Construction & electrical
Roofing Calculator
Estimate roof area, roofing squares, and shingle bundles from roof footprint, slope pitch, and waste allowance.
Interactive calculator
Estimate roof area and shingle bundles
Use roof footprint, slope pitch, and waste allowance to estimate total roofing area, roofing squares, and shingle bundles.
Results
Roof area
118.06 m2
Roofing squares
12.71
1,271 sq ft total
Shingle bundles
39
Slope multiplier: 1.118
How to use it
- 01Enter the roof length and width in meters.
- 02Use the rise-per-12 roof pitch value to account for slope.
- 03Add a waste percentage to cover cuts, starter pieces, ridge work, and site variability.
Result guide
- Roof area is adjusted for slope instead of using only the flat footprint.
- Roofing squares convert the result into the unit commonly used in shingle estimating.
- Bundle count assumes a standard three-bundles-per-square reference for asphalt shingles.
About this calculator
Roofing material estimates need more than simple footprint area because roof pitch increases the actual surface area being covered.
A practical roofing calculator should connect slope, total area, and roofing bundles so the result is useful for both planning and supplier conversations.
Frequently asked questions
Why does pitch change the roof area so much?
Because a steeper roof has more surface area than the same building footprint measured flat on plan.
What does rise per 12 mean?
It describes how many units the roof rises vertically for every 12 units of horizontal run, such as 6/12 or 8/12.
Does this work for every roofing material?
The area math is broadly useful, but the bundle estimate is specifically framed around standard shingle-style purchasing.
Method and limitations
This calculator uses the formula and assumptions described on this page. We do not claim independent professional review. Direct references will be listed here when they support a specific rule or data source used by this calculator.
Results are estimates for general information. Verify current rules and assumptions before making financial, tax, or health decisions.
Read our Editorial and Verification Policy →Related calculators
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