Roof square calculator
Enter the house footprint and the roof pitch. This roofing squares calculator turns that into roof area, squares, and bundles.
Estimate
Enter a footprint to see the estimate.
- Pitch factor
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- Roof area
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- Squares
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- Squares with waste
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- Bundles
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Most asphalt shingles come 3 bundles per square. Check your product.
This is an estimate for a simple roof. Hips, valleys, dormers and multiple levels change the numbers. Measure before you order.
Pitch factors
| Pitch | Pitch factor |
|---|---|
| 0/12 | 1.000 |
| 1/12 | 1.003 |
| 2/12 | 1.014 |
| 3/12 | 1.031 |
| 4/12 | 1.054 |
| 5/12 | 1.083 |
| 6/12 | 1.118 |
| 7/12 | 1.158 |
| 8/12 | 1.202 |
| 9/12 | 1.250 |
| 10/12 | 1.302 |
| 11/12 | 1.357 |
| 12/12 | 1.414 |
| 13/12 | 1.474 |
| 14/12 | 1.537 |
| 15/12 | 1.601 |
| 16/12 | 1.667 |
| 17/12 | 1.734 |
| 18/12 | 1.803 |
Common questions
What is a roofing square?
A roofing square is 100 square feet of roof surface. A roof of 2,200 square feet is 22 squares. Shingle orders are written in squares, not in the flat footprint of the house.
How does pitch change the roof area?
Pitch is the rise over a 12-inch run. A steeper roof has more surface than the footprint under it. Multiply the footprint by the pitch factor, the square root of 1 plus (rise divided by 12) squared. A 0/12 roof has a factor of 1.000. A 6/12 roof has a factor of 1.118, so 100 square feet of footprint is about 112 square feet of roof.
How much waste should I add?
Ten percent is a common starting allowance for a simple roof with few cuts. Hips, valleys, dormers, and a cut-up roof use more. This calculator lets you pick 10, 12, 15, or 20 percent. It is an allowance for cuts, not a count of your scrap.
How many bundles are in a square?
Most asphalt shingles are packaged three bundles to the square. Some products use a different count. Check the coverage printed on the bundle before you order. This calculator multiplies squares with waste by 3 and rounds up.
How accurate is this calculator?
It is an estimate for a simple roof. You enter one footprint and one pitch. Hips, valleys, dormers, and roofs with more than one level change the area. Measure the roof, or review a drawing, before you order material.