Decomposed Granite Calculator
Installing a decomposed granite (DG) pathway, patio, or driveway? Enter your dimensions and optional price details to calculate the exact cubic yards, tons, and 50lb bags of DG required.
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Understanding Decomposed Granite
Decomposed granite (often abbreviated as DG) consists of granite particles that have weathered down to a mixture of small flakes, gravel, and sandy rock dust. Because of its natural, earthy look and excellent drainage properties, it is extremely popular in the US for landscaping paths, patios, play areas, and driveway linings.
DG behaves differently than gravel. Standard loose gravel shifts and rolls underfoot, but compacted DG locks into a semi-firm, natural surface. This compaction means you must purchase extra material to account for the reduction in volume during tamping.
Types of Decomposed Granite
When ordering DG, you will choose between three primary varieties, each suited for different traffic and budget requirements:
| DG Type | Primary Characteristics | Best Uses |
|---|---|---|
| Loose / Natural DG | Plain weathered rock with no additives; moves and erodes slowly over time. | Garden paths, mulch replacement, low-traffic areas. |
| Stabilized DG | Pre-mixed with a dry organic binder that activates when watered, binding the particles together. | Walkways, high-traffic paths, wheelchair-accessible paths. |
| Polymeric DG | Pre-mixed with liquid polymers; creates a highly durable, asphalt-like firm surface. | Driveways, patios, high-slope paths prone to water erosion. |
Compaction allowance is mandatory
Plain DG reduces in volume by 15% to 25% once compacted with a plate compactor or hand tamper. If you calculate the exact dimensional volume and fail to add a compaction factor, your finished path will sit significantly below your garden edging.
The calculator applies a default 20% compaction allowance, which aligns with standard landscape compaction rates for a 3-inch finished layer.
| Area Dimensions | Finished Depth | Cubic Yards Needed | Tons of DG Needed |
|---|---|---|---|
| 10 × 10 ft patio | 3 inches | 1.11 cu yd | 1.61 tons |
| 50 × 4 ft walkway | 2 inches | 1.48 cu yd | 2.15 tons |
| 100 × 5 ft driveway border | 3 inches | 5.56 cu yd | 8.06 tons |
Frequently asked questions
How thick should a decomposed granite pathway be?
A standard pedestrian walkway or patio should have a finished DG thickness of 2 to 3 inches. A driveway requires 4 inches of DG poured over a compacted 4-inch gravel base layer.
Does decomposed granite wash away in rain?
Loose natural DG can wash away on slopes or during heavy downpours. Using stabilized or polymeric DG, combined with adequate slope drainage and compacted borders, dramatically reduces water erosion.
Can I install decomposed granite directly on dirt?
It is not recommended. Excavate the area, clear organic debris, lay weed barrier fabric, and place a 2-to-4-inch compacted gravel base before applying the top layer of DG. This prevents shifting and weed growth.
How do I calculate the weight of Decomposed Granite?
Uncompacted DG weighs about 1.35 tons per cubic yard. Compacted or stabilized DG is denser and weighs approximately 1.45 to 1.50 tons per cubic yard.