Squares and shingle bundles for a gable or hip roof, from the footprint and the pitch.
Roofing calculator
41 bundles of shingles13.42 squares · 6/12 pitch
- Plan area
- 1,200.00 SF
- Pitch factor
- × 1.1180
- Roof area
- 1,341.64 SF
- Squares
- 13.42 squares
- Bundles
- 41 bundles
- Nails (4 per shingle)
- 3,435 nails
- Eaves
- 80' 0"
- Rakes
- 67' 1"
- Ridge
- 40' 0"
- Drip edge
- 15 pieces of 10'
These sketches are here to help you order material and price the work quickly. They are not engineered or shop drawings — always build from your approved project drawings.
Measure to the outside of the overhangs. Length runs along the ridge.
Pitch (rise per 12")Adjust▾
No waste is added unless you enter it — hips, valleys and cut-up roofs need more. Most architectural shingles are 3 bundles per square; check the wrapper.
Show the math▾
- Plan arealength × width (to the outside of the overhangs)40' 0" × 30' 0" = 1,200.00 SF
- Pitch factor√(1 + (6 ÷ 12)²)√(1 + 0.25) = 1.1180
- Roof areaplan area × pitch factor1,200.00 SF × 1.1180 = 1,341.64 SF
- Bundlesroof area ÷ 100 SF per square × 3 bundles per square, rounded up1,341.64 SF ÷ 100 SF = 13.42 squares × 3 = 41
- Nails256 per square (4 per shingle)13.42 × 256 = 3,435
- Edges2 × length + 4 × (width ÷ 2) × pitch factor80' 0" + 67' 1" = 147' 1"
- Ridgelength40' 0" = 40' 0"
Where the numbers come from
- Pitch factor: √(1 + (rise ÷ 12)²) — 4/12 = 1.0541 · 6/12 = 1.1180 · 8/12 = 1.2019 · 12/12 = 1.4142Pythagoras: every 12" of plan run climbs the rise, so the slope is √(12² + rise²) ÷ 12 longer. On a gable or hip roof with one pitch every plane gets the same factor, so roof area = plan area × factor either way. Dormers, valleys and different pitches need their own areas.
- Minimum slope for asphalt shingles: IRC R905.2.2: 2/12 or steeper; 2/12 up to 4/12 needs double underlaymentSummary of the International Residential Code as adopted by a city building department. Check the edition your jurisdiction uses; high-wind areas also need more nails per shingle.Source
- Shingles per square: 3 bundles, 64 shingles, 256 nails per square (100 SF)GAF Timberline HDZ spec sheet. Check: a 39⅜" shingle at 5⅝" exposure covers 39.375 × 5.625 = 221.5 in², × 64 = 98.4 SF ≈ one square. Other shingles may be 4 or 5 bundles per square — change it under Adjust. Starter strip and ridge cap are separate products; hips, ridge and valleys add cutting — enter waste.Source
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