Roofing Shingle Calculator

Measure the roof's ground footprint, pick the pitch, and the tool scales the area by the pitch multiplier (√(1 + slope²)), applies waste (10% for simple gables, 15% for cut-up roofs), and reports squares — 100 sq ft each — and bundles at the standard 3 bundles per square.

Common uses

• Sanity-check a roofer's shingle quote
• Order bundles for a garage reroof

Example

1,500 sq ft footprint, 6/12 pitch, 10% waste

1,677 sq ft sloped → 18.4 squares → 56 bundles

Limitations

• Starter strips, ridge caps, underlayment, and flashing are not included
• Heavy-weight architectural shingles can run 4+ bundles per square

How many bundles of shingles are in a square?

Three bundles per square (100 sq ft) is the standard for common three-tab and mid-weight architectural shingles, and it's what this calculator uses. Heavy designer shingles can run four or more bundles per square — check the wrapper.

How do I calculate roof area from the house footprint?

Multiply the footprint by the pitch multiplier, √(1 + (pitch/12)²). A 6/12 roof adds about 11.8% to the flat area, and a steep 12/12 roof adds 41%, so ignoring pitch seriously undershoots the order.

How much shingle waste should I allow?

10% for a simple gable roof and 15% or more for cut-up roofs with hips, valleys, and dormers, where every cut line produces offcuts. This calculator applies your chosen percentage before converting to squares and bundles.

What else do I need besides shingles for a reroof?

Underlayment, starter strips, ridge cap shingles, drip edge, flashing, and roofing nails — none of which are in this bundle count. Starter and ridge cap are usually ordered by lineal footage of eaves and ridges.

Is my roof data kept private when I use this?

Yes. The squares and bundle math runs locally in your browser — your roof dimensions are never uploaded or stored anywhere.