Siding Calculator
Calculate siding square footage for walls and gables, subtract windows and doors, add waste, and estimate siding squares or coverage-based pieces.
Enter measurements below. The result updates as you type.
Calculation breakdown
Wall area
Rectangles use width x height.
Gable area
Triangular gables use base x height / 2.
Net area
288 - 15 = 273 sq ft
Purchase area
273 sq ft plus 10% waste, then divided by coverage.
Advertisement
More Siding help
Related calculators and guides
Open the project hub for nearby tools, measurement guidance, and published articles.
Formula explanation
Core siding estimate basis
Net siding area = wall area + gable area - openings
- Product coverage should be user-selected or entered.
- Final quantities must round according to the selected material unit.
- Trim, starter strips, corners, labor, and installed cost are not included in the calculated siding quantity.
Worked example
Simple wall example
24 ft wide x 9 ft high wall, before openings
- 1Multiply width by height.
- 2Subtract supported doors and windows.
- 3Divide by product coverage after waste is added.
Gross wall area: 216 square feet, before deductions and waste.
Estimate assumptions
Check these assumptions before ordering
- Main walls, gables, and openings should be calculated as separate sections.
- Coverage depends on the selected siding product and exposure.
- Trim, starter strips, corners, and specialty pieces are outside this calculator unless entered as separate coverage needs.
Measurement checklist
How to measure
- Measure each rectangular wall section by width and height.
- Measure triangular gables by base width and vertical height.
- Measure windows and doors as opening width times height so they can be deducted.
- Use the panel, carton, or piece coverage supplied by the material you plan to buy.
Avoid these errors
Common mistakes
- Forgetting that triangular gables use half of base times height.
- Deducting openings larger than the gross wall area.
- Confusing siding squares with square feet; one square is 100 square feet.
- Using panel count without checking exposure, trim, starter, and corner requirements.
Estimate disclaimer
Verify before ordering.
Use the output as a planning baseline. Site conditions, product coverage, waste, supplier units, installation method, and local requirements can change the final quantity.
Related calculators
Continue the same project estimate
Exterior Projects
Gable Siding Calculator
Calculate triangular gable siding area, subtract gable openings, and convert the result into siding squares or packages.
Exterior Projects
Siding Square Calculator
Enter known siding area or one simple wall, subtract openings, and convert the result into siding squares and packages.
Exterior Projects
Vinyl Siding Calculator
Estimate vinyl siding panels and cartons from a single wall or known area. Use the actual installed panel exposure, waste allowance, and carton count.
Exterior Materials
Stone Veneer Calculator
Plan manufactured or thin-stone veneer quantities with editable product coverage.
Published guides
Understand the measurements and assumptions
Supporting guide
How Much Siding Do I Need?
Add wall and gable areas, subtract openings, convert to siding squares or product coverage units, and apply a clear waste allowance.
Read guide
Supporting guide
Vinyl Siding Cost by House Size: Area, Squares, and Scope
Learn why house floor area is not siding area, then estimate vinyl siding cost from measured walls, siding squares, product coverage, and project scope.
Read guide
Common questions
Use the result with context
01Can I include triangular gables when calculating siding square footage?+
Yes. Add gable sections with base and height; the calculator uses base times height divided by two.
02Can siding coverage vary?+
Yes. Coverage is editable because profile, exposure, package size, and manufacturer data can vary.
03How many square feet are in one square of siding?+
One siding square covers 100 square feet. For example, 850 square feet of purchase area equals 8.5 siding squares; the calculator shows the square-footage and siding-square results after waste.
04Should I deduct windows and doors when measuring siding?+
Yes. Add the measured width and height of windows and doors to the openings section. The calculator deducts their area before applying waste; allow separately for trim and cut complexity.