Material calculator
Roof shingle calculator — squares + bundles
Estimate field shingles from a building footprint and roof pitch. It converts plan area to sloped roof area, then to roofing squares and shingle bundles.
You'll need
56 bundles
Shingle bundles
- Roofing squares
- 18.45 squares
- Sloped roof area
- 1,845 sq ft
What this assumes
- Slope factor = sqrt(1 + (6/12)^2) = 1.118.
- 1500 ft² footprint × slope factor, +10% roofing waste, then ÷100 ft² per roofing square.
- 3 bundles per square is the shingle bundle setting used here.
Coverage rates & sources
Every number this calculator uses is a published engineering constant — not an estimate we made up. Here is exactly what it assumes and where each value comes from.
- Roofing square: 100 ft²/squareSource: Universal roofing trade unit (IKO, GAF, Owens Corning)
- Standard bundles per square: 3 bundles/squareSource: IKO/GAF — standard shingles bundle 3/square (~33.3 ft²/bundle)
- Premium bundles per square: 4 bundles/squareSource: Premium/designer shingles run 4–5/square; default 4
- Slope factor: sqrt(1 + (rise/12)^2)Source: Geometry — converts horizontal plan area to actual sloped roof area
- Roof waste allowance: 10%Source: Standard roofing waste for hips, valleys, starter, ridge, and cutoffs (GAF/IKO estimating guidance; complex roofs 15%)
Before you buy
- The pitch multiplier estimates sloped area from the building footprint; it does not account for overhangs, dormers, or separate roof planes.
- Bundle count covers field shingles only; starter, hip/ridge, underlayment, drip edge, and ice-and-water shield are separate.
- Three bundles per square is standard, but some designer shingles are 4–5 bundles per square; check the wrapper before ordering.
This is a planning estimate, not a substitute for a pro's on-site measurement. For load-bearing, structural, or code-regulated work, confirm quantities with a licensed contractor.