ListoTradesHow the calculator works
- Roof surface. A sloped roof is bigger than the house under it. We take the house length and width plus the overhang, and multiply by the pitch factor: √(1 + (pitch ÷ 12)²). That is about 1.03 for a 3/12 roof, 1.12 for 6/12, 1.25 for 9/12 and 1.41 for 12/12.
- Squares. Roofers sell by the "square": 100 square feet. Roof surface ÷ 100 = squares.
- Waste. Cuts, valleys, hips and starter rows use extra shingles. We add 10% for a simple roof, 15% for a moderate one and 20% for a complex one, and round up to a third of a square, like a bundle.
- Materials. Squares to order × your price per square of shingles and underlayment, plus a percentage for flashing, vents, ridge cap and nails.
- Labor. Squares of real roof surface (without waste) × your installation price per square. On roofs of 9/12 or more we add 25% for safety gear and slower work.
- Tear-off. Squares × your price per layer × the number of old layers, plus a flat amount for the dumpster and disposal.
- Price. Materials + labor + tear-off = your costs. Your profit percentage is added on top.
How much does a new roof cost?
Prices change a lot by state, roof shape and material. Public cost guides place a typical asphalt shingle roof at roughly $350 to $750 per square installed, and whole-roof averages between about $9,000 and $16,000 for a typical home. Treat those as a sanity check only: your price should come from your own materials, crew and overhead. The calculator shows your price per square so you can compare it with the market.
Tips for an accurate roofing price
- Measure the real roof. If the house has several sections with different pitches, run the calculator for each section and add the results.
- Check the decking. Rotten plywood is found after the tear-off. Say in your estimate how much you charge per sheet so you are not surprised.
- Count the layers. A second layer of old shingles doubles the tear-off work and the weight to haul away.
- Include insurance and permits. Roofing has high insurance costs. Put them in your hourly rate or your profit; don't leave them out.
- Put it in writing. Turn the result into a clear estimate with the scope of work, the materials and a deposit.
Frequently asked questions
How many squares of shingles do I need for a 50 × 30 ft house?
With a 1 ft overhang and a 6/12 pitch, the roof surface is about 1,860 sq ft, or 18.6 squares. With 15% waste you order about 21.7 squares, which is about 65 bundles at 3 bundles per square.
What is a roofing square?
A square is 100 square feet of roof. Shingles are sold in bundles, and most asphalt shingles need 3 bundles to cover one square. Always check the label of the product you use.
Does this include the permit and the gutters?
No. The calculator covers shingles, underlayment, accessories, labor and tear-off. Add permits, new gutters, skylights, chimney work or deck repairs as separate lines in your estimate.
What profit percentage should I use?
Many small contractors add 15% to 30% on top of their costs. Profit is not your salary: your labor is already in the labor line. Profit pays for growth, equipment and surprises. See also the markup vs. margin calculator.