Roofing Shingle Calculator
How many squares and shingle bundles for your roof — from the footprint and pitch, with a waste allowance.
Your project
Total area: 0 sq ft
Material estimate only — confirm quantities against your own measurements and the product packaging before you buy. Round up and keep a little extra for cuts, waste, and mistakes.
What you need
What to buy
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Roofing squares
— sq
Roof area
— sq ft
Bundles to buy
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Shopping list
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How we calculate it
pitch multiplier = sqrt( 1 + (rise/12)^2 ) • roof area = footprint × multiplier • squares = area / 100 • bundles = round up( squares × bundles-per-square × (1 + waste) )
Assumptions & sources
- 1 roofing square = 100 sq ft; 3 bundles per square for standard asphalt shingles — source: GAF Timberline: 33.33 sq ft/bundle
- Pitch multiplier sqrt(1 + (rise/12)^2) converts flat footprint to sloped roof area (exact geometry)
- Footprint × pitch is the roof plane only — the waste allowance covers hips, valleys, ridge, starter, and cap; use ~10% simple, 15%+ complex
- Premium/designer shingles ship 4–5 bundles per square — pick your type
Formulas reviewed against manufacturer spec sheets and industry standards. Last verified 2026.
How to estimate shingles
Roofers measure in “squares” — 100 square feet of roof. Because a sloped roof has more surface than its footprint, you multiply the footprint by a pitch factor (a 6/12 roof is about 1.12×). Divide the roof area by 100 for squares, and standard shingles run three bundles per square.
Estimating like a pro
- Get the pitch right: Pitch is rise over 12 inches of run. A steeper roof has meaningfully more area — a 12/12 roof is over 1.4× its footprint.
- Waste covers the complications: The base math is the roof plane only. Hips, valleys, ridge caps, and starter courses are covered by the waste allowance — 10% for a simple gable, 15%+ for a cut-up roof.
- Buy bundles, not squares: Shingles are sold by the bundle. Three bundles cover one square of standard asphalt; premium and designer lines take four or five.
Common questions
How many bundles of shingles per square?
Three bundles per square for standard architectural or 3-tab asphalt shingles (each bundle covers about 33.3 sq ft). Premium and designer shingles take four or five.
How do I convert roof footprint to actual area?
Multiply by the pitch factor √(1 + (rise/12)²). A 6/12 roof is ~1.12×, an 8/12 is ~1.20×, and a 12/12 is ~1.41× the footprint.
How much waste should I add for roofing?
About 10% for a simple gable roof, and 15% or more for roofs with lots of hips and valleys where cutting waste is higher.