Calculate decomposed granite needed in cubic yards, cubic meters, cubic feet or cubic inches from length, width and depth for landscaping projects.
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DG (Decomposed Granite) Formula
The calculator treats the project area as a rectangular volume. Length and width are converted to feet, depth is converted to inches, and decomposed granite volume is converted to cubic yards.
- DG = decomposed granite amount in cubic yards
- L = length in feet
- W = width in feet
- D = depth in inches
- 12 = inches per foot
- 27 = cubic feet per cubic yard
To solve for a missing dimension, the same volume formula is rearranged:
- Calculate DG: enter length, width, and depth to find the decomposed granite volume.
- Calculate length: enter width, depth, and DG amount to find the missing length.
- Calculate width: enter length, depth, and DG amount to find the missing width.
- Calculate depth: enter length, width, and DG amount to find the missing depth.
Common DG Depths by Project Type
Depth depends on how the decomposed granite will be used. The values below are common planning depths before allowing for compaction or waste.
| Project type | Typical depth | Notes |
|---|---|---|
| Light landscape cover | 1 to 2 in | Used for decorative areas with little traffic. |
| Garden path or walkway | 2 to 3 in | Common for compacted pedestrian paths. |
| Patio or seating area | 3 to 4 in | Often compacted in lifts for a firmer surface. |
| Driveway shoulder or heavier use | 4 to 6 in | May require a prepared base layer. |
DG Volume Conversion Reference
| Unit | Equivalent |
|---|---|
| 1 cubic yard | 27 cubic feet |
| 1 cubic foot | 0.037037 cubic yards |
| 1 cubic meter | 1.30795 cubic yards |
| 1 cubic yard | 0.764555 cubic meters |
Example Problems
Example 1: Calculate DG needed
You have a path that is 20 ft long, 4 ft wide, and 3 in deep.
You need about 0.7407 cubic yards of decomposed granite before adding any extra allowance.
Example 2: Calculate depth
You have 2 cubic yards of DG for an area that is 18 ft long and 9 ft wide.
The DG will cover the area at a depth of 4 inches.
FAQ
Should you add extra decomposed granite for compaction?
Yes. Decomposed granite usually compacts after spreading and tamping. For many projects, adding about 10% extra is a practical allowance. If the surface will be heavily compacted or the area has irregular edges, you may need more.
What depth should you use for decomposed granite?
For light decorative coverage, 1 to 2 inches may be enough. For walkways, 2 to 3 inches is common. For patios or heavier use areas, 3 to 4 inches or more is often used. The finished depth should match the expected traffic and the base preparation.
Does the calculator account for irregular shapes?
The calculator uses a rectangular area formula. For an irregular project, split the space into smaller rectangles, calculate each section, and add the results together. For curved or uneven edges, add an extra allowance to reduce the risk of running short.
