Siding Material Calculator

Estimate siding coverage, whole packages and entered material cost from measured wall/gable areas, openings, waste and package coverage.

Interactive calculator · Method SIDING-1.1 · Last reviewed: 2026-10-05

Calculate your scenario

Rectangular wall area = width × height; triangular gable area = base × height/2. Gross area = entered wall area + entered gable area. Net coverage = gross − excluded openings. Ordering coverage = net × (1 + waste/100). Whole packages = ceiling(ordering coverage/installed coverage per package). Material cost = whole packages × entered package price.

Your inputs

Try an example

Measured rectangular wall area (sq ft)

Measured triangular/gable area (sq ft)

Openings to exclude (sq ft)

Ordering allowance (%)

Installed coverage per package (sq ft/package)

Entered package price (USD/package)

Default worked example. Edit the inputs to calculate your scenario.

Default worked example

Whole siding packages 11

Ordering coverage after allowance 1,045 sq ft

Net wall coverage 950 sq ft

Gross measured area 1,100 sq ft

Entered material cost $1,650.00

1,100 gross sq ft − 150 openings = 950 net sq ft. The entered allowance gives 1,045 sq ft; round up to 11 packages at entered coverage.

How to use the calculator

Enter measured rectangular wall area, gable area and openings in square feet. Enter waste, installed coverage per whole package and your package price. Check net area before the whole-package order.

What the result means

Walls of 1,000 sq ft plus 100 sq ft of gables minus 150 sq ft of openings leave 950 sq ft. A 10% allowance gives 1,045 sq ft, or 11 packages at 100 sq ft installed coverage each.

Formula and units

Rectangular wall area = width × height; triangular gable area = base × height/2. Gross area = entered wall area + entered gable area. Net coverage = gross − excluded openings. Ordering coverage = net × (1 + waste/100). Whole packages = ceiling(ordering coverage/installed coverage per package), using decimal input arithmetic before whole-unit rounding. Display rounding never changes the package count. Material cost = whole packages × entered package price.

Worked examples

Large wall area with 150 sq ft openings: Measured rectangular wall area: 1000 sq ft; Measured triangular/gable area: 100 sq ft; Openings to exclude: 150 sq ft; Ordering allowance: 10 %; Installed coverage per package: 100 sq ft/package; Entered package price: 150 USD/package.
Example result: Whole siding packages: 11; Ordering coverage after allowance: 1,045 sq ft; Net wall coverage: 950 sq ft; Gross measured area: 1,100 sq ft; Entered material cost: $1,650.00.

Small project using 80 sq ft packages: Measured rectangular wall area: 400 sq ft; Measured triangular/gable area: 40 sq ft; Openings to exclude: 40 sq ft; Ordering allowance: 5 %; Installed coverage per package: 80 sq ft/package; Entered package price: 120 USD/package.
Example result: Whole siding packages: 6; Ordering coverage after allowance: 420 sq ft; Net wall coverage: 400 sq ft; Gross measured area: 440 sq ft; Entered material cost: $720.00.

Limitations and common mistakes

Measure each wall and gable separately and add like units before entering totals. Manufacturer overlap and installed coverage vary; use the package specification. Waste is an entered allowance, not a universal rate. Trim, corners, starter strips, fasteners, flashing, labor and taxes are excluded. This does not design fastening or assess wind/structural loads.

Use installed coverage from the selected package, not nominal board dimensions. Openings are subtracted before waste; do not subtract them again from the order.

Sources and assumptions

Method SIDING-1.1; last formula review 2026-10-05. Sources and their supported claims. Calculation methodology.