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Roofing Calculator

Estimate roof area, roofing squares and shingle bundles from your house size and roof pitch, with overhang and waste. Free roofing calculator.

Roof area
1,503 sq ft
Roofing squares (with waste)
16.5
Shingle bundles (3 per square)
50
Underlayment rolls (4 squares each)
5
Pitch factor
1.118
Roof angle
26.6°
Area in m²
139.6

How much roofing do I need?

A sloped roof has more area than the ground it covers. Multiply the footprint (including the overhang) by the pitch factor, √(1 + (rise ÷ 12)²). A 40 × 30 ft house with a 1 ft overhang and a 6/12 pitch has about 1,503 sq ft of roof. Roofers count in squares of 100 sq ft: with 10% waste that's 16.5 squares. Standard asphalt shingles come 3 bundles to a square, so you'd need 50 bundles. Complex roofs with valleys and dormers need 15% waste or more.

How to use it

  1. 1

    Enter the house size

    Length, width and eave overhang in feet.

  2. 2

    Pick the roof pitch

    Rise in inches per 12 inches of run.

  3. 3

    See the materials

    Roof area, squares, bundles and underlayment rolls.

Frequently asked questions

What is a roofing square?

100 square feet of roof surface.

How do I find my roof pitch?

Measure how many inches the roof rises over 12 inches horizontally. A 6-inch rise is a 6/12 pitch.

How many bundles of shingles per square?

Usually 3 for standard asphalt shingles; some heavier styles need 4.

Is anything stored?

No. The calculation runs in your browser.

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