How many bundles of shingles are in a square?

The calculator counts 3 bundles per square for 3-tab shingles and 3.33 for architectural shingles. Packaging varies by product: GAF lists Timberline HDZ at 33.33 sq ft per bundle and the Owens Corning Supreme data sheet gives 100 sq ft per 3 bundles, both 3 to a square. Type the coverage from the wrapper in Coverage per bundle and the bundles become total ÷ coverage, rounded up: 1,476 sq ft at 33.3 sq ft is 45 bundles. Add shingles per bundle for a count of individual shingles.

How many squares is my roof?

Multiply the footprint by the pitch factor, add the waste and divide by 100. A 50 × 30 ft house at 4-in-12 is 1,500 × 1.054 = 1,581 sq ft of roof, 1,739 sq ft with 10% waste, so 17.4 squares and 53 bundles of 3-tab.

Should I measure the roof or the house footprint?

The footprint, measured flat from above at the walls. Type the eaves overhang in its own box and the calculator adds it to every side: a 10 × 10 ft house with a 1 ft overhang is 12 × 12 = 144 sq ft. It multiplies by the pitch factor itself, so typing the sloped roof size counts the slope twice: at 8-in-12 that over-orders by about 20%.

How much ridge cap do I need?

For a simple gable roof the ridge runs along the longer side, overhang included. The calculator adds 10% to that length and allows 35 ft per bundle, so a 40 ft ridge is 2 bundles. A hip roof also needs cap along every hip, which is not counted.

How much waste should I allow for shingles?

The calculator starts at 10%. Hips, valleys and dormers mean more cuts, so raise it for a complex roof. A 60 × 40 ft footprint at 8-in-12 with 15% waste is 33.2 squares, or 100 bundles of 3-tab. Enter a waste between 0 and 50%.

Can I enter the pitch in degrees or percent?

Yes. Choose Other pitch, then Rise per 12 in of run, Degrees or Percent grade. 30° gives an area factor of 1.155 (1 ÷ cos 30°), and 50% gives 1.118, the same as 6-in-12. A 40 × 30 ft footprint at 30° with 10% waste is 15.2 squares, 46 bundles of 3-tab. The limits are 48 in 12, 75° and 400%.

Roofing Shingle Estimator

Shingles for a roof from the footprint, eaves overhang, pitch and waste: roof area, squares, 3-tab and architectural bundles, cost and gable ridge cap. How it works

Length

Roof footprint in plan view, not the sloped surface

Width

Eaves overhang

Added to every side, so length and width each grow by twice this

Roof pitch (rise : 12)

Pitch increases actual roof area

Waste factor

Coverage per bundle (optional)

From the wrapper; 33.3 sq ft is 3 bundles per square

Shingles per bundle (optional)

Gives the individual shingle count, e.g. 21 for GAF Timberline HDZ

Price per bundle (optional)

Adds a cost line to the bundle counts

Squares

1.3

Sq ft total 132

Bundles needed

3-Tab Shingles4 bundles

Architectural Shingles5 bundles

Ridge Cap Shingles1 bundles

Ridge cap assumes a simple gable roof, so the ridge is the longer of length and width (plus 10%, 35 linear ft per bundle). Hip roofs also need cap along each hip; add that length yourself.

Area breakdown

Footprint100 sq ft

Pitch 8-in-12x1.202

Roof Surface120 sq ft

+ Waste (10%)+12 sq ft

Total132 sq ft

Ridge (gable, est.)10 linear ft

About the Roofing Shingle Estimator

A house with a 40 × 30 ft footprint and a 6-in-12 roof pitch has 1,342 sq ft of roof. With 10% waste that is 1,476 sq ft, or 14.8 squares (a square is 100 sq ft), which the shingle calculator turns into 45 bundles of 3-tab shingles at 3 bundles per square. Enter the footprint, the flat plan size of the building, not the sloped roof: the pitch factor adds the slope.

Pitch factor and shingles for a 1,000 sq ft footprint

Pitch	Pitch factor	Roof area (sq ft)	Squares with 10% waste	3-tab bundles	Architectural bundles
4-in-12	1.054	1054	11.6	35	39
5-in-12	1.083	1083	11.9	36	40
6-in-12	1.118	1118	12.3	37	41
7-in-12	1.158	1158	12.7	39	43
8-in-12	1.202	1202	13.2	40	45
9-in-12	1.250	1250	13.8	42	46
10-in-12	1.302	1302	14.3	43	48
11-in-12	1.356	1356	14.9	45	50
12-in-12	1.414	1414	15.6	47	52

A 40 × 25 ft footprint. Bundles are rounded up from squares × 3 (3-tab) and squares × 3.33 (architectural).

Frequently asked questions

How many bundles of shingles are in a square?: The calculator counts 3 bundles per square for 3-tab shingles and 3.33 for architectural shingles. Packaging varies by product: GAF lists Timberline HDZ at 33.33 sq ft per bundle and the Owens Corning Supreme data sheet gives 100 sq ft per 3 bundles, both 3 to a square. Type the coverage from the wrapper in Coverage per bundle and the bundles become total ÷ coverage, rounded up: 1,476 sq ft at 33.3 sq ft is 45 bundles. Add shingles per bundle for a count of individual shingles.
How many squares is my roof?: Multiply the footprint by the pitch factor, add the waste and divide by 100. A 50 × 30 ft house at 4-in-12 is 1,500 × 1.054 = 1,581 sq ft of roof, 1,739 sq ft with 10% waste, so 17.4 squares and 53 bundles of 3-tab.
Should I measure the roof or the house footprint?: The footprint, measured flat from above at the walls. Type the eaves overhang in its own box and the calculator adds it to every side: a 10 × 10 ft house with a 1 ft overhang is 12 × 12 = 144 sq ft. It multiplies by the pitch factor itself, so typing the sloped roof size counts the slope twice: at 8-in-12 that over-orders by about 20%.
How much ridge cap do I need?: For a simple gable roof the ridge runs along the longer side, overhang included. The calculator adds 10% to that length and allows 35 ft per bundle, so a 40 ft ridge is 2 bundles. A hip roof also needs cap along every hip, which is not counted.
How much waste should I allow for shingles?: The calculator starts at 10%. Hips, valleys and dormers mean more cuts, so raise it for a complex roof. A 60 × 40 ft footprint at 8-in-12 with 15% waste is 33.2 squares, or 100 bundles of 3-tab. Enter a waste between 0 and 50%.
Can I enter the pitch in degrees or percent?: Yes. Choose Other pitch, then Rise per 12 in of run, Degrees or Percent grade. 30° gives an area factor of 1.155 (1 ÷ cos 30°), and 50% gives 1.118, the same as 6-in-12. A 40 × 30 ft footprint at 30° with 10% waste is 15.2 squares, 46 bundles of 3-tab. The limits are 48 in 12, 75° and 400%.

Counting squares and bundles

Check a roofer's quote or an order list against the house itself. A 40 × 30 ft footprint at a 6-in-12 pitch with 10% waste is 1,476 ft² of shingles, 14.8 squares: 45 bundles of 3-tab or 50 of architectural shingles. The breakdown shows each step (1,200 ft² footprint, 1,342 ft² of sloped roof, +134 ft² waste), and a price per bundle adds a cost line.

It treats the roof as one pitch over a rectangle. For hips, valleys, dormers or mixed pitches, measure each plane, add them, and raise the waste for the extra cuts.

Pitch factor, squares and bundles

roof area = (length + 2 × overhang) × (width + 2 × overhang) × pitch factor and squares = roof area × (1 + waste ÷ 100) ÷ 100

Length and width are the wall footprint in feet; the eaves overhang is added to every side, so 10 × 10 ft with a 1 ft overhang is 144 ft². The pitch factor is √(1 + (rise ÷ 12)²): 1.054 at 4-in-12, 1.118 at 6-in-12, 1.202 at 8-in-12 (the default) and 1.414 at 12-in-12. Other pitch takes a rise up to 48 in 12, an angle up to 75° (factor 1 ÷ cos angle) or a percent grade up to 400%. Waste runs from 0 to 50%.

Bundles are rounded up from squares × 3 for 3-tab and squares × 3.33 for architectural, the calculator's own assumption. Type the coverage per bundle from the wrapper and bundles become total ÷ coverage, rounded up: GAF lists Timberline HDZ at 33.33 ft² per bundle, and Owens Corning's Supreme data sheet gives 100 ft² per 3 bundles.

The ridge cap line assumes a simple gable roof: the ridge is the longer dimension with the overhang, plus 10%, at 35 ft per bundle (2 bundles for a 40 ft ridge). Hip roofs also need cap along each hip; add that yourself. Underlayment, starter strip, drip edge and nails are not estimated.

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Roofing Shingle Estimator

Use the Roofing Shingle Estimator

Bundles needed

Area breakdown

About the Roofing Shingle Estimator

Pitch factor and shingles for a 1,000 sq ft footprint

Frequently asked questions

Counting squares and bundles

Pitch factor, squares and bundles

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