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MaterialCalc — 1,500 sq ft Roof Replacement Cost Calculator

Estimate prepared 09/02/2026. Estimates only; verify against your plans before ordering.

1,500 sq ft Roof Replacement Cost Calculator

The area the roof covers in plan, not the roof surface itself.

Pitch decides how much bigger the roof is than the footprint.

Zero if this is new construction or you are roofing over.

%

A simple gable roof runs 5%. A cut-up roof with valleys runs 15%.

Result

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Roofing is quoted by the square — 100 square feet of roof surface — and the roof surface is always bigger than the house footprint. A 1,500 sq ft house at 6/12 pitch has about 1,680 sq ft of roof, which is 17 squares, not 15. That difference is roughly two squares of shingles nobody budgeted for.

Assumptions used

These are the numbers behind the result. Where one of them is soft, the cost range widens rather than pretending to a precision the data does not have.

Roofing square
100 ft²

Roofing is sold and quoted by the square, which is 100 square feet of roof surface.

Standard roofing convention — Published product data, checked 09/01/2026

Bundles per square
3 bundles

Three bundles of architectural shingles cover one square. Heavier designer shingles take four.

Owens Corning and GAF product data — Published product data, checked 09/01/2026

Underlayment roll coverage
10 squares

Synthetic underlayment product data — Published product data, checked 09/01/2026

Roofing nails per square
2.5 lb

Fastener coverage tables — Industry standard, varies by supplier, checked 09/01/2026

Pitch multiplier at 6/12
1.118

Roof surface is larger than the footprint. A 6/12 roof is about 12% more area than the plan view.

Geometry — sqrt(1 + (rise/run)²) — Published product data, checked 09/01/2026

Prices verified 09/01/2026 (US national average, big-box retail shelf price and regional ready-mix quotes). Regional adjustment: Blended from RSMeans city cost index bands and BLS construction wage differentials.

The formula

Roof area = footprint × pitch factor, where the factor is √(1 + (rise ÷ 12)²): 1.054 at 4/12, 1.118 at 6/12, 1.302 at 10/12. Squares = roof area ÷ 100, plus waste. Three bundles of architectural shingles per square. Tear-off is priced per square foot per existing layer.

Worked examples

1,500 sq ft footprint at 6/12, one layer off

Ground floor footprint (square feet): 1500 Roof pitch: 6 Existing layers to tear off: 1 Waste: 10

1,677 sq ft of roof — 18.5 squares with waste, about 56 bundles. The pitch alone adds nearly two squares over the footprint.

Same house at 10/12

Ground floor footprint (square feet): 1500 Roof pitch: 10 Existing layers to tear off: 1 Waste: 10

1,953 sq ft of roof. A steeper pitch costs more shingles and much more labor, because steep roofs need staging.

Roofing over, no tear-off

Ground floor footprint (square feet): 1500 Roof pitch: 6 Existing layers to tear off: 0 Waste: 10

Same materials, no disposal. Cheaper today, and it hides deck damage you will pay for at the next roof.

Choosing materials

  • Pitch is the multiplier nobody applies. Going from 4/12 to 10/12 adds 24% to the roof area of the same house — that is four extra squares on a 1,500 sq ft footprint.
  • Waste depends on the roof shape, not the size. A simple gable runs 5%; a roof with hips, valleys and dormers runs 15% because every cut at a valley is scrap.
  • Tear-off weight is what drives disposal cost. One layer over 1,680 sq ft is roughly 2 tons; three layers is 6 and needs its own dumpster with a raised weight allowance.
  • Ice and water shield at the eaves is required in most cold climates and is worth it everywhere. It is the layer that stops ice dams pushing water back under the shingles.
  • Check the deck once the old roof is off. Soft or delaminated sheathing has to be replaced, and it is the change order every roofing job risks.

Common questions

How many squares is a 1,500 sq ft roof?

It depends on pitch. At 6/12 the roof surface is about 1,680 sq ft, so 16.8 squares — 18.5 with a 10% waste allowance. At 4/12 it is 15.8 squares and at 10/12 it is 19.5.

How much does it cost to replace a 1,500 sq ft roof?

Materials typically run $2,200 to $3,600 for architectural shingles including underlayment and accessories. Installed with tear-off, roughly $7,500 to $13,000 depending on pitch, layers and region.

Why is my roof bigger than my house?

Because a sloped roof is the hypotenuse over the footprint, plus the overhangs. A 6/12 pitch makes the surface 11.8% larger than the plan area before overhangs are counted at all.

How many bundles of shingles per square?

Three bundles of standard architectural shingles cover one square. Heavier designer and luxury shingles take four, and some premium lines take five — check the bundle before ordering.

Should I tear off or roof over?

Tear off. Roofing over saves the disposal cost today and hides rotten decking, traps heat that shortens the new shingles, and most codes cap you at two total layers anyway. It is a saving you pay back with interest.

How much waste should I allow for shingles?

Five percent on a simple gable, ten on a typical roof, fifteen on anything with multiple hips, valleys and dormers. Valleys are where the scrap comes from, so count them rather than the square footage.

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