The quantity needed depends on the exposure as well as on the desired look and feel. The greater the exposure, the less cedar shingles you require.
The following are examples for the most frequently used width of exposure.
| Width of exposure | Quantity | Area covered |
| 4 in (10 cm) | 1 square | 80 ft2 (7.3 m2) |
| 5 in (12.5 cm) | 1 square | 100 ft2 (9.3 m2) |
| 6 in (15 cm) | 1 square | 120 ft2 (11.2 m2) |
Waste has to be taken into account.
ROOFS
For roofs, the steeper the slope, the greater the exposure to weather, the more cedar shingles required to lessen shingle exposure.
Also, correct exposure provides triple coverage. Remember, a good wood shingle roof can last from 25 to 30 years, even up to 50 years in some cases.
A standard bundle of white cedar shingles covers 25 sq. ft (2.3 m2) if the exposure is 5 in (12.5 cm). Cedar shingles are measured in squares, 1 square = 4 bundles.
In calculating the quantity required for a roof, you need to know the roof type, ratio of roof length to roof width, roof slope, shingle exposure, type of cedar shingle used (more breakage with lower grades), type of hip and ridge units (prefabricated or built on site) and general surface area.
WALLS
For cedar siding, calculate the total area and divide by the area covered by a square. As walls are less exposed to climate, a greater exposure can be used, and less shingles are required.
Here is a calculator that will help you find out how many bundles you need for your job.
The greater the exposure, the less shingles you require.
