How it works
Estimate the required amount of roofing ‘squares’ and shingle bundles based on footprint area and roof pitch.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
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?area=Total Footprint (sq ft)Number · Optional · Default: 2,000
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?pitch=Roof Pitch (rise per 12ft)Number · Optional · Default: 4
Outputs
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resultResultText · Primary output
result contains the calculator’s complete rendered result area, including its visible result cards, tables, charts, and messages.
Estimate surface area, “squares,” and bundles of shingles for your roof
Description
The Roofing Calculator is a vital project-planning tool for homeowners, contractors, and DIYers. Roofing is unique because you cannot simply measure the floor area of a house—you must account for the “Pitch” (slope) of the roof, which increases the total surface area. This tool takes your house’s Footprint Area and Roof Pitch to calculate the actual surface area, the number of Roofing Squares (the industry standard unit), and the required Bundles of Shingles.
Inputs
- House Footprint Area (sq ft): The total flat area the house covers (length x width of the building).
- Roof Pitch (rise / 12): The vertical rise for every 12 inches of horizontal run (e.g., a “4/12” pitch).
Outputs
- Roofing Squares: The number of 100-sq-ft units needed (includes a 10% waste buffer).
- Bundles of Shingles: The total number of individual bundles to purchase (typically 3 bundles per square).
Chart
- N/A: This tool provides precision numeric construction results.
“Good to Know”
- The Square: In roofing, “one square” equals exactly 100 square feet.
- The Pitch Multiplier: A steeper roof has significantly more area. For example, a 12/12 pitch (45-degree angle) has about 41% more surface area than a flat roof.
- Waste Factor: This calculator automatically adds 10% to your total. This covers shingles that are cut to fit edges, valleys, and ridges.
- Underlayment: You will typically need the same amount of underlayment (felt paper) and ice/water shield as the total roof area.
Examples
Example 1: Standard Ranch House
- Input: 1500 sq ft, 4/12 Pitch
- Output: 17.4 Squares (53 Bundles)
Example 2: Steep Victorian
- Input: 2000 sq ft, 10/12 Pitch
- Output: 28.6 Squares (86 Bundles)
Example 3: Small Shed
- Input: 200 sq ft, 6/12 Pitch
- Output: 2.5 Squares (8 Bundles)