Siding Calculator
Estimate exterior siding area, squares, cartons, starter trim, corner trim and material cost after opening deductions.
Default project preview
13.42 squares
Net wall area
1,220 ft²
Cartons
7
Starter strip
140 ft
Corner trim
36 ft
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Building length
Enter this project assumption in ft. The current imperial default is 40 ft.
Building width
Enter this project assumption in ft. The current imperial default is 30 ft.
Wall height
Enter this project assumption in ft. The current imperial default is 9 ft.
Total gable area
Enter this project assumption in ft². The current imperial default is 180 ft². Minimum: 0.
Doors and windows
Enter this project assumption in ft². The current imperial default is 220 ft². Minimum: 0.
Waste allowance
Enter this project assumption in %. The current imperial default is 10 %. Minimum: 0. Maximum: 50.
Coverage per carton
Enter this project assumption in ft². The current imperial default is 200 ft².
Price per carton
Enter this project assumption in a unitless value. The current imperial default is 240. Minimum: 0.
Trim price per length unit
Enter this project assumption in per ft. The current imperial default is 2.5 per ft. Minimum: 0.
How to read the outputs
Net wall area
after openings. Default preview: 1,220 ft².
Cartons
200 ft² each. Default preview: 7.
Starter strip
building perimeter. Default preview: 140 ft.
Corner trim
four outside corners. Default preview: 36 ft.
Siding cost
full cartons. Default preview: $1,680.00.
Total material cost
siding and estimated trim. Default preview: $2,120.00.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Net wall area = perimeter × wall height + gables − openings. Order area = net area × waste factor. Cartons = round up (order area ÷ carton coverage).
Reviewed project guidance
How to use this estimate in a real project
Last reviewed: July 29, 2026
Use this calculator to estimate siding coverage, panels or cartons from net wall area, product exposure and waste. Weather-resistive barriers, flashing, fastening and clearances require product-specific planning.
Calculation steps
- 1Measure each wall area.
- 2Subtract windows, doors and other excluded openings.
- 3Add gables and special shapes.
- 4Apply layout allowance and round to product packages.
Worked numerical example
A house with 2,200 ft² gross wall area and 280 ft² of openings has 1,920 ft² net. With 12% waste, order 2,150.4 ft², rounded to full cartons or panels.
Purchasing and rounding
Use installed coverage, not nominal panel dimensions. Starter strips, corners, trim and flashing are separate accessories.
Interpret the result
Waste depends on wall segmentation, panel length and opening density. A simple rectangle often needs less than a house with many short runs.
Page-specific assumptions
- One siding product and exposure.
- Net openings are measured accurately.
- Accessories are estimated separately.
- Allowance reflects cut layout.
Common mistakes
- Using floor area.
- Ignoring gables.
- Using nominal board width instead of exposure.
- Omitting corners and starter accessories.
Primary and technical references
BuildMeter provides planning estimates, not engineering, architectural, electrical, mechanical, plumbing, permit or code approval. Review the methodology and verify final decisions with product documentation and qualified professionals.
BuildMeter Guides
Understand the measurements and assumptions
Use these visible reference guides before changing project inputs or planning allowances.
FAQ
Siding Calculator questions
What is one siding square?+
In imperial measurements, one siding square covers 100 square feet.
Should gables be measured separately?+
Yes. Add the combined triangular or irregular gable area to the rectangular wall area.
Does this include all trim accessories?+
No. It estimates starter and outside corners only; product-specific channels and flashing require a detailed takeoff.