01
Formula
Roof area = footprint × slope factor.
Squares = roof area ÷ 100. Order squares = squares × (1 + waste ÷ 100). Bundles = order squares × bundles per square, rounded up. The slope factor is the same one the roof pitch calculator shows.
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Roofing calculator for squares and bundles
This roofing calculator estimates shingle squares from the building footprint and the pitch. It is also a roofing material calculator for bundles. It does not price tear-off, underlayment brand, or flashing.
Squares to order
9.84squares
Footprint800 sq ft
Roof area894.43 sq ft
Slope factor1.118
Bundles to order30
Planning estimate from the numbers you enter. Coverage, density, waste and price are assumptions, not a supplier quote or an engineering specification.
How it works
Squares are the sloped area divided by 100.
A roofing square is 100 square feet of roof surface. Start with the horizontal footprint, length times width, including overhangs if you want them covered. Multiply by the slope factor from the rise and run. Divide by 100 to get squares, then add waste for hips, valleys, and starter. A common planning figure is 3 bundles per square for architectural shingles. That bundles-per-square field is editable because three-tab and some designer shingles differ. Confirm the bundle coverage printed on the product.
02
Example
A 40 by 20 foot footprint at 6/12, 10% waste.
The footprint is 800 square feet. The 6/12 factor is 1.118, so the roof is about 894 square feet, or 8.94 squares. With 10% waste, order 9.84 squares. At 3 bundles per square, round up to 30 bundles.
03
Tips
Hips and valleys need more than a flat factor.
The waste percent is where you account for cuts. A simple gable can be near 10%. A cut-up roof needs more. Underlayment, drip edge, ridge cap, and nails are separate from the field-shingle bundles.
04
Equipment
Material count is not the lift.
Roofing contractors sometimes finance a boom lift or other job equipment. Dengaro accepts equipment requests from $15,000 to $2 million. The bundle count stays a material estimate.
Important questions
Know what to expect.
What does this roofing material calculator leave out?+
Ridge cap, starter strip, underlayment, ice barrier, flashing, vents, and nails. Add those from the product coverage, not from the square count alone.
Do I measure the roof or the ground?+
Enter the horizontal footprint. The pitch converts it to sloped area. If you already measured the sloped area, set the rise to 0 so the factor is 1 and the footprint is the roof.
Why three bundles per square?+
It is a common coverage for many asphalt shingles: one bundle covers about a third of a square. Read the package. Change the field if the product says otherwise.
How do overhangs get included?+
Add them to the length and width before you calculate. A footprint that stops at the wall understates the shingles.
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