Common question
How much roofing do I need?
Roof area is larger than the building footprint once the roof slopes. This page turns the length, width, and pitch you enter into squares, then into shingle bundles.
The result is an estimate for a simple slope. Hips, valleys, and starter courses can need more material than the waste percent covers. It is not a roofing bid.
About 14.76 squares for this roof.
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How we calculated this
A roofing square is 100 square feet. The footprint is adjusted by the pitch multiplier, the square root of rise squared plus 12 squared, divided by 12. Waste is added, then bundles assume three bundles per square and round up.
What does this mean?
This roof is about 14.76 squares, or 45 bundles, including waste. Hips, valleys, and starter courses can need more.
Your assumptions
Edit assumptions- Footprint
- 40.0 × 30.0 ft
- Pitch
- 6.0 / 12
- Waste
- 10%
This calculator provides an estimate for planning. Material yield, waste, prices, and local requirements may vary.
How the estimate is calculated
A roofing square is 100 square feet of roof surface. The pitch multiplier is the square root of rise squared plus 12 squared, divided by 12. A 6/12 pitch means you enter 6. A flat roof uses a multiplier of 1.
Surface area is length times width times that multiplier, then plus the waste percent. Bundles assume three bundles per square, which fits many asphalt shingles, and the count rounds up.
Open the Roofing Calculator · How this calculator works
Questions
What is a roofing square?
One hundred square feet of roof surface, not one hundred square feet of the ground under the house.
How do I enter pitch?
Enter the rise only. A 6/12 pitch is 6. The 12 is already in the formula.
Does this include ridge cap and starter?
No. Those are separate products. The area can still help you plan underlayment.
What if the roof has hips and valleys?
Raise the waste percent. This page measures one footprint and one pitch. It does not draw each plane.