Loose volume = bank volume × (1 + swell factor). For a 20% swell, 100 BCY becomes 120 LCY in the truck bed. The two are not interchangeable, and mixing them in a bid causes serious pricing errors.
If your unit-price line for hauling is per loose cubic yard ($X per LCY hauled), use LCY. If your unit price is per bank cubic yard ($X per BCY excavated), use BCY. Always bid each line in its native unit.
Trucks measure loose volume at the scale or by counted loads × known truck capacity. A typical tandem-axle dump holds 10-14 LCY; a tri-axle holds 14-18 LCY.