Enter the roof footprint, pick a pitch and roof complexity squares, bundles, and underlayment price themselves instantly.
Plan-view area (before pitch).
Roof pitch6/12 · ×1.118 area
Waste allowance: 10% — simple gables cut clean.
Labor (optional)
Total roofing squares
24.6
SQUARES
Bill of materials+10% waste
Architectural shingles
24.6 squares · 3 bundles/sq
Net 67.1 bundles · Waste +10%
Synthetic underlayment
10-sq rolls, rounded up
Net 2.24 rolls · Waste +10%
Cost projection
Saved on this device · No account · No cloud
Total · $3,199.00
24.6 squares
Pitch multiplier M = √(rise² + 12²) ÷ 12 converts plan area to true surface area a 6/12 roof has ~11.8% more surface than its footprint.
Enter the roof footprint, pick a pitch and roof complexity squares, bundles, and underlayment price themselves instantly.
Waste follows complexity: 10% simple gable, 15% hip/valley, 20% cut-up. Valleys and hips eat shingles.
Bundles = squares × 3 (rounded up); underlayment rolls = waste-adjusted area ÷ 1,000 (10-square synthetic rolls).
Area × pitch factor ÷ 100
Three bundles cover one roofing square for architectural and 3-tab shingles. The calculator totals your squares, rounds up, then multiplies by 3 — 24.6 squares means 74 bundles.
A roofing square is 100 square feet of roof surface, covered by 3 bundles of shingles. The calculator divides your pitch-adjusted, waste-loaded area by 100 to get squares.
Multiply the footprint area by the pitch multiplier M = sqrt(rise^2 + 12^2) / 12, add waste — 10% gable, 15% hip/valley, 20% cut-up — then divide by 100.
Yes. Steeper roofs have more surface per square foot of footprint — a 6/12 roof has about 11.8% more surface than its footprint. The calculator applies the pitch multiplier before adding waste.
10% for a simple gable, 15% for hips and valleys, and 20% for a complex cut-up roof with dormers and crickets. Valleys and hips eat shingles.
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