When soils are excavated, they increase in volume, or swell, because of an increase in voids:

V_b = V_b L = ( 100 / ( 100 + % swell ) ) V_L

where
V_b = original volume, yd3 (m3), or bank yards

V_L = loaded volume, yd3 (m3), or loose yards

L = load factor

When soils are compacted, they decrease in volume:

V_c = V_b S

where
V_c = compacted volume, yd³ (m³)
S = shrinkage factor.

Bank yards moved by a hauling unit equals weight of load, lb (kg), divided by density of the material in place, lb (kg), per bank yard (m³).