The formula is length × width × height
Volume in cubic feet needs all three dimensions in feet; the calculator also accepts the result and shows the same volume in cubic yards (÷27), cubic meters and cubic inches, so you can talk to the quarry, the plumber and the engineer in their own units.
The units people mix up most
Cubic yards to cubic feet is ÷27 (3 feet per side, cubed) — the conversion behind every bulk material order. Cubic inches to cubic feet is ÷1,728 (12³) — the one that catches appliance and engine specs. The calculator does both instantly.