Roofing Material Calculator
Purchase area = measured sloping roof area × (1 + waste/100); divide by pack coverage and round up.
Inputs and units
- Measured roof surface area (m²): Enter your value in the format and unit shown.
- Shingle pack coverage (m²): Enter your value in the format and unit shown.
- Sheathing sheet coverage (m²): Enter your value in the format and unit shown.
- Extra material (%): Enter your value in the format and unit shown.
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
Select Calculate after changing inputs. Copy result copies the displayed output; Download result saves a text file. Reset returns the form to its example inputs. Calculations run in your browser.
Roofing Material Calculator FAQs
What method does this calculator use?
Purchase area = measured sloping roof area × (1 + waste/100); divide by pack coverage and round up.
What should I check before using the result?
Measure the actual roof surface, not its horizontal footprint. Does not include flashing, ridge caps, fasteners or layout-specific sheet cuts.