Siding Calculator
Estimate how much siding to buy. A 40 x 30 ft house with 9 ft walls and two gables needs about 14.19 squares of siding.
How to measure for siding
Add up the wall area (perimeter x height) and the two triangular gables (0.5 x width x gable height each), then subtract windows and doors. Add 10% for waste and cuts and divide by 100 to get squares.
This house has 1,260 sq ft of walls and 180 sq ft of gables. After 150 sq ft of openings the net is 1,290 sq ft, which is 14.19 squares with waste. At $300 per square the siding costs about $4,257.00.
What else to order
- Corner posts, J-channel, starter strip and trim
- Housewrap and fasteners
- Soffit and fascia if replacing them
Labor generally doubles the material cost. Vinyl is the cheapest, fiber cement mid range and wood or metal the highest. Measuring the roof too? Use the roofing calculator.
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Frequently asked questions
How many squares of siding do I need?
Divide the net wall area plus waste by 100. A 1,500 sq ft wall area needs about 16.5 squares at 10% waste.
How much does siding cost per square?
Vinyl is $100 to $300 per square for material, fiber cement $250 to $500.
Do I include gables?
Yes. Gables are triangles. Area is half the base times the height.
How much waste should I allow?
10% on simple houses, 15% with many corners or windows.
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