Soil in the ground (bank volume) takes up less space than the same soil in a truck (loose volume), and compacted soil takes up less again.
Three volumes
Bank cubic yards measure material in its natural, undisturbed place. Loose cubic yards measure it after digging, when it swells. Compacted cubic yards measure it after rolling or tamping, when it shrinks.
Typical swell
Common soil can swell by roughly 20 to 30 percent when dug. Sand and gravel swell less, while clay and rock swell more. So 100 bank cubic yards may fill about 125 cubic yards of truck space.
Shrinkage
Fill that is compacted can end up 10 to 20 percent smaller than the loose volume you delivered. That is why backfill orders often run higher than the hole itself.
Putting it to use
For hauling out dirt, multiply the bank volume by 1.2 to 1.3. For ordering fill to compact, multiply the finished volume by about 1.15 to 1.25. Ask your excavator which factors they use.
Frequently asked questions
What is a swell factor?
The percentage that soil grows when it is dug up.
Why does fill shrink?
Compacting squeezes out air, which reduces the volume.
Do I need to apply factors for mulch?
Not usually. Use a waste factor instead.