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Roofing Materials Calculator

Estimate roof covering quantities and material allowance.

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Calculator inputs

Roofing material details

Ready to calculate

Roof size

Use a building footprint plus pitch, or enter a measured roof-surface area directly. This is a material estimate, not a structural roof design tool.

Measurement methodBuilding lengthBuilding widthPitch rise per 12Project units

Shingles & allowance

A roofing square is 100 ft². Many standard asphalt shingles use about 3 bundles per square, but the product wrapper should always override this starting value.

Waste allowance

Bundles per roofing squareUnderlayment coverage per roll (m²)

Optional cost estimate

Add the price per shingle bundle for a material-only estimate. Accessories, labor, delivery and taxes are not included.

CurrencyPrice per shingle bundle

Verify field measurements, overhangs, valleys, manufacturer coverage and local roofing requirements before ordering.

Your estimate

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Ready when you are

Estimate roofing squares, shingle bundles, underlayment rolls and optional material cost.

Plan with confidence

How to use the Roofing Materials Calculator

Estimate roofing coverage from a measured roof area or from a rectangular footprint plus roof pitch, then convert it into practical purchase quantities.

Step by step

What to enter

Choose whether you know the measured roof area or want to calculate it from footprint and pitch.
Enter the roof dimensions and pitch or slope.
Set your waste allowance, bundles per roofing square and underlayment-roll coverage.
Optionally enter material prices to estimate the purchase cost.

Method

How the calculation works

For footprint mode, PlanCalq applies a slope factor to the horizontal footprint to estimate actual roof surface area. If you already know the measured roof area, that value is used directly.

Waste is added before the total is converted to roofing squares, bundles and underlayment rolls. All purchase quantities are rounded up.

Calculation summaryRoof footprint × slope factor = estimated roof surface areaRoof area × (1 + waste %) = recommended coverageRecommended coverage ÷ coverage per purchase unit = units to buy (rounded up)

Common questions