Roofing Material Calculator
Purchase area = measured sloping roof area × (1 + waste/100); divide by pack coverage and round up.
Inputs and units
Use the roof dimensions and slope settings shown in the form. Keep waste separate from the base roof area and match product coverage units before ordering.
Calculation method
Purchase area = measured sloping roof area × (1 + waste/100); divide by pack coverage and round up.
Worked example
The example values are: Measured roof surface area (m²) = 100; Shingle pack coverage (m²) = 3; Sheathing sheet coverage (m²) = 2.88; Extra material (%) = 10
- Area with waste (m²): 110
- Shingle packs: 37
- Sheathing sheets: 39
- Roofing squares (100 ft²): 11.8403014584
Assumptions and limitations
Measure the actual roof surface, not its horizontal footprint. Does not include flashing, ridge caps, fasteners or layout-specific sheet cuts.
Using your result
Calculate after editing the inputs. Copy result saves the displayed values; Download result saves text, and Download CSV creates a spreadsheet-friendly report. Use Print report for a paper copy. Include inputs in copied links only when you want to share them.
Roofing Material Calculator FAQs
Does this replace a roof survey?
No. Intersections, dormers, hips, valleys and product overlaps can change coverage and cutting waste.