Exterior calculator

Siding Calculator

Estimate siding cartons from walls, gables, openings, and package coverage. Switch between US customary and metric units, adjust the assumptions, and keep every step visible.

01 Measure02 Allow03 Order

Project inputs

Use one unit system throughout. Defaults show a realistic example; replace them with measurements from your project.

Unit system

Rectangular wall areaPlanning default — verify the selected product or project specification.ft²Total gable basePlanning default — verify the selected product or project specification.ftAverage gable heightPlanning default — verify the selected product or project specification.ftOpenings deductedExample input — replace with your project value.ft²Coverage per cartonPlanning default — verify the selected product or project specification.ft²Waste allowanceEditable planning allowance for cuts, breakage, compaction, or site loss.%Price per cartonOptional local price; enter zero to hide the cost estimate.currencyCurrencyPlanning default — verify the selected product or project specification.

Measurement guideMeasure the full run and height; subtract gates or openings where requested.

Measure the finished shape. Measure each elevation and confirm corners, starter, trim, laps, and carton coverage for the selected siding system.

Estimate matches the inputs shown.

ReviewedNovember 2, 2026

ByBuildGauge Editorial Team

ScopeFormula, defaults & sources

Report an issue ↗

The calculation

A visible formula, not a black box.

Area & cartons · Mathematical derivationcartons = (wall area + gable base × height ÷ 2 − openings) × waste factor ÷ carton coverage

Inputs are converted to a common base unit before calculation. Purchase quantities are rounded only at the final buying boundary.

Example inputDefaultStatus

Rectangular wall area1800 ft²Planning default — verify

Total gable base40 ftPlanning default — verify

Average gable height6 ftPlanning default — verify

Openings deducted240 ft²Planning default — verify

Coverage per carton200 ft²Planning default — verify

Waste allowance10 %Planning default — verify

Price per carton180 currencyPlanning default — verify

CurrencyUSD Planning default — verify

Worked example

Example: planning siding

Using the editable example inputs—rectangular wall area 1800 ft², total gable base 40 ft, average gable height 6 ft—the calculator returns 10 cartons. Replace every example with measured dimensions and the selected product label before purchase.

Use this to understand the workflow—not as a recommendation for your project.

Sources & scope

What supports this calculation.

Industry guidanceCertainTeed siding estimating guide ↗

Supports the product rule or estimating basis used by the Siding Calculator; geometry and unit conversion remain visibly derived in the calculator.

Mathematical derivationNIST SI conversion factors ↗

Exact length, area, and volume unit conversions; the project formula is derived from standard geometry.

Common mistakes

Check the job, not just the number.

01Leaving the example siding inputs unchanged instead of entering measured project values.
02Treating an editable coverage, size, density, or allowance as universal instead of checking the selected product label, project documents, and local requirements.
03Ordering from the rounded result without reviewing exclusions: Measure each elevation and confirm corners, starter, trim, laps, and carton coverage for the selected siding system.

Questions, answered

Siding FAQ

What does the Siding Calculator estimate?

Estimate siding cartons from walls, gables, openings, and package coverage. The primary output is area & cartons, with the intermediate assumptions kept visible.

How is the siding result calculated?

The visible formula is: cartons = (wall area + gable base × height ÷ 2 − openings) × waste factor ÷ carton coverage. Inputs are converted to a common base unit before the final purchase boundary is rounded.

Are the default values recommendations?

No. Dimensions are worked examples and product-dependent presets are planning defaults. Replace them with the selected product label, project documents, and local requirements.

Is the result ready to order from?

Use it as a checked planning estimate, then confirm packaging, minimum orders, installation instructions, site conditions, and any code or professional-design requirements.