Roof Replacement Cost Calculator (Your Prices)
Enter your roof's footprint and pitch and your own price per square and get the squares, the total and each bid side by side. Estimates for planning: no address, no phone, and the prices are yours.
Estimates for planning, not professional advice. Read the full notice.
Example: a gable roof
15 roofing square
- Roof area, with waste 1,475.8 ft²
- Squares, with waste 14.76 squares
Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.
Your project
Enter a size to see your total.
Each product is rounded up once for the whole project, so the total can be less than the items bought alone added together. A line counted from a cut layout (sheets, boards or tiles laid out piece by piece) is counted for each item and added.
Your prices
Type your own prices. They stay on this device: nothing is stored or sent, and this page has no price of its own to start from. A blank box is no price, not zero.
From your own bid or quote.
From your own bid or quote. Blank means none.
Dumpster, disposal and anything else, added up.
Ask your roofer. A roof is billed in whole steps.
Any name you will recognise.
The bid's whole price.
Optional.
Optional.
Optional.
Optional.
Shopping list
| Item | Size | Buy |
|---|---|---|
| Roofing, by the square | roofing square | 15 |
Save on this device
Saved projects
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Worked example: a gable roof
Show the working
- Roof area from the footprint and pitch 1,200 ft² × 1.118 = 1,341.64 ft²
- Add the waste allowance 1,341.640786 ft² × 1.1 = 1,475.8 ft²
- Divide by the area of one square 1,475.804865 ft² ÷ 100 ft²[1] = 14.76 squares
- Round up once, to whole squares 14.76 squares = 15 roofing squares
Assumptions
The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.
| Assumption | Value | Details and changes |
|---|---|---|
| Shingle waste allowance (gable or shed roof) | 10% | |
| Default A common allowance, not a sourced figure. Check your label or supplier. | ||
| Shingle waste allowance (hip roof, dormers, valleys) | 15% | |
| Default A common allowance, not a sourced figure. Check your label or supplier. | ||
Feet and inches, like 12' 6"
Billed squares by footprint and pitch
Roofing squares to bill for a gable roof with no overhang, by footprint and pitch, with the waste allowance added
| Pitch (rise over a 12 in run) | 30 ft by 20 ft | 40 ft by 30 ft | 50 ft by 40 ft |
|---|---|---|---|
| 4 in 12 | 7 squares | 14 squares | 24 squares |
| 6 in 12 | 8 squares | 15 squares | 25 squares |
| 8 in 12 | 8 squares | 16 squares | 27 squares |
| 12 in 12 | 10 squares | 19 squares | 32 squares |
Each count is rounded up once, to whole squares, after the waste allowance is added. A roof with dormers, valleys or an overhang needs its own sizes in the calculator.
What one roofing square is
The area of one roofing square as printed on a shingle maker's data sheet
| Figure | Data sheet |
|---|---|
| Coverage per square | 100 ft² |
Figures in the Data sheet column are per CertainTeed's data sheet, checked Nov 12, 2026.
Product names are trademarks of their owners. HoneyDoMath is not affiliated with, sponsored by or endorsed by these makers. Figures come from each maker's published sheets and are shown for information only.
Source: [1]
A square is the unit roofers bill by. The calculator divides your roof's area by it.
Questions
What is a roofing square?
The unit roofers bill by. The table on this page gives its area as a shingle maker's data sheet prints it, and the calculator divides your roof's area by it.
How do I compare roof replacement bids?
Type each bid's total in the panel. The calculator divides every bid by the same billed squares, so each shows its price per square and its gap from the lowest total.
Does it use my address?
No. It asks for no address and no phone number. Your sizes and prices stay on this device.
Sources (1)
-
Technical Data Sheet, Landmark Premium Shingles (opens in new tab), CertainTeed LLC, LandmarkPremium-TDS-CTRCOMM-015-2508-E, 08/25.
Manufacturer data.
“Shingles/Square (approx.) 66 Bundles per square 4 Coverage per square 100 square feet”
Per CertainTeed's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 1)
These are summaries of what the sources say, not professional advice. Codes and product data change. Check with your building department and the product label about your own project.
Sources
- [1] CertainTeed, Technical Data Sheet, Landmark Premium Shingles. Checked November 12, 2026. https://certainteed.widen.net/content/daknr9xdxg/pdf/LandmarkPremium-TDS-CTRCOMM-015-2508-E.pdf