From footprint to roofing squares
A roofing square is 100 square feet of roof surface. Because a sloped roof is longer than the ground it covers, multiply the footprint by the pitch multiplier:
Roof area = (length + 2 × overhang) × (width + 2 × overhang) × pitch multiplier
Squares = roof area × (1 + waste) ÷ 100
For a 40 × 30 ft house with 12-inch overhangs and a 6/12 roof: 42 × 32 = 1,344 sq ft, times 1.118 = 1,503 sq ft of roof. With 10% waste you order 16.5 squares.
This works for gable and hip roofs of the same pitch, because the multiplier applies to every plane equally. For mixed pitches or dormers, measure each section separately and add them.
How much waste to allow
| Roof type | Typical waste |
|---|---|
| Simple gable | 5 to 10% |
| Hip roof | 10 to 15% |
| Valleys, dormers, skylights | 15 to 20% |
Next, turn squares into bundles with the shingle calculator.
Squares for common roof areas
| Roof area | Squares | With 10% waste | With 15% waste |
|---|---|---|---|
| 800 sq ft | 8 | 8.8 | 9.2 |
| 1,200 sq ft | 12 | 13.2 | 13.8 |
| 1,600 sq ft | 16 | 17.6 | 18.4 |
| 2,000 sq ft | 20 | 22.0 | 23.0 |
| 2,400 sq ft | 24 | 26.4 | 27.6 |
| 3,000 sq ft | 30 | 33.0 | 34.5 |
A footprint is not a roof area. At 6/12 the roof is 11.8% larger than the ground under it, and at 12/12 it is 41.4% larger. The roof area calculator handles gable, hip and shed shapes, and the shingle calculator turns squares into bundles.
How many squares is my roof?
Multiply the footprint including overhangs by the pitch multiplier, then divide by 100. A 40 × 30 ft house with 1 ft overhangs and a 6/12 roof has about 1,503 sq ft of roof: 15 squares before waste, or 16.5 with 10% waste.
Frequently asked questions
How many square feet is a roofing square?
100 square feet of roof surface.
How many squares is a 2,000 sq ft house?
Usually 22 to 30 squares, depending on pitch, overhang and roof shape. A one-story 2,000 sq ft house with a 6/12 roof and 1 ft overhangs is about 24 squares plus waste.
Does a hip roof have more area than a gable?
At the same pitch and footprint, the area is the same. Hip roofs need more waste and more ridge cap because of the extra cuts.
How do you calculate roofing squares?
Divide the roof area in square feet by 100. A 1,800 sq ft roof is 18 squares. To find the area, multiply the footprint by the pitch multiplier.
How many squares is a 1,500 square foot roof?
15 squares, or 16.5 with 10% extra. A 1,500 sq ft footprint at 6/12 is 16.8 squares, because the sloped roof is larger than the ground it covers.