Shingles for a 28×40 Roof

A 28×40 footprint at a 6/12 pitch is about 12.5 roofing squares — roughly 42 bundles of architectural shingles plus 4 roll of underlayment. Set your real pitch below.

Shingle bundles

42 bundles

Roof area

1,252 sq ft1,120 sq ft footprint × 6/12 pitch

Roofing squares

12.5 squares1 square = 100 sq ft

Shingle bundles

42 bundles3 bundles/square + 10% waste; check bundle coverage

Underlayment

4 rolls30# felt, 400 sq ft/roll before overlaps; confirm product coverage

Shingle cost (est.)

$1,386$33/bundle sample price

How this estimate works

For a simple roof with one pitch, area = footprint including overhangs × √(1 + (pitch ÷ 12)²). Bundles = area ÷ 100 × 3 × your waste factor, rounded up. Check your product: bundle coverage varies. Price is an editable sample, not a local quote.

This tool is for asphalt shingles at 2/12 pitch or steeper. Between 2/12 and 4/12, special underlayment is required and the standard felt allowance is excluded. GAF low-slope application guidance.

Starter, drip edge, and ridge cap assume a simple gable with a ridge along the length. Underlayment roll coverage is before overlaps. Valleys, dormers, flashing, ice barriers, tear-off, labor, and complex roof geometry need a separate takeoff.

Planning estimate. Adjust allowances and sample prices for your supplier; tax, delivery, and labor are not included.

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Shingles for a 28×40 Roof

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