Quick answer
Multiply the footprint of the house by a pitch factor to get roof area, add 10 to 15 percent for waste, and divide by 100 to get roofing squares. Most asphalt shingles need 3 bundles per square, so a 1,500 square foot footprint at a 6/12 pitch needs about 58 bundles.
How many bundles of shingles by house footprint
Shingle bundles for a simple roof at three common pitches, with 15 percent waste and 3 bundles per square.
| House footprint | 4/12 pitch | 6/12 pitch | 8/12 pitch |
|---|---|---|---|
| 1,000 sq ft | 37 bundles | 39 bundles | 42 bundles |
| 1,200 sq ft | 44 bundles | 47 bundles | 50 bundles |
| 1,500 sq ft | 55 bundles | 58 bundles | 63 bundles |
| 1,800 sq ft | 66 bundles | 70 bundles | 75 bundles |
| 2,000 sq ft | 73 bundles | 78 bundles | 83 bundles |
| 2,500 sq ft | 91 bundles | 97 bundles | 104 bundles |
| 3,000 sq ft | 110 bundles | 116 bundles | 125 bundles |
Footprint is the ground area the roof covers, including overhangs, not the living area of the house.
How do you calculate how many bundles of shingles you need?
A sloped roof has more surface than the floor area beneath it. The calculator multiplies the house footprint by a pitch factor to convert flat area into roof area, adds waste for starter rows, ridges, valleys, and cuts, and converts the result into roofing squares of 100 square feet.
Bundles are then counted at three per square, which is standard for three-tab and most architectural asphalt shingles. Heavier designer shingles can take four or more bundles per square, so check the wrapper.
The formula
- Footprint = house length x house width, including overhangs
- Roof area = footprint x pitch factor
- Adjusted area = roof area x (1 + waste %)
- Squares = adjusted area / 100
- Bundles = squares x 3, rounded up
Worked example
With the starting values in the calculator (House length: 40 ft, House width: 28 ft, Pitch factor: 1.12, Waste buffer: 15%, Bundle price: $36), the result is 44 bundles at an estimated $1,584.
- Footprint = 40 x 28 = 1,120 sq ft
- Roof area = 1,120 x pitch factor 1.12 = 1,254.4 sq ft
- Bundles = 14.4 squares x 3, rounded up = 44
What this calculator assumes
- Three bundles of shingles cover one roofing square.
- Pitch factor defaults to 1.12, close to a 6/12 roof.
- Waste defaults to 15 percent.
- A simple roof. Dormers, valleys, and multiple levels add area and waste the footprint method cannot see.
Tips for a more accurate estimate
- Pitch factors: 3/12 = 1.031, 4/12 = 1.054, 5/12 = 1.083, 6/12 = 1.118, 8/12 = 1.202, 10/12 = 1.302, 12/12 = 1.414.
- Measure the footprint from the ground and include roof overhangs, which often add 1 to 2 feet per side.
- Use about 10 percent waste for a plain gable roof and 15 percent or more for hip roofs and roofs with valleys.
- Do not climb onto a roof to measure for an estimate. Falls are the leading cause of death in construction.
Roof Shingle Calculator FAQ
How many bundles of shingles do I need for a 2,000 square foot roof?
Two thousand square feet of actual roof surface is 20 squares, or 60 bundles before waste. With 10 percent waste that is 66 bundles, and with 15 percent it is 69.
How do I find my roof pitch factor?
The pitch factor is the square root of 1 plus the rise over run squared. A 4/12 roof is 1.054, a 6/12 roof is 1.118, an 8/12 roof is 1.202, and a 12/12 roof is 1.414.
How much does a bundle of shingles cover?
A standard bundle of asphalt shingles covers about 33.3 square feet, one third of a roofing square.
What is a roofing square?
One roofing square equals 100 square feet of roof area.
How many shingle bundles are in a square?
Many asphalt shingles use 3 bundles per square, but architectural shingles vary by product.
Is this safe for roof work?
This is only a planning calculator. Do not climb a roof unless you have the right training and safety equipment.
Use this estimate as a planning starting point. Product coverage, waste, local prices, code rules, and site conditions can change the final amount.