Construction Calculator - Water and Utility

Tank Volume Calculator

Estimate round tank volume in cubic feet and gallons.

Reviewed: August 26, 2026

Calculate Tank Volume

For the Tank Volume Calculator, enter diameter and average depth / height. It models a vertical cylindrical tank from inside diameter and liquid height and reports cubic feet and U.S. gallons.

Construction measuring tools arranged beside a residential building project

Formula used

Vertical cylindrical volume = π × (inside diameter ÷ 2)² × liquid height

Tank Volume Calculator measurement plan showing Diameter feet, Average depth / height feet

Worked tank volume example

Tank Volume Calculator example: π × (13.9 ft ÷ 2)² × 3.63 ft = 550.84 ft³. Multiplying by 7.48052 gives approximately 4,121 U.S. gallons.

Interpret gallons and flow

Use gallons as a planning capacity and rely on the manufacturer's strapping or calibration chart for inventory and custody measurements.

System effects the formula omits

Dished heads, cones, freeboard, internal equipment, horizontal orientation, wall thickness, and calibration tables make real tank capacity differ.

Questions specific to this calculation

When does a cylinder differ from actual tank capacity?

Enter inside diameter and liquid height for a vertical circular cylinder. Use actual liquid depth rather than shell height when the tank is not full.