories.
See every citation and the calculators that use it in the calculator source index.
Use this result in a complete project plan
Exterior envelope planner
Siding, windows, exterior coatings and gutters meet at the same openings, flashings, roof edges and drainage paths. Pricing them independently without a coordinated elevation can duplicate access and trim work, omit water-management details or sequence new finishes before concealed damage is resolved. This guide turns the exterior into measured elevations, interface details and comparable local quote packages.
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