Roof Shingle Calculator
A roof shingle calculator finds how many shingle bundles you need by converting roof area to squares, then multiplying by about 3 bundles per square. It adjusts for pitch and adds waste for cuts and starter courses. Enter your roof dimensions and pitch below to get the bundle count.
Enter footprint dimensions to see the materials.
Estimate only. Confirm against your local building code: stairs, framing, rebar, roofing and retaining walls are structural and code-dependent. This site does not provide engineering judgment.
How Many Bundles of Shingles Do You Need?
To find shingle bundles, calculate your roofing squares (true area divided by 100), then multiply by 3, since about 3 bundles cover one square for standard architectural shingles. A 20 square roof needs about 60 bundles before waste, or roughly 66 with 10 percent. The calculator applies the pitch and waste so you buy enough, including extra for starter and ridge courses.
Why Add Waste for Shingles?
Shingle waste covers cuts at hips, valleys and rakes, plus the starter course and ridge caps that consume extra material. Ten percent is standard for a simple gable roof, and 15 percent or more for complex roofs with many hips and valleys. Running short means a visible color-batch mismatch on a later order, so the buffer matters, and the calculator includes it.
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Frequently asked questions
- How many bundles of shingles per square?
- About 3 bundles cover one roofing square (100 square feet) for standard architectural shingles. A 20 square roof needs about 60 bundles plus waste.
- How much shingle waste should I add?
- Ten percent for a simple gable roof, 15 percent or more for complex roofs with many hips and valleys, plus starter and ridge material.