Calculate Decomposed Granite

Decomposed Granite Calculator

Calculation Results

Total Surface Area: sq. ft.

Cubic Yards Needed: yards³

Tons Needed (Approx): tons

Estimated Material Cost:

*Tonnage calculation assumes a standard compaction density of 1.4 tons per cubic yard.

How to Calculate Decomposed Granite for Your Project

Decomposed granite (DG) is a versatile, natural landscaping material formed from the natural weathering and erosion of solid granite. It is a favorite among landscape architects for its natural look, excellent drainage, and affordability. Whether you are building a walkway, a patio, or a xeriscaped garden, knowing exactly how much material to order is crucial to staying on budget and avoiding multiple delivery fees.

The Calculation Formula

Calculating decomposed granite requires converting three-dimensional space into volume and then weight. Most suppliers sell DG by the ton, though some sell by the cubic yard. Here is the math behind our calculator:

• Step 1 (Square Footage): Length (ft) × Width (ft) = Area in Square Feet
• Step 2 (Cubic Feet): Area × (Depth in Inches / 12) = Total Cubic Feet
• Step 3 (Cubic Yards): Total Cubic Feet / 27 = Total Cubic Yards
• Step 4 (Tonnage): Total Cubic Yards × 1.4 = Estimated Tons Needed

Realistic Examples

Example 1: A Small Garden Path
Imagine you are creating a path that is 30 feet long and 3 feet wide. You want a standard depth of 3 inches for stability.
30 × 3 = 90 sq. ft.
90 × (3 / 12) = 22.5 cubic feet.
22.5 / 27 = 0.83 cubic yards.
0.83 × 1.4 = 1.16 Tons. In this case, you should order 1.25 to 1.5 tons to account for compaction.

Example 2: A Large Patio Area
A patio measuring 20 feet by 20 feet with a 4-inch depth (ideal for heavy foot traffic) would require:
20 × 20 = 400 sq. ft.
400 × (4 / 12) = 133.3 cubic feet.
133.3 / 27 = 4.93 cubic yards.
4.93 × 1.4 = 6.9 Tons. For this project, a 7-ton delivery is perfect.

Important Considerations

1. Compaction: DG is usually installed in layers and compacted with a plate compactor or roller. Because the material settles and packs down, you should always order 5-10% more than your raw calculation.
2. Stabilized vs. Natural: Stabilized DG contains a binder that keeps the granite particles together, making it more resistant to erosion. While the weight is the same, the price per ton is significantly higher.
3. The 1.4 Factor: We use a multiplier of 1.4 because one cubic yard of decomposed granite typically weighs between 2,800 and 3,000 pounds (1.4 to 1.5 tons).
4. Base Layer: For high-traffic areas, you may want a 2-inch base layer of crushed stone (road base) beneath your 2 inches of DG. Make sure to calculate these layers separately!

Installation Pro-Tip

For the best results, install DG in "lifts" of no more than 2 inches at a time. Dampen the material with a fine mist of water before compacting. This allows the fines (the dust-like particles) to filter down and lock the larger pieces into a solid, durable surface.