Volume & capacity

Cubic feet, cubic metres and cubic yards against each other for pours, excavations and deliveries; litres against all three; US gallons and imperial gallons against litres and against cubic feet; and board feet, which is a volume in spite of its name.

Which gallon. The US gallon is 3.785 litres and the imperial gallon is 4.546, twenty per cent apart, and neither is marked on the drum — a tank specified in one and filled from a datasheet written in the other is short by a fifth before anybody has made an error. Every page here names the gallon it means in its own title rather than leaving it to the reader's flag.

What the volume weighs, and how deep to pour it — the first needs a density, the second a design.