Roofing Calculator
Estimate the area, number of squares, and bundles of shingles needed for your roof. Includes pitch multiplier adjustments and waste factors.
House Dimensions (Base Footprint)
Note: Include overhangs (eaves) in your measurements for accuracy.
How to Measure for Roofing
Estimating roofing materials starts with determining the total surface area of the roof. Because roofs are sloped, the area is larger than the flat footprint of your house.
1. Calculate Base Area
Multiply the length and width of your house's footprint, including overhangs (eaves and rakes).Base Area = Length × Width
2. Determine Roof Pitch
Pitch is the "steepness" of the roof, measured by how many inches it rises for every 12 inches of horizontal run.
Example: A 6:12 pitch rises 6 inches for every 12 inches of run.
Steeper roofs require more material to cover the same footprint. We use a pitch multiplier to account for this.
3. Add Waste Factor
You will always need more material than the exact area due to cutting, overlap, and starter courses.
- Simple Gable Roof: 5-10% waste.
- Hip Roof (Complex): 10-15% waste.
- Valleys & Dormers: 15-20% waste.
4. Squares & Bundles
- Square: Roofing is sold by the "Square". One Square = 100 square feet.
- Bundle: For standard 3-tab or architectural shingles, there are typically 3 bundles in a square.
? Frequently Asked Questions
Typically, there are 3 bundles of standard shingles per square (100 sq ft). However, heavier architectural or specialty shingles might come with 4 bundles per square.
You can measure pitch from the attic using a level and tape measure, or use a smartphone app. Measure 12 inches horizontally from a rafter, then measure the vertical distance up to the roof deck.
The waste factor generally accounts for starter strips and ridge caps on simple roofs. For complex roofs, you should calculate linear footage for ridge caps and starter strips separately to be safe.