Calculator

Tank Height (ft)

Current Fill Height (ft)

Total Capacity

gal

ft³

Current Volume

gal

ft³

Set the fill height equal to the tank height for the full capacity, or lower to estimate the volume currently in the tank — the tank's cross-section is treated as constant top to bottom, so this doesn't apply to a horizontal cylindrical or rounded-end tank.

Choose a tank shape, enter its dimensions, and set a fill height to calculate total and current volume.

How to Use the Tank Volume Calculator

Choose Cylindrical or Rectangular, enter the tank's dimensions and height, then set the current fill height separately from the full height — leave fill height equal to tank height to see total capacity alone.

Cylindrical: volume = π × (diameter ÷ 2)² × height
Rectangular: volume = length × width × height

Because a vertical cylinder or a rectangular box has the same cross-sectional area at every height, swapping in a shorter fill height and re-running the same formula gives the current volume directly — no lookup table or dip-stick chart needed, which is exactly why those two shapes are the ones this calculator supports.

That shortcut breaks down for a horizontal cylindrical tank — the kind used for many propane and fuel-oil tanks lying on their side — since its cross-section at a given fill level is a circular segment, not a constant shape, and the relationship between fill height and volume curves rather than scaling in a straight line. A tank shaped that way needs a dedicated horizontal-tank chart, not this calculator.