Turn roof area, pitch, waste and your own material and crew costs into a full replacement price for a customer quote.
Pitch factor = √(1 + (rise ÷ 12)²). A 6/12 roof has about 11.8% more surface than its footprint.
Squares = footprint × pitch factor ÷ 100. One square covers 100 sq ft.
Material squares = squares × (1 + waste %).
Labor cost = labor hours × wage × (1 + burden %).
Overhead = labor hours × overhead per labor hour.
Price = (labor + direct costs + overhead) ÷ (1 − margin %), or your minimum charge if that is higher.
A 2,000 sq ft footprint at 6/12 pitch is 22.4 squares, or 25.0 with 12% waste. At $150 a square, materials are $3,756.48. With $500 disposal and $250 permit costs, direct costs are $4,506. At 2.5 hours a square the crew needs 55.9 hours; at $24 with 22% burden, labor is $1,636.75. Overhead at $8 an hour adds $447.20. Total cost is $6,590.43, and a 20% margin gives a price of $8,238.04, about $368 per square.
Fictional numbers for illustration only.
Roofing contractors use this when they quote a full tear-off and re-roof. The calculator converts a measured footprint into roofing squares using the true slope factor for the pitch, so a steep roof is not priced like a flat one.
It is also useful after the job. Enter the actual crew hours from your time records and compare the result with what you quoted. If the gap keeps showing up on steep or cut-up roofs, adjust your hours per square for those roof types.
| Pitch | Pitch factor | Squares before waste |
|---|---|---|
| 3/12 | 1.031 | 20.6 |
| 4/12 | 1.054 | 21.1 |
| 5/12 | 1.083 | 21.7 |
| 6/12 | 1.118 | 22.4 |
| 8/12 | 1.202 | 24.0 |
| 10/12 | 1.302 | 26.0 |
| 12/12 | 1.414 | 28.3 |
A 12/12 roof has about 37% more surface than a 3/12 roof over the same footprint, before you count the slower pace and extra safety setup it needs.
Using the same fictional house as the worked example but at 10/12, the footprint gives 26.0 squares, and a cut-up layout with two dormers needs 15% waste, so about 29.9 squares of material. The crew’s own records show steep roofs take about 3.2 hours a square, not 2.5. Entering those three changes moves the job well past the 6/12 price, and the gap is mostly labor. If you quote every roof at one rate per square, the steep ones are where the margin disappears.
A steeper roof has more surface for the same footprint and is slower and riskier to work on. The pitch factor handles the extra area; your hours per square should handle the slower pace.
It depends on the roof shape and the material. Track what you actually order versus what goes on the roof and use your own average.
Yes. Raise the hours per square and disposal cost for jobs with more than one existing layer.
Margin is profit as a share of the price; markup is profit as a share of cost. A 20% margin equals a 25% markup. Mixing the two up is one of the most common reasons small contractors underprice.
No. Metal panels are ordered to length, so waste depends on the layout and trim. Use your supplier’s takeoff instead of a flat percentage.
Run the calculator for each section with its own footprint and pitch, then add the squares, hours and costs together.
EZTime records crew hours by job, so your next quote uses real numbers. Book a demo to see it with your own crews.