Roofing Calculator
Calculate how many roofing squares or bundles of shingles you need.
Enter roof dimensions and pitch to estimate materials.
Roofing Materials Needed
Roofing materials are measured in “squares” — one square covers 100 square feet (9.29 m²).
Imperial formula:
Flat Area = Length (ft) × Width (ft)
Roof Area = Flat Area × Pitch Multiplier
Squares = Roof Area / 100
Bundles = Squares × 3 (standard shingles come 3 bundles per square)
Metric formula:
Flat Area = Length (m) × Width (m)
Roof Area = Flat Area × Pitch Multiplier
Squares = Roof Area / 9.29
Pitch multipliers:
| Pitch | Multiplier |
|---|---|
| Flat (0/12) | 1.000 |
| Low (3/12) | 1.031 |
| Medium (4/12) | 1.054 |
| Standard (5/12) | 1.083 |
| Standard (6/12) | 1.118 |
| Steep (8/12) | 1.202 |
| Very steep (10/12) | 1.302 |
| Very steep (12/12) | 1.414 |
Always add 10-15% waste for cuts, overlaps, and starter strips.