Siding Calculator

Estimate net siding area, 100-sq-ft squares and panels at fixed 8-sq-ft exposure, deducting measured openings and adding entered waste. Calculate it clearly with Figur.

Deduct wall openings before estimating siding squares

Gross wall area = total wall length × average height in feet. Subtract the entered door and window area, then multiply net area by (1 + waste ÷ 100). Squares = order area ÷ 100, displayed to one decimal, not rounded up to whole squares. Panels = round up(order area ÷ 8) using fixed 8 sq ft exposed coverage. Openings equal to or larger than gross area produce a validation message, not a takeoff.

Method and assumptions

Net area = wall length × height − openings area. Order area = net area × (1 + waste ÷ 100). Squares = order area ÷ 100; panels = round up(order area ÷ 8).

  • Length and average height represent the measured wall area; gables and irregular sections need separate measurement.
  • Opening area is entered in square feet, not as a count. Net area must be positive.
  • Panel exposure is fixed at 8 sq ft, such as 12 ft × 8 inches. The tool does not accept another panel coverage or optimize carton sizes.
  • Only entered waste is added. Starter strips, corner pieces, trim, soffit, housewrap, fasteners and labor are excluded.

Planning takeoff, not a binding bid, structural design or engineering advice. Confirm field measurements, product coverage, installation requirements and supplier quantities before buying.

Sources and references

The result uses your inputs and the tool's documented assumptions; it does not fetch current prices, rates or products.

Worked example

Walls total 120 ft long and 9 ft high, with 180 sq ft of openings and 10% waste.

120 × 9 = 1,080 sq ft gross; − 180 = 900 sq ft net. 900 × 1.10 = 990 sq ft to order; 990 ÷ 100 = 9.9 squares. Round up 990 ÷ 8 = 123.75 to 124 panels.

Frequently asked questions

Are siding squares rounded up?

No. They are displayed to one decimal. Panels round up separately using the unrounded order area, so do not calculate them from the displayed squares.

Can I change panel coverage?

Not in this calculator. It uses 8 sq ft of exposed coverage per panel. Verify your product and adjust a separate takeoff if it differs.

What if openings cover the whole wall area?

The calculator rejects a zero or negative net area. Check your opening measurements and wall dimensions.

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