The cubic millimetre (or cubic millimeter; US spelling) is a unit of volume and is derived from an SI unit with the symbol mm³.
One cubic millimetre is defined as the volume of a cube with sides one millimetre in length. It is the same as a microlitre. It is equal to 0.000000001m³.
There are 1 billion cubic millimetres in a cubic metre.
The US dry gallon is a unit of volume in the US customary unit system with the symbol dry gal.
The dry gallon is equal to 268.8025 in³ or 4.404 L.
The US dry gallon is not used anywhere any more - the unit below is the dry pint and the unit above is the bushel.