Shingles are sold in bundles, and a roof is measured in squares. The purchase quantity is the link between them, and the link is a number printed on the shingle you choose, not a constant. This page follows a roof from its area to whole bundles. For what a square is and how pitch changes the area, see what a roofing square is.
Area to cover = roof surface area × (1 + allowance)
Bundles = area to cover ÷ installed coverage per bundle, rounded up
Shortcut: squares to cover × bundles per square, when the product lists its coverage per square
A roofing square is always 100 sq ft as a measuring unit. A product’s own coverage is a separate fact, and the allowance is for cutting and waste, never a way to make up a difference in coverage.
A 2,400 sq ft roof surface
Say the roof’s surface measures 2,400 sq ft, already including its slope. That is 24 squares. With a 10% allowance the planner works from 2,640 sq ft · 26.4 squares, and at three bundles per square the working reads: 26.4 squares × 3 per square = 79.2 bundles.
Worked example 2,400 sq ft roof, 3 bundles per square (an example), 10% extra
| Material | Calculated | Buy |
|---|---|---|
| Shingle bundles3 bundles per square, 10% extra | 26.4 squares × 3 per square = 79.2 bundles | 80 bundles |
Coverage per bundle is the exact route
TAMKO gives three bundles per square as a rule of thumb for most three-tab and laminated shingles, and its Elite Glass-Seal and Heritage data sheets each list three. The same sheets differ in what a sales square covers: Elite lists 100 sq ft, while Heritage lists 98.4 sq ft when applied to its instructions. Three bundles covering 98.4 sq ft is 32.8 sq ft per bundle. For the same roof:
| Listed coverage | Calculated | Bundles to buy |
|---|---|---|
| 3 bundles per 100 sq ft, no allowance | 24 squares × 3 per square = 72 bundles | 72 bundles |
| 3 bundles per 98.4 sq ft (32.8 sq ft each), no allowance | 2,400 sq ft ÷ 32.8 sq ft per bundle = 73.17 bundles | 74 bundles |
| 3 bundles per 100 sq ft, 10% allowance | 26.4 squares × 3 per square = 79.2 bundles | 80 bundles |
| 3 bundles per 98.4 sq ft (32.8 sq ft each), 10% allowance | 2,640 sq ft ÷ 32.8 sq ft per bundle = 80.49 bundles | 81 bundles |
The allowance is the same in each pair; only the product’s coverage changed. Do not raise the allowance to make up a coverage difference. Enter the coverage per bundle in the planner, or the bundles per square when your product lists coverage that way. A different product can list a different count again. These examples show what you might enter, not a recommendation.
The shortcut across a few example bundles-per-square values, each assuming the 100 sq ft square:
| Bundles per square | Calculated | Bundles to buy |
|---|---|---|
| 3 | 26.4 squares × 3 per square = 79.2 bundles | 80 bundles |
| 4 | 26.4 squares × 4 per square = 105.6 bundles | 106 bundles |
| 5 | 26.4 squares × 5 per square = 132 bundles | 132 bundles |
Check the wrapper or the manufacturer’s data sheet for your own shingle.
What the allowance changes
The allowance covers trimming at edges, hips and valleys. A complex roof usually needs more than a plain one. At three bundles per square, the same roof:
| Allowance | Squares to cover | Bundles to buy |
|---|---|---|
| 0% | 2,400 sq ft · 24 squares | 72 bundles |
| 5% | 2,520 sq ft · 25.2 squares | 76 bundles |
| 10% | 2,640 sq ft · 26.4 squares | 80 bundles |
| 15% | 2,760 sq ft · 27.6 squares | 83 bundles |
This example assumes
- 2,400 sq ft is the roof surface, not the plan area of the house
- Coverage values are examples; the planner asks for your shingle’s
- 10% is an editable planning default
What is not counted
This estimates shingle bundles only. Ridge caps, starter strips, drip edge, flashing and underlayment are separate items, and nothing here judges the roof structure or its pitch.
What changes the estimate?
- Coverage per bundle (or bundles per square), which is a property of the product
- The roof surface area, including pitch
- The allowance for edges, hips, valleys and waste
- Whether the data sheet lists a different coverage per square than 100 sq ft