Trade Math · Cubic Feet
Calculating total cubic feet
Volume is area with one more dimension. Every tank, sump, and trench you'll size in the trade comes back to cubic feet. Here's the rectangular solid, the cylinder, and the unit conversions that turn cubic feet into gallons. Locals vary. Check your local's test format.
Cheat sheet
- Rectangular solid: Volume = L × W × H
- Cylinder: Volume = π × r² × h
- Composite solids: split into known shapes, sum their volumes (or subtract a cavity from a whole).
- Conversions to memorize:
- 1 cu ft = 1,728 cu in (12³)
- 1 cu ft ≈ 7.48 gallons
- 1 gallon = 231 cu in