RoofTally

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Roof shingle calculator

A 40 ft by 30 ft gable roof at 6:12 has 1,342 sq ft of roof surface: 13.4 squares, 45 bundles of architectural shingles at 3 per square with 10% waste, 2 rolls of synthetic underlayment, 2 bundles of ridge cap, about 19 lb of nails and 15 pieces of drip edge. Type your own footprint, pitch and shape; add a wing or a garage as another section.

Roof section

3 bundles per square, 64 shingles per square (Owens Corning, Section 07 31 13 specification guide, 2013, TruDefinition Oakridge shingles, read 2026-09-20). Heavier shingles take 4 to 5 bundles per square: Owens Corning Duration Premium 4 bundles of 16, Berkshire 5 bundles of 9; IKO Crowne Slate 4, Armourshake 5. Check the bundle wrapper.

10 squares per roll (Owens Corning, Section 07 31 13 specification guide, 2013, Deck Defense synthetic underlayment, read 2026-09-20).

25 linear ft per bundle (Superarbor, GAF Seal-A-Ridge hip and ridge cap shingles, read 2026-09-20).

Installed cost, per square ($)

Result

Roof area
1,342 sq ft
Roofing squares
13.4 squares
Bundles to order (10% waste)
45 bundles
Squares to order, waste included
14.8 squares
Underlayment
2 rolls
Ridge cap (40 ft of ridge and hips)
2 bundles
Roofing nails
3,435 nails, about 18.6 lb
Drip edge (147 ft of eaves and rakes)
15 pieces of 10 ft
Installed cost range
$5,367 to $8,050
Plan area (footprint with overhang)
1,200 sq ft

Bundles, rolls and pieces are rounded up to what you buy. Nails are counted on the roof as laid (64 shingles per square x 4 nails); the cost is the installed price per square times the roof area, so waste is not priced twice. Planning quantities from manufacturer coverage figures and published cost ranges, each with its source and date: measure the roof and follow the product data sheet. Not a structural assessment.

Ordering for the whole roof? Pro prints the materials list.

Every section with its area, the totals in bundles or tiles, underlayment, ridge, nails, drip edge, waste and the cost range, printable and as an Excel file.

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How it works

Roof area = footprint (with the overhang added on every side) x the pitch multiplier, where the multiplier is the square root of 1 + (rise / 12)²: 1.118 at 6:12, 1.202 at 8:12. A roofing square is 100 sq ft. Squares to order = squares x (1 + waste); bundles = squares to order x bundles per square, rounded up. Underlayment rolls = squares to order / squares per roll, rounded up. Ridge cap bundles = (ridge + hips) / linear feet per bundle, rounded up. Nails = shingles per square x squares x 4 nails per shingle, and pounds = nails / 185 nails per pound. Drip edge pieces = (eaves + rakes) / 10 ft, rounded up. Cost = the installed price per square x the roof squares, low and high.

With the starting values, the 40 ft by 30 ft gable needs 45 bundles; the same footprint as a hip roof needs 47 bundles at 15% waste and 4 bundles of ridge cap for 100 ft of ridge and hips. At $400 to $600 per square installed (HomeAdvisor, "How Much Does a Roof Replacement Cost?", updated 17 June 2026, table "Roofing Material | Average Cost", read 2026-09-20), the gable comes to $5,367 to $8,050.

The pitch multiplier is geometry; the bundles per square, the roll coverage, the ridge cap coverage and the nail counts come from the manufacturer documents listed below, each with the date it was read. Heavier shingles take 4 to 5 bundles per square: Owens Corning Duration Premium 4 bundles of 16, Berkshire 5 bundles of 9; IKO Crowne Slate 4, Armourshake 5. Check the bundle wrapper. Every field is yours to change; the starting values only save typing. Nothing is uploaded: the sections and choices stay in your browser, so the Pro materials list can pick them up.

Sources of the starting values

UK region: lengths in metres, area in m², the installed range per m² from a UK cost guide; the squares and bundles stay as the US trade counts them.

Frequently asked questions

How many bundles of shingles are in a square?
3 for standard 3-tab and architectural shingles: IKO, "How Many Square Feet in a Bundle of Shingles", 19 July 2023, read 2026-09-20; Owens Corning lists Supreme 3-tab as "3 bundles of 26, 27, 27 shingles" and Oakridge as "Bundles per Square: 3" (Owens Corning, Section 07 31 13 specification guide, 2013, TruDefinition Oakridge shingles, read 2026-09-20). Heavier shingles take 4 to 5 bundles per square: Owens Corning Duration Premium 4 bundles of 16, Berkshire 5 bundles of 9; IKO Crowne Slate 4, Armourshake 5. Check the bundle wrapper.
How much waste should I add?
10% for a simple gable and 15% for a hip roof or one with valleys (IKO, Blueprint for Roofing, read 2026-09-20). Dormers, chimneys and skylights add cuts; type a higher figure for a complicated roof. The waste field follows the shape of your sections until you change it.
How do I measure the roof without climbing on it?
Measure the footprint of the house on the ground, wall to wall, and add the overhang on every side; then read the pitch from the attic or with a pitch gauge, or convert degrees with the pitch calculator. The calculator multiplies the footprint by the pitch multiplier, which is the same for a gable and a hip roof of one pitch. Split an L-shaped house into two rectangles and add each as a section.
How many rolls of underlayment do I need?
Squares to order divided by the roll coverage, rounded up: 10 squares per roll of synthetic (Owens Corning, Section 07 31 13 specification guide, 2013, Deck Defense synthetic underlayment, read 2026-09-20) or 4 squares per roll of #15 felt (Owens Corning, Section 07 31 13 specification guide, 2013, Fiberglas Reinforced Felt Underlayment, read 2026-09-20). The starting roof needs 2 rolls of synthetic.
How much ridge cap and how many nails?
Ridge cap: the ridge plus the hips in feet, divided by the bundle coverage, 25 linear ft for GAF Seal-A-Ridge (Superarbor, GAF Seal-A-Ridge hip and ridge cap shingles, read 2026-09-20) or 29.53 ft for IKO Hip & Ridge 12 (IKO, Hip & Ridge Class 4 / Hip & Ridge 12 technical data sheet, 04/2026, read 2026-09-20). Nails: 4 per shingle (IKO, Blueprint for Roofing, read 2026-09-20), so 320 per square of 3-tab and 256 per square of architectural, at about 185 nails to the pound (Fastener USA, "How to Calculate How Many Roofing Nails You Need", 9 February 2023, 1-1/2 in roofing nails, read 2026-09-20). High-wind areas use six nails per shingle.
Where does the cost range come from?
From a published cost guide with its year, shown under the field: HomeAdvisor, "How Much Does a Roof Replacement Cost?", updated 17 June 2026, table "Roofing Material | Average Cost", read 2026-09-20 gives $400 to $600 per square installed for architectural shingles, and other ranges for 3-tab, metal, tile, slate and wood shakes. It is a national range; a local quote replaces it. Tear-off and disposal are extra.

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