Roof size
Your prices
How the numbers are worked out
Footprint = length × width. Sloped area = footprint × pitch factor, where the factor is √(rise² + 144) ÷ 12. Squares to price = sloped area ÷ 100, and squares to order = that plus your waste factor, rounded up. Roofing is priced per square, tear-off per square, and flashing, vents, decking repair and the dumpster as flat lines. If the total is below your minimum job charge, a minimum charge adjustment brings it up to the minimum.
Example with the defaults: a 50 × 30 ft footprint is 1,500 sq ft; at 6/12 (factor 1.118) the sloped area is 1,677 sq ft, or 16.77 squares. Roofing at $475 is $7,965.75 and tear-off at $75 is $1,257.75. Add $350 flashing, $180 vents and a $450 dumpster for $10,203.50 before tax. With 12% waste you would order 19 squares of material. Rates are examples; use your own.
Tips for roofing estimates
- Price roofing and tear-off per square on separate lines; customers compare those numbers between bids.
- State the material and warranty (for example architectural shingles, 30-year manufacturer warranty) and name the underlayment you will use.
- Write down how rotten decking is handled: a per-sheet price in the estimate avoids arguments if you find damage after tear-off.
- Complex roofs with many valleys, dormers or steep pitches take longer; raise your per-square price instead of hiding it in the waste factor. Check your margin with the job price calculator and see the material waste calculator.
Frequently asked questions
How do you calculate roofing squares?
One roofing square covers 100 square feet. Multiply the length and width of each roof plane to get its footprint, add them up, then multiply by the pitch factor to get the real sloped area (a 6/12 pitch is about 1.118). Divide by 100 for squares, then add a waste factor of roughly 10 to 15 percent for cuts, starter courses and ridge.
How do roofers price per square?
Most roofers quote one installed price per square that covers shingles, underlayment, nails and labor, then add tear-off, extra layers, flashing, vents, decking repair and dumpster fees as separate lines. Prices vary by material, region and roof complexity, so the defaults on this page are examples, not market prices.
What is a pitch factor?
Roof pitch is the rise in inches per 12 inches of run. A sloped roof has more surface than the footprint under it, so you multiply the footprint by a factor: about 1.031 at 3/12, 1.118 at 6/12, 1.202 at 8/12 and 1.414 at 12/12. The factor is the square root of (rise squared plus 144) divided by 12.
Can I send this as an estimate?
Yes. Click Turn into an estimate. The roofing, tear-off, flashing and dumpster become line items in the free Estimate & Invoice Maker, where you add your logo and customer details and download a PDF. Your business details from earlier drafts are kept.
Estimates for planning only. Rates shown are examples, not market prices; use your own.
Related: Free roofing estimate template · Fence estimate calculator · Job price calculator