Soil Swell Factors & Weight
| Soil Type | Swell Factor | Weight (lbs/yd³) | Notes |
|---|---|---|---|
| Loam / Topsoil | 1.25 (25%) | 2,100 | Common residential soil |
| Clay | 1.35 (35%) | 2,700 | Heavy, high swell — plan extra loads |
| Sand / Gravel | 1.12 (12%) | 2,800 | Low swell, easy to work |
| Decomposed Rock | 1.40 (40%) | 3,000 | Requires ripping or hammering |
| Solid Rock | 1.55 (55%) | 4,500 | Blasting or hydraulic hammer needed |
Frequently Asked Questions
What is the swell factor in excavation?+
Swell factor is the ratio of loose (excavated) volume to bank (in-ground) volume. Soil expands when disturbed: loam by 25%, clay by 35%, sand/gravel by 12%, and solid rock by 55%. Use the loose volume to determine truck load requirements.
How many cubic yards fit in a dump truck?+
Standard tandem dump trucks hold 10–14 loose cubic yards. Tri-axle trucks hold 14–18 cubic yards. For budgeting, use 12 yd³ per load for small jobs. Confirm capacity with your hauler — weight limits (often 20–25 tons) may restrict loads before volume does for heavy soils.
How do I calculate excavation in cubic yards?+
Formula: Length (ft) × Width (ft) × Depth (ft) ÷ 27 = bank cubic yards. Then multiply by swell factor for loose cubic yards. Example: 30×20 ft at 4 ft = 2,400 cu ft ÷ 27 = 88.9 bank yd³. In clay (factor 1.35) = 120 loose yd³ to haul.
How much does excavation cost per cubic yard?+
All-in excavation (machine time + operator + hauling) typically runs $50–200 per bank cubic yard. Simple loam excavation with good access: $50–80/yd³. Rocky or confined sites: $150–300/yd³. Get multiple quotes — rates vary significantly by region and site conditions.