Calculator · Roofing
Roofing Calculator: How Many Bundles of Shingles Do I Need?
Enter the size of the house, the overhang and the pitch, and get the full shingle list: squares, bundles, starter strip, ridge cap, underlayment, drip edge and nails, with the cost of the shingles. It flags what the building code says about low slopes and ice barriers.
Materials ticket · Roofing
Enter your house or roof size and your shopping list prints here.
How to calculate how many shingles you need
- Measure the house and add the overhangs. A 12 in overhang adds 2 ft to the length and 2 ft to the width.
- Multiply by the pitch factor. A sloped roof is bigger than its footprint: at 6/12, 1.118 times bigger. That gives the roof area.
- Convert to squares and bundles. Divide by 100 for squares, add 10–15% for waste and multiply by 3 for bundles. Round up.
Check it with a published example: HomeGuide says a 2,000 ft² roof takes 20 squares, or 60 bundles, before waste. The calculator gives 20 squares and 60 bundles.
Shingles for common houses
Calculated with the same engine as the calculator: 12 in overhangs, 10% waste on gable roofs and 15% on hip roofs, architectural shingles at $59 a bundle. Roofs under 4/12 count two layers of underlayment.
| House and roof | Roof area | Squares with waste | Bundles | Ridge cap | Underlayment rolls | Shingles cost |
|---|---|---|---|---|---|---|
| Ranch, 50 × 30 ft, gable, 4/12 | 1,754 ft² | 19.3 | 58 | 3 | 2 | $3,422 |
| Ranch, 50 × 30 ft, hip, 4/12 | 1,754 ft² | 20.2 | 61 | 5 | 2 | $3,599 |
| Two-story, 40 × 30 ft, gable, 8/12 | 1,615 ft² | 17.8 | 54 | 2 | 2 | $3,186 |
| Two-story, 40 × 30 ft, hip, 6/12 | 1,503 ft² | 17.3 | 52 | 5 | 2 | $3,068 |
| Large home, 60 × 40 ft, gable, 6/12 | 2,911 ft² | 32 | 97 | 3 | 3 | $5,723 |
| Detached garage, 24 × 24 ft, gable, 6/12 | 756 ft² | 8.3 | 25 | 2 | 1 | $1,475 |
Roof pitch factors
How much bigger the roof is than its footprint at each pitch, and the roof area over a 1,000 ft² footprint (overhangs included):
| Pitch | Angle | Factor | Roof over 1,000 ft² |
|---|---|---|---|
| 2/12 | 9.5° | 1.014 | 1,014 ft² |
| 3/12 | 14° | 1.031 | 1,031 ft² |
| 4/12 | 18.4° | 1.054 | 1,054 ft² |
| 5/12 | 22.6° | 1.083 | 1,083 ft² |
| 6/12 | 26.6° | 1.118 | 1,118 ft² |
| 7/12 | 30.3° | 1.158 | 1,158 ft² |
| 8/12 | 33.7° | 1.202 | 1,202 ft² |
| 9/12 | 36.9° | 1.25 | 1,250 ft² |
| 10/12 | 39.8° | 1.302 | 1,302 ft² |
| 12/12 | 45° | 1.414 | 1,414 ft² |
The rest of the roof: accessories and code
- Starter strip goes along the eaves and the rakes, under the first course, to keep the edges from blowing off. A bundle of GAF Pro-Start covers about 120.33 linear feet.
- Hip and ridge cap covers the ridge and, on a hip roof, the hips. GAF Seal-A-Ridge covers 25 linear feet per bundle.
- Underlayment goes over the whole deck. A roll of GAF FeltBuster synthetic felt is 4 × 250 ft, 1,000 ft². From 2/12 to under 4/12, the International Residential Code (R905.2.2) requires two layers, and below 2/12 asphalt shingles are not allowed at all.
- Ice barrier is required where ice dams form, as your local code designates: from the eave edge to at least 24 in inside the exterior wall (IRC R905.1.2), and at least 36 in up the slope on roofs of 8/12 and steeper. GAF WeatherWatch comes in 36 in × 66.7 ft rolls.
- Drip edge is required at eaves and rakes (IRC R905.2.8.5), with pieces overlapped at least 2 in. Underlayment goes over the drip edge at the eaves and under it at the rakes.
- Nails: at least 4 per strip shingle (IRC R905.2.6), or more if the shingle maker says so: GAF asks for 6 for its WindProven warranty.
Architectural or 3-tab shingles?
Both come 3 bundles to the square. 3-tab shingles are flat, single-layer and the cheapest: $27–$45 per bundle. Architectural (dimensional or laminated) shingles are thicker, with a shadowed look, longer warranties and higher wind ratings, at $33–$85 per bundle (HomeGuide).
If you are thinking of roofing over the old shingles, check your local rules first: HomeGuide notes that most cities allow no more than 2 layers, and a roof-over shortens the life of the new roof.
Frequently asked questions
How many bundles of shingles are in a square?
3 bundles. A roofing square is 100 square feet of roof, and a bundle of standard asphalt shingles covers about a third of it: GAF Timberline HDZ, GAF's best-selling shingle, installs at 3 bundles and 64 pieces per square.
How many squares are on my roof?
Divide the roof area, not the floor area, by 100. The roof is bigger than the house: it adds the overhangs and the slope. A 40 × 30 ft house with 12 in overhangs and a 6/12 pitch has about 1,503 ft² of roof, 15 squares, before waste.
How many bundles of shingles do I need for a 2,000 square foot roof?
60 bundles for exactly 2,000 ft² (20 squares), plus 10–15% for waste, as HomeGuide suggests: 66–69 bundles. If 2,000 ft² is the size of the house, measure the roof instead: the calculator does it from the footprint and the pitch.
How do I find the pitch of my roof?
Hold a level horizontal with one end touching the roof. Twelve inches from that end, measure straight down to the roof surface. If it is 6 inches, the pitch is 6/12 (26.6°). You can also measure from the attic against a rafter, which is safer than climbing onto the roof.
How much does a bundle of shingles cost?
HomeGuide puts 3-tab shingles at $27–$45 per bundle and architectural shingles at $33–$85 per bundle, materials only. Installed, a shingle roof runs about $300–$600 per square.
How many nails do I need per square?
256 for Timberline HDZ: 64 shingles with 4 nails each, the minimum in the International Residential Code (R905.2.6). With the 6-nail pattern GAF requires for its WindProven warranty, 384. Always follow the nailing instructions on the bundle.
Sources
- GAF Timberline HDZ product page: 64 pieces, 3 bundles and 256 nails per squaregaf.com
- GAF Pro-Start Starter Strip Shingles: about 120.33 lin. ft. per bundle, at eaves and rakesgaf.com
- GAF Seal-A-Ridge hip and ridge cap shingles, 25 lin. ft. per bundle (retail listing)lenco.supplies
- GAF FeltBuster synthetic roofing felt, 4 ft × 250 ft roll (10 squares)cameronashleybp.com
- GAF WeatherWatch mineral-surfaced leak barrier, 36 in × 66.7 ft roll (2 squares)gaf.com
- Amerimax aluminum drip edge flashing, 10 ft lengths (The Home Depot)homedepot.com
- International Residential Code 2021, Chapter 9: R905.1.2 ice barriers, R905.2.2 slope, R905.2.6 attachment, R905.2.8.5 drip edgecodes.iccsafe.org
- HomeGuide: How much does it cost to shingle a roof? (November 7, 2025)homeguide.com