Roofing
Roof Square Calculator
Convert roof area into squares, the unit roofing material and labour are actually quoted in.
Result
A roofing square is 100 square feet. Most three-tab and architectural shingles run three bundles per square, but heavier designer shingles can need four or five. Check the wrapper.
Get a Free Business AuditWhat moves the number
- Actual sloped area rather than footprint.
- Waste allowance, which rises with complexity rather than with size.
- Whether the count includes the areas needing different material, such as low-slope sections.
Where this one goes wrong
Applying one waste percentage to every roof. A simple gable and a roof full of hips, valleys and dormers waste very differently, and a single figure either overbuys on the simple ones or leaves the complex ones short.
Questions
About this calculator
What is a roofing square?
One hundred square feet of roof surface. Material and labour are both commonly quoted per square, which is why converting area into squares is the first step in almost any roofing estimate.
How much waste should I allow?
It depends on the cut complexity rather than the size. Hips, valleys and dormers all generate offcuts, and a complex roof needs a noticeably higher allowance than a plain gable.
Should the allowance change by material?
Yes. Products that cut cleanly to a line waste less than those installed in courses with an exposure that has to be maintained. Check the manufacturer's guidance.
The formula
squares = (area × waste factor) ÷ 100
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How to use this calculator
- Roof area (sq ft) (sq ft). Enter your own figure; the page starts at 2,400 sq ft.
- Waste allowance (%). Enter your own figure; the page starts at 12%.
- Bundles per square. Enter your own figure; the page starts at 3.
- Material cost per square ($). Enter your own figure; the page starts at $130.
The result updates as you type, so you can try a figure, see what it does to squares needed, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Roof area (sq ft) | 2,400 sq ft |
| Waste allowance | 12% |
| Bundles per square | 3 |
| Material cost per square | $130 |
What comes out
| Result | Value |
|---|---|
| Squares needed main result | 26.9 |
| Bundles to order | 81 |
| Area including waste | 2,688.0 |
| Material cost | $3,494 |
2,400 sq ft plus 12% waste is 26.9 squares, order 81 bundles, about $3,494 in material.
How sensitive the answer is
Holding everything else steady and changing only material cost per square, this is what happens to squares needed. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Material cost per square ($) | Squares needed |
|---|---|
| $65 | 26.9 |
| $98 | 26.9 |
| $130 example above | 26.9 |
| $195 | 26.9 |
| $260 | 26.9 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Roof area (sq ft) (sq ft)
- Measured in sq ft, starting at 2,400 sq ft.
- Waste allowance (%)
- A percentage, between 0 and 50, starting at 12%.
- Bundles per square
- A number, between 0 and 10, starting at 3.
- Material cost per square ($)
- A money amount, starting at $130.
What the results tell you
| Result | What it is |
|---|---|
| Squares needed | The headline result. A decimal figure. |
| Bundles to order | A number. |
| Area including waste | A decimal figure. |
| Material cost | A money figure. |
What this cannot see
Material quantities assume a clean rectangular plane and the waste factor you enter. Valleys, hips, dormers, penetrations and a steep pitch all raise real waste, and a tear-off frequently uncovers decking that was not in the quote.
Keep going
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