How it’s calculated
Soil in the ground (bank volume) loosens when dug, so it takes up more space in the truck. That increase is the swell factor.
Example: 20 × 15 × 3 ft = 900 ft³ = 33.3 bank yd³. Common earth swells about 25%, so 41.7 loose yd³. In a 10 yd³ truck that is ⌈4.17⌉ = 5 loads.
Excavations 5 ft deep or more need a protective system (sloping, shoring or a trench box) under OSHA rules unless in stable rock.
Frequently asked questions
What is the swell factor of dirt?
Common earth or loam swells about 25% when excavated: 1 bank yd³ becomes about 1.25 loose yd³. Sand and gravel swell less (10–15%), clay more (30–40%).
How many cubic yards of dirt fit in a dump truck?
A tandem dump truck typically carries 10–14 yd³ loose. Heavy wet soil or rock may reach the weight limit before the bed is full.
How do I calculate how much dirt I am removing?
Multiply length × width × depth in feet and divide by 27 for bank cubic yards, then multiply by 1 + swell (e.g. 1.25) for the loose volume you will haul.
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Sources
- Project Development and Design Manual: Earthwork Design (shrink and swell factors) — U.S. Federal Highway Administration, Federal Lands Highway
- Trenching and Excavation Safety — U.S. Occupational Safety and Health Administration
Formulas are taken from the free public references above. Results are provided “as is” for informational and educational purposes only. See our disclaimer.
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