Squares and bundles of shingles from the house footprint, pitch and waste
Runs in your browser. Nothing you type is sent anywhere. Updated on 24 Oct 2026.A roofing calculator starts from the house footprint, because the roof is bigger by a factor set by the pitch: 1.118 at 6/12. A 1,500 square foot footprint at 6/12 is 16.77 squares, 18.45 with 10% waste, or 56 bundles of shingles. Enter your footprint, pitch and waste.
| Pitch | Roof area | Squares with waste | Bundles |
|---|---|---|---|
| 3/12 | 1,546 sq ft | 17.01 | 52 |
| 4/12 | 1,581 sq ft | 17.39 | 53 |
| 5/12 | 1,625 sq ft | 17.88 | 54 |
| 6/12 | 1,677 sq ft | 18.45 | 56 |
| 7/12 | 1,737 sq ft | 19.1 | 58 |
| 8/12 | 1,803 sq ft | 19.83 | 60 |
| 9/12 | 1,875 sq ft | 20.63 | 62 |
| 10/12 | 1,953 sq ft | 21.48 | 65 |
| 12/12 | 2,121 sq ft | 23.33 | 71 |
Pitch is already selected under "I know the"; enter your roof pitch, such as 6 for 6/12.
Enter the "Footprint with overhangs" in square feet.
Set the "Waste allowance" and the "Bundles per square" from the shingle wrapper.
Read "Squares", the squares with waste and "Bundles", which is what to order.
Roofers, framers and building codes describe a roof's steepness in three ways: pitch as a rise over 12 (6/12), an angle in degrees (26.57), and a slope as a percentage (50%). This calculator converts between all three and then uses the pitch for the numbers a roofing or framing job needs.
Roof area and squares. The same factor, the pitch multiplier, turns the footprint of the roof (its plan area, overhangs included) into the sloped area. That holds for any roof whose planes share one pitch, hips and valleys included. Roofing is ordered in squares of 100 square feet; add a waste allowance for cutting, starter rows and ridge caps, commonly around 10 percent for a simple gable and more for a cut-up roof.
What this calculator does not do: it does not handle roofs with more than one pitch in a single calculation, hip and valley rafter lengths, or dormers, and it does not say which pitch a roofing material or local code allows. Check the shingle maker's instructions and your local building department.
The rest of the article, and all 6 questions about Roof Pitch Calculator, are on the Roof Pitch Calculator page.
Multiply the roof's footprint by the pitch multiplier to get the roof area, divide by 100 to get squares, and add waste. A 1,500 square foot footprint at 6/12 is 1,677 square feet, or 16.8 squares; with 10 percent waste that is 18.5 squares, or 56 bundles at 3 bundles a square.
A pitch multiplier is the ratio of the sloped roof area to its flat footprint, equal to the square root of 1 plus the pitch over 12, squared. It is 1.054 at 4/12, 1.118 at 6/12, 1.202 at 8/12 and 1.414 at 12/12. Multiplying the footprint by it gives the roof area.
Hold a level horizontally against the roof or a rafter, mark 12 inches along the level, and measure straight up from that mark to the roof surface. That distance in inches is the pitch over 12. You can also measure any rise and run, enter both, and the calculator converts them.
The two words are often used interchangeably. Strictly, slope is the rise over the run, written as x/12 or as a percentage, while pitch has at times meant the rise over the full span. Most US roofers and codes now say pitch or slope for the same x/12 figure, which is what this calculator uses.
Formula only: no rates or limits are read from an official source.
Still stuck? Ask about Roof Pitch Calculator and anybody who knows can answer. No account needed.
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