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Roofing Calculator

From footprint and pitch to squares and bundles.

Roofing is sold in squares (100 sq ft), but your house is measured in footprint and pitch. This calculator applies the correct slope multiplier for your roof pitch, adds the right waste factor for gable versus hip roofs, and converts the result into bundles, felt rolls, and nails — the numbers a supplier actually quotes in.

Why people use this

Homeowners use this before calling roofers: knowing your square count and bundle math converts a black-box quote into a conversation. Handy homeowners pricing a shed or garage roof get the full materials list without climbing a ladder twice.

How it works

1. Enter the roof footprint length and width (the building outline, not the slope surface).
2. Pick the pitch — rise per 12 inches of run. A 6/12 roof multiplies area by 1.118.
3. Choose gable (10% waste) or hip/complex (15% waste).
4. Read squares, bundles (3 per square), underlayment rolls, and nails; open the cost section for a project estimate.

Common questions

How many bundles of shingles are in a square?

Three bundles cover one square (100 sq ft) for standard architectural shingles. Some heavyweight designer shingles run 4 bundles per square — check the wrapper before ordering.

Why is my roofer's square count higher than this estimate?

This calculator covers field shingles, underlayment, and nails. Roofers also charge for tear-off and disposal, ridge cap, drip edge, flashing, pipe boots, and steep-slope or story surcharges. Use this number to sanity-check the materials line of their quote, not the total.

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