What Is a Shingle Bundle Calculator?
A shingle bundle calculator estimates how many bundles of asphalt shingles you need to cover a roof. Shingles are sold by the bundle, and roofers measure coverage in squares, where one square equals 100 square feet of roof surface. Most standard 3-tab and architectural shingles take three bundles to cover one square, though heavier laminate shingles may need four.
How to Use It
Enter the length and slope width of a single roof plane in feet, the number of planes (for example 2 for a simple gable roof), a waste allowance percentage for cuts, hips, valleys and starter rows, and how many bundles your chosen shingle requires per square. The calculator returns total area, area including waste, roofing squares, and the number of bundles rounded up.
The Formula
First find the area, apply waste, convert to squares, then multiply by bundles per square:
$$\text{Bundles} = \left\lceil \frac{A \times (1 + w/100)}{100} \times b \right\rceil$$where \(A\) = total roof area in square feet, \(w\) = waste percentage, and \(b\) = bundles per square.
Worked Example
Suppose each plane is 40 ft by 20 ft and there are 2 planes, with a 10% waste allowance and 3 bundles per square:
$$A = 40 \times 20 \times 2 = 1600\,\text{sq ft}$$$$A_{adj} = 1600 \times 1.10 = 1760\,\text{sq ft}$$$$\text{Squares} = \frac{1760}{100} = 17.6$$$$\text{Bundles} = \lceil 17.6 \times 3 \rceil = \lceil 52.8 \rceil = 53$$FAQ
How many bundles are in a square? Typically three bundles cover one square (100 sq ft) for standard shingles, but always check the manufacturer label.
What waste allowance should I use? Use about 10% for simple gable roofs and up to 15–20% for complex roofs with many hips and valleys.
Does this include ridge caps and starter shingles? No. Buy extra bundles for ridge caps, hip caps, and starter courses, or increase the waste percentage accordingly.
