Roof Shingle Calculator
Estimate your roof area and the number of asphalt shingle bundles you need using your roof dimensions, pitch, and waste allowance.
1. Roof dimensions
Enter the building footprint dimensions measured horizontally, eave to eave and end to end. This first version assumes a simple roof with a consistent pitch.
Enter a length and width greater than zero.
2. Roof pitch
For example, enter 6 for a 6:12 pitch. A flat roof uses 0. If you need help, use our Roof Pitch Calculator.
Enter a pitch from 0 to 36 (rise per 12 inches of run).
3. Waste allowance
Choose a planning allowance based on roof complexity. The appropriate amount can vary with valleys, hips, dormers, and shingle layout.
4. Shingle coverage
Default: 33.3 sq ft per bundle (about one-third of a roofing square). Check the coverage printed on your shingle packaging and update this value if needed.
Enter bundle coverage greater than zero.
YOUR ESTIMATE
Shingle bundles needed
Estimated bundles including 10% waste, rounded up to a whole bundle.
Results are estimates for the main shingle roof surface only. Starter strips, ridge caps, underlayment, and other accessories are not included.
How to Use the Calculator
- Enter roof length and width. Use the horizontal footprint dimensions, not the sloped roof measurements.
- Enter the roof pitch. A 6:12 roof pitch means the roof rises 6 inches for every 12 inches of horizontal run.
- Choose a waste allowance. Use a preset or enter a custom percentage to account for cuts and offcuts.
- Check bundle coverage. The default is 33.3 sq ft per bundle; verify the actual coverage on the product packaging.
- Review the estimate. The calculator estimates the sloped roof area, converts it to roofing squares, adds waste, and rounds the required bundles up.
Assumptions and Limitations
- This version assumes a simple rectangular footprint with a consistent pitch. It is not a detailed takeoff for complex roofs, multiple roof sections, or different pitches.
- Roof surface area is estimated by multiplying the rectangular footprint area by the pitch multiplier, calculated as the square root of 1 + (pitch ÷ 12)².
- One roofing square equals 100 square feet (approximately 9.29 m²).
- Shingle bundle coverage varies by product. The default is a planning assumption, not a guarantee; use the manufacturer's stated coverage.
- The waste allowance is an estimate. Actual material needs depend on roof shape, valleys, hips, dormers, shingle type, and installation pattern.
- Starter shingles, ridge caps, underlayment, nails, and other accessories are excluded. Confirm quantities with your supplier or roofing contractor.
