How to Estimate Decomposed Granite (DG)
Follow these steps to calculate raw DG material including the critical 25% compaction factor.
- 1
Measure Area Square Footage
Multiply walkway or patio length by width in feet.
- 2
Choose Finished Compacted Depth
Select 2 inches for light garden footpaths, 3 inches for dining patios, or 4 inches for driveways.
- 3
Add the Critical 25% Compaction Shrinkage
Decomposed granite is fluffy when dumped loose. Running a vibratory plate compactor compresses the material by 20% to 25%. You MUST order extra raw volume.
- 4
Convert Cubic Yards to Tons
Multiply compacted cubic yards by 1.4 to 1.45 tons per yard to get total quarry scale weight.
The Contractor Guide to Decomposed Granite (DG)
Decomposed granite (universally abbreviated as DG) is granite rock that has naturally weathered and fractured down to a granular blend of 1/4-inch gravel chips, coarse grit, and fine rock powder. It is one of the most aesthetically pleasing, permeable, and cost-effective hardscaping materials for drought-tolerant California xeriscaping, French country garden paths, fire pit surrounds, and bocce ball courts.
Unlike rounded pea gravel, which rolls underfoot like walking on marbles, DG particles have sharp, angular fractures. When moistened and rolled with a heavy drum or plate compactor, the fine stone powder binds the larger chips together, creating a firm, solid, wheelchair-accessible walking surface that feels natural underfoot.
However, calculating DG trips up more DIY builders than almost any other aggregate because of compaction shrinkage. DG arrives from the quarry loose and fluffy. When compacted, the material loses approximately 20% to 25% of its loose volume as fines fill voids between rocks. Ordering the exact loose cubic volume results in a finished patio that is sunken 1 inch below your edging borders!
Types of DG: Natural vs. Stabilized vs. PolyPavement Resin
Choose the correct grade for your project budget and maintenance expectations:
1. Natural / Loose DG ($40–$60 / ton): Pure quarry material with zero additives. Has the most authentic rustic look. However, heavy rains can wash ruts into slopes, and wet fine powder will stick to dog paws and boots, tracking indoors. Excellent for dry climates and budget garden beds.
2. Stabilized DG ($90–$140 / ton): Pre-blended at the quarry with an organic powdered binder (derived from plantago psyllium seeds). When watered and tamped, the binder swells and creates a cohesive, semi-flexible matrix that resists water erosion and foot traffic tracking. The contractor gold standard for residential patios and park walking trails.
3. Poly-Pavement / Resin-Infused DG ($150–$220 / ton): Blended with clear polyurethane or acrylic polymer resins. Sets up rock-hard like asphalt or concrete while retaining the natural earthy color of decomposed stone. Used for commercial ADA-compliant handicap pathways and residential driveways.
| Path / Patio Dimensions | Finished Depth | Compacted Volume | Raw Volume to Order (+25%) | Tons to Order |
|---|---|---|---|---|
| 3' × 30' Garden Path (90 sq ft) | 2 Inches | 0.56 yd³ | 0.70 yd³ | 1.0 Ton |
| 4' × 50' Walkway (200 sq ft) | 3 Inches | 1.85 yd³ | 2.31 yd³ | 3.2 Tons |
| 15' × 15' Fire Pit (225 sq ft) | 3 Inches | 2.08 yd³ | 2.60 yd³ | 3.6 Tons |
| 16' × 25' Dining Patio (400 sq ft) | 3 Inches | 3.70 yd³ | 4.63 yd³ | 6.5 Tons |
| 12' × 60' Driveway Lane (720 sq ft) | 4 Inches | 8.89 yd³ | 11.11 yd³ | 15.6 Tons |
Table 10.1: Decomposed granite tonnage and raw volume requirements including the 25% compaction factor.
Step-by-Step Installation Procedure
1. Excavate Subgrade: Excavate to total depth (3 to 4 inches for patio). Clear all sod, roots, and organic soil. Compact the native subgrade firmly with a plate compactor.
2. Install Edge Restraints: Install commercial steel edging (stake every 3 feet) or bender board. The top of the edging should match the finished grade elevation.
3. Lay Geotextile Fabric: Roll out 4.0-oz non-woven geotextile fabric. Pin securely. This prevents the DG from migrating down into subsoil mud.
4. Spread in 1.5-Inch Lifts: Never spread 3 inches all at once. Spread an initial 1.5-inch layer of DG.
5. Mist and Compact: Use a hose nozzle on mist setting to moisten the layer thoroughly until damp like brown sugar (do not saturate or form puddles). Run a plate compactor over the layer 3 to 4 passes. Repeat for the second lift until flush with edging.