Roofing Calculator
Estimate how much roofing you need by area and depth — plus bags and total cost. Switch between imperial and metric units.
Roofing Calculator
Estimate how much you need — and the cost.
- sq meters 10.22
Quick coverage reference
Roofing is measured in squares (1 square = 100 sq ft). Asphalt shingles run about 3 bundles per square (≈ 33.3 sq ft per bundle). Enter the actual roof area, not the ground footprint.
How it's calculated
- Add about 10% for waste on a simple gable roof; 15% or more for roofs with many hips, valleys, and dormers.
Source: inchcalculator.com/roofing-calculator/ (1 square = 100 sq ft, 3 bundles/square cross-checked)
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</script>How much roofing do I need?
Roofing is measured in squares, where one square = 100 sq ft of roof surface. Asphalt shingles are sold by the bundle, and it takes about 3 bundles to cover one square (≈ 33.3 sq ft per bundle). The estimate is your actual roof area — not the ground footprint — plus waste, divided by the coverage per bundle.
Use bundles = roof area (sq ft) × (1 + waste%) ÷ 33.3, rounded up. A 2,000 sq ft roof is 20 squares, or about 66 bundles before waste — closer to 73 with 10% added. Remember that a sloped roof has more surface than the floor below it, so measure the planes directly or multiply the footprint by a pitch factor.
How to measure a roof
Measure each roof plane
Length × width of every sloped section, then total them. This is the real surface area, larger than the footprint.
Or apply a pitch factor
If you only have the footprint, multiply by a pitch multiplier — about 1.12 for a 6/12 roof, 1.25 for a 9/12 — to get the sloped area.
Add a waste factor
10% for a simple gable roof; 15% or more when there are hips, valleys, and dormers that need extra cuts.
Read bundles and squares
The calculator returns bundles (and the area in squares) using 3 bundles per square.
Roofing estimate tips
A steep roof can have 25% more surface than the floor plan below it. Always estimate from the sloped area, not the footprint.
Valleys, hips, and dormers all create off-angle cuts. Budget 15% on a cut-up roof versus 10% on a plain gable.
Bundles cover the field, but you also need starter strip, ridge caps, underlayment, and drip edge — count those separately.
Roofing calculator FAQ
What is a roofing square?
A roofing square is 100 sq ft of roof surface. Roofers quote materials and labor by the square.
How many bundles of shingles are in a square?
About 3 bundles per square for standard three-tab and architectural asphalt shingles, so each bundle covers roughly 33.3 sq ft.
How many bundles of shingles do I need for 2000 square feet?
A 2,000 sq ft roof is 20 squares, about 60 bundles of field shingles, or roughly 66 once you add 10% for waste.
How do I measure my roof area?
Measure each sloped plane (length × width) and total them, or multiply the footprint by a pitch factor since a slope has more surface than the floor below.
How much waste should I add for shingles?
Add 10% for a simple gable roof, and 15% or more for roofs with hips, valleys, and dormers that require extra cuts.