Roofing Calculator
How many shingles do you need? Enter your roof size and pitch.
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Roof area—
Roofing squares—
Estimated cost—
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How this calculator works
It takes your roof’s footprint, multiplies by a pitch factor to get the true sloped area, converts to roofing “squares” (100 sq ft each), then to shingle bundles at 3 bundles per square plus 10% waste.
Worked example — a 40 ft × 30 ft footprint, 6/12 pitch:
1,200 × 1.12 = 1,344 sq ft → 13.4 squares → 45 bundles with waste.
Measure footprint, not slope
Enter the building’s footprint (length × width as seen from above). The pitch factor converts it to the larger sloped surface area for you.
Frequently asked questions
How many bundles of shingles in a square?
3 bundles cover one roofing square (100 sq ft) for standard architectural shingles.
How much extra for waste?
About 10% for a simple gable roof; 15% for roofs with many hips and valleys.
Planning a roofing project
Roofing quantities depend on pitch, valleys, hips, ridges, penetrations, starter strips, and local product packaging. Treat this estimate as an early budget check and confirm the final takeoff with the shingle manufacturer's installation instructions or a roofing professional.
How to use this estimate
- Measure the project in the units shown and recheck your measurements before ordering.
- Use the waste allowance as a planning buffer, not as a substitute for a detailed material takeoff.
- Compare the result with the package yield, coverage, or weight listed by your supplier.
- Prices are user-entered estimates and may change by location, product, delivery, and season.
Accuracy and limitations
Calculapedia provides educational planning estimates. It does not inspect your site, select products, guarantee quantities, or replace a contractor, engineer, architect, building official, or supplier. Confirm the final quantity and any safety or code requirements before buying or building.