Roof area and shingle squares from footprint and pitch.
How to use this calculator
Every field updates the result as you type — there is no submit step. The inputs below are pre-filled with a realistic example so you can see how the tool behaves before entering your own figures.
| Field | Unit | What it means |
|---|---|---|
| Building length | ft | Enter a numeric value. |
| Building width | ft | Enter a numeric value. |
| Roof pitch (rise per 12) | /12 | Enter a numeric value. |
| Eave overhang | ft | Enter a numeric value. |
| Waste allowance | % | Enter a numeric value. |
| Price per square | $ | Enter a numeric value. |
Worked example
Using the default values loaded into the calculator above, the result is:
| Input | Value |
|---|---|
| Building length (ft) | 40 |
| Building width (ft) | 30 |
| Roof pitch (rise per 12) (/12) | 6 |
| Eave overhang (ft) | 1 |
| Waste allowance (%) | 10 |
| Price per square ($) | 120 |
| Output | Value |
|---|---|
| Roof area | 1,502.6 ft² |
| Footprint area | 1,344 ft² |
| Pitch multiplier | 1.11803 |
| Roof angle | 26.57° |
| Area with 10% waste | 1,652.9 ft² |
| Squares needed | 16.53 (17 to buy) |
| Bundles (3 per square) | 50 |
| Estimated material cost | $2,040.00 |
Reading the result
Conversion factors and physical constants used here are the standard published values. Where a result depends on a material property, local code or regional convention, that value is exposed as an input so you can match it to your situation.
For construction and electrical work, always verify against the codes that apply in your jurisdiction.
Sharing and saving a calculation
The "Copy link" button encodes every value you have entered into the page URL. Opening that link restores the calculation exactly, which makes it easy to bookmark a scenario, send it to someone else, or keep several variations side by side in separate tabs.
Frequently asked questions
What does the Roofing Calculator do?
Roof area and shingle squares from footprint and pitch.
What result do the default values produce?
With the values pre-loaded in the calculator, roof area comes to 1,502.6 ft².
Is this calculator free to use?
Yes. It is free, requires no account, and runs entirely in your browser — nothing you enter is transmitted or stored on a server.
Can I save or share a calculation?
Yes. The "Copy link" button builds a URL containing all your entered values. Anyone opening that link sees the same calculation.
How accurate is the result?
The calculation itself is exact for the inputs given. Real-world accuracy depends on how well those inputs reflect your actual situation, so review the assumptions before relying on the figure.