Enter your roof footprint and pitch to estimate the roof area, squares and shingle bundles needed.
How the roofing calculator works
Roofs are larger than their footprint because of the slope. This calculator multiplies your footprint by a pitch factor to estimate the true roof area, then converts it into roofing squares and shingle bundles with a waste allowance.
It’s a planning estimate — confirm with your supplier before ordering.
Step by step
- Enter the building footprint length and width.
- Choose the roof pitch.
- Add a waste allowance and read the squares and bundles.
How the number is calculated
roof area = footprint × pitch factor × (1 + waste)
squares = roof area ÷ 100 · bundles ≈ squares × 3
A worked example
As an example, with a roof pitch of 8/12, waste of 10%, the calculator returns a roof area of 1,587. Underneath, Footprint area comes out at 1,200 ft² and Roof area at 1,587 ft². Change any field and every figure updates as you type.
Questions people ask about this
What is a roofing square?
100 square feet of roof area. Shingles are usually sold by the bundle, with about three bundles per square.
Why multiply by a pitch factor?
A sloped roof has more surface than the flat footprint below it. Steeper pitches have larger factors.
How much waste should I add?
About 10% for simple roofs, more for complex ones with lots of hips, valleys and cuts.