Formulas used
- Rectangular: length × width × height.
- Vertical cylinder: π × (diameter ÷ 2)² × height.
- Horizontal cylinder (full): π × (diameter ÷ 2)² × length.
- 1 cubic foot = 7.48052 US gallons = 28.3168 liters.
Example
A vertical tank 10 ft in diameter and 10 ft tall: π × 5² × 10 = 785.4 ft³ ≈ 5,875 gallons.
Measuring tips
Measure inside dimensions when possible; wall thickness and insulation reduce usable volume. Results show full (brim) capacity — most tanks are not filled to the top, and some have sloped bottoms or internal structures.
From tank volume to truckloads
Once you know gallons, use the Water Hauling Calculator to estimate loads, and the Fluid Weight Calculator to check whether weight will limit each load.
Frequently asked questions
Does this calculate partially filled horizontal tanks?
No — it calculates full capacity. Partial-fill volume in a horizontal tank is not linear with depth.
Which units can I use?
Inches, feet or meters. Results are always shown in gallons, cubic feet and liters.