Roofing calculator
Measure the house from the ground, pick the pitch, and get the squares. The pitch factor and the waste are the two numbers people get wrong.
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How it is figured
The footprint is the flat area the roof covers, including overhangs. The pitch factor turns that into sloped area: the square root of 1 plus the pitch over 12, squared. A 6/12 pitch has a factor of 1.118, so 1,500 square feet of footprint is 1,677 square feet of roof.
A square is 100 square feet. Three bundles of architectural shingles cover a square, so bundles are squares times three. Synthetic underlayment comes in 4-square rolls, with 10-square rolls from some makers.
Waste is where new roofers lose money. A plain gable wastes about ten percent in cuts. Hips, valleys and dormers waste fifteen to twenty, because every cut at an angle throws away a piece. Count the layers coming off separately for the tear-off price.
From the quantity to the bid
The calculator gives you the material count. The bid gives the customer one price and the scope in plain words, and keeps the count as your cost math. The how to bid roofing jobs guide works the whole price with example numbers, and the roofing proposal template is the layout. Materials at cost plus markup, labor at your rate, then the job price calculator adds them up and sets the deposit.
Questions contractors ask
How many squares is a 2,000 square foot house?
It depends on the pitch and the overhang. A 2,000 square foot single-story footprint at a 6/12 pitch is about 22 squares before waste, 24 to 25 with waste. A two-story house with the same floor area has half the roof.
How many bundles of shingles in a square?
Three bundles per square for standard architectural shingles. Some heavier premium lines are four. The wrapper says the coverage.
How do I measure pitch from the ground?
A level and a tape on a ladder at the eave: hold the level flat 12 inches in from the edge and measure up to the shingles. Or read it off the gable end with a pitch gauge app. Rise over 12 is the pitch.
What else is on the roofing bid?
Tear-off by the layer, drip edge, ice and water, ridge vent, pipe boots, flashing, and a per-sheet price for bad decking. The <a href="/guides/how-to-bid-roofing-jobs">roofing bidding guide</a> prices a full tear-off line by line.
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