Decomposed Granite Calculator (DG Tonnage & Compaction)
Calculate exact quarry tons, loose cubic yards, 50-lb retail bags, and tandem dump truck loads for natural, stabilized, and resin-bound decomposed granite. Automatically factors in critical 25%–30% vibratory plate compaction loss and multi-lift layer schedules for pathways, patios, and driveways.
Measurements
US customaryHow to Calculate Decomposed Granite: The Compaction Factor
Decomposed granite (DG) is granitic rock weathered to the point of natural fracture into small gravel aggregate and fine stone sand particles. Unlike clean washed gravel (#57 stone) which maintains rigid void spaces, decomposed granite contains a continuous blend of 3/8″ aggregates down to microscopic rock flour (passing the #200 sieve). When rolled or tamped, DG shrinks by 25% to 30% in volume as fines migrate into empty spaces. Ordering exact geometric volume (Length × Width × Depth) guarantees a project shortfall.
*For a 25% compaction volume loss, divide finished volume by 0.75 (× 1.3333). Note: Multiplying finished volume by 1.25 accounts for only a 20% volume loss, leaving projects short of material.
Worked-Out Jobsite Numerical Example
Assume building a 16 ft × 14 ft outdoor patio (224 sq ft) with a finished compacted thickness of 3 inches (0.25 ft) using Stabilized Decomposed Granite and a standard 10% contingency reserve:
- Calculate Finished Compacted Volume:
224 sq ft × 0.25 ft = 56.0 compacted cubic feet56.0 ÷ 27 = 2.074 Compacted Cubic Yards
- Apply True 25% Compaction Divisor (÷ 0.75):
2.074 ÷ ( 1 − 0.25 ) = 2.074 ÷ 0.75 = 2.074 × 1.3333 = 2.765 Loose Quarry Yards
- Add 10% Edging & Spill Reserve:
2.765 × 1.10 = 3.04 Loose Cubic Yards to Order
- Convert to Quarry Tonnage (at 1.55 Tons/compacted yd³ for Stabilized DG):
2.074 comp yds × 1.55 T/yd³ × 1.10 = 3.54 Bulk Tons (7,072 lbs)
- Calculate Mass-Equivalent 50-lb Retail Bags:
7,072 lbs ÷ 50 lbs/bag = 141.4 → 142 Bags (3.55 Tons Equivalent)
Both bulk delivery (3.54 tons) and bagged purchase (142 bags = 3.55 tons) describe the exact same physical material requirement.
Technical Reference: Decomposed Granite Sieve Gradation Specifications
High-performance pathways and vehicular DG pavements require a balanced particle distribution to guarantee shear strength while retaining sufficient water permeability:
| Standard Sieve Size | Metric Opening | Target Percent Passing | Engineering Function |
|---|---|---|---|
| 3/8 Inch (9.5 mm) | 9.5 mm | 100% | Ensures zero coarse stones create tripping hazards |
| 1/4 Inch (6.3 mm) | 6.3 mm | 85 – 100% | Primary structural skeleton matrix |
| No. 4 Sieve (4.75 mm) | 4.75 mm | 55 – 75% | Interlocking particle size distribution |
| No. 10 Sieve (2.0 mm) | 2.0 mm | 35 – 55% | Coarse sand transition preventing voids |
| No. 40 Sieve (0.425 mm) | 0.425 mm | 15 – 30% | Medium fine sand binding aggregate |
| No. 200 Sieve (0.075 mm) | 0.075 mm | 5 – 12% | Microscopic mineral fines required for cohesion |
For complete 2-inch compaction lift procedures, stabilizer additive specs, and perimeter restraint details, review our in-depth Hardscape Base & Compaction Engineering Guide →
Frequently Asked Questions About Decomposed Granite
Results are estimates based on the dimensions and material assumptions entered. Actual material requirements can vary due to site conditions, material density, compaction, waste, supplier specifications, and construction methods. Confirm quantities with your supplier or project professional before ordering.