How Much Roofing for a 20×40 roof?
This calculator is pre-filled to estimate the roofing for a 20×40 roof. Change any field to match your project, and enter your local price for a precise cost.
Roofing Shingles calculator
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How to estimate roofing shingles
- Measure the sloped roof area, not the building footprint. Multiply footprint by a pitch factor (~1.05-1.25) if estimating from the ground.
- Three bundles cover one square for most architectural shingles. Add 10% for hips, valleys and starter.
- Order matching ridge cap, starter strip, underlayment and drip edge alongside the field shingles.
Frequently asked questions
How many bundles of shingles in a square?
Three bundles per square for standard architectural shingles.
What is a roofing square?
A square is 100 square feet of roof surface - the standard unit for ordering and pricing roofing.