Calcoid

Roofing Calculator

Estimate asphalt shingle bundles, nails, underlayment rolls, and drip edge for any pitched roof. Applies a pitch multiplier to your footprint and returns a typical installed cost range.

Roof footprint and materials

Building outline from above, not the sloped roof area.

Between 5 and 25 percent. 10 percent covers most simple gable roofs.

Shingles to order

74 bundles

Covers 24.6 squares with waste, on 2,236 sq ft of roof.

Footprint
2,000 sq ft
Pitch
6/12 (x1.12)
Roof area
2,236 sq ft
Squares
22.36
Squares + waste
24.6
Nails
7,871
Underlayment rolls
7
Drip edge
179 ft
Installed cost range
$10,062 to $16,770

A 2,000 sq ft footprint at a 6/12 pitch (multiplier 1.118) gives 2,236 sq ft of actual roof surface. With a 10 percent waste factor that is 24.60 squares, so order 74 bundles of asphalt shingles and 7,871 roofing nails. Underlayment: 7 roll(s) at 400 sq ft each. Drip edge: 179 linear ft (perimeter estimate of 4 x sqrt of footprint). Estimated installed cost range: $10,062 to $16,770 based on a typical $4.50 to $7.50 per sq ft of roof area for a reroof.

Frequently Asked Questions about the Roofing Calculator

How do I calculate the actual roof area from my building's footprint?
Multiply the footprint (the building outline from above) by a pitch multiplier of sqrt(1 + (rise/run)^2). A 6/12 pitch gives about 1.118, an 8/12 gives 1.202, and a 12/12 (45 degrees) gives 1.414. So a 2,000 sq ft footprint at a 6/12 pitch covers 2,236 sq ft of actual sloped roof.
How many bundles of shingles do I need?
Standard 3-tab and architectural asphalt shingles take 3 bundles per roofing square (100 sq ft of installed roof). The calculator multiplies your waste-adjusted square count by 3 and rounds up. For a 2,000 sq ft footprint at 6/12 pitch with 10 percent waste, that works out to 74 bundles.
What waste factor should I pick?
Use 10 percent for a simple gable roof with straight runs. Push to 15 percent for hip roofs with more cut shingles at the seams, and 15 to 20 percent for roofs with dormers, valleys, skylights, or unusual angles. The calculator caps the input at 25 percent because anything higher usually means measuring the roof again rather than ordering more material.
How much will a new asphalt shingle roof cost?
The cost range in the result uses a typical 2026 US installed price of $4.50 to $7.50 per sq ft of actual roof area for a complete reroof. That covers labor, materials, tear-off, and dump fees. Premium architectural shingles, steeper pitches, multiple layers to remove, or hard-to-access roofs all push you toward the high end. Get at least three local bids before signing a contract.
Why does the drip edge use 4 times the square root of the footprint?
The formula 4 x sqrt(area) gives the perimeter of a square footprint. For a fixed area, a square has the smallest rectangular perimeter, so this estimate can undercount a long, irregular, or multi-wing building. Measure the actual eaves and rakes before ordering drip edge.

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