The cubic yard is a unit of volume derived from the imperial system of units. It uses the symbol yd³.
It equals the volume of a cube with edges that each measure 1 yard. It is equivalent to 27 ft³, 46656 in³ or ≈ 0.764554 m³.
The yard (and derivatives like the cubic yard for example) are the same in both the imperial systems and US customary systems so require less conversion systems to calculate / convert to SI or metric.
The US liquid quart is a unit of volume in the US customary system with the symbol qt.
The US liquid quart is equal to 1/4 US liquid gallons, 2 US liquid pints, 4 US liquid cups, 8 US liquid gills or 32 US fluid ounces. The SI / metric equivalent is ≈ 0.946353 L.
The US liquid quart was based on exactly 57.75 in³ which was derived from the 1959 international yard and pound agreement whereby all traditional length and volume measures were legally standardised.