OnlineTool.me

Tank Volume Calculator

Enter tank shape, inside dimensions, units, and fill level to get total capacity, liquid volume, and headroom.

Estimate Tank Capacity and Fill Volume

Choose a rectangular or vertical cylindrical tank, enter its inside dimensions and fill level, and get capacity plus liquid volume.

Tank capacity and current liquid volume will appear here.

How to Use Tank Volume Calculator

1

Choose Shape and Units

Select a rectangular tank or vertical cylinder and the unit system used by your measurements.

2

Enter Inside Dimensions

Measure the internal length, width, height, or diameter required for the selected shape.

3

Set the Fill Level

Enter a percentage to compare liquid volume with total capacity and remaining headroom.

Tank Volume Calculator Features

  • Rectangular and vertical cylindrical tanks
  • US gallons and metric litres
  • Capacity, liquid volume, and headroom
  • Adjustable percentage fill level

Common Use Cases

Estimate storage capacity

Calculate theoretical capacity from known inside tank dimensions.

Check liquid at a fill percentage

Compare current liquid volume with remaining theoretical headroom.

Limits and Important Notes

Result type: Planning estimate

Calculation Details

  • Choose the tank shape and measurement system.
  • Calculate cubic capacity from the inside dimensions.
  • Multiply capacity by the entered fill percentage.
  • Convert cubic feet to US gallons or cubic metres to litres.

Formula

Rectangular V=L×W×H; vertical cylinder V=π(d÷2)²H; liquid volume=capacity×fill%

Rounding

Displayed gallons and litres round to two decimals; cubic volume displays to three decimals.

Default Assumptions

  • Dimensions are internal, use one consistent unit system, and describe a regular rectangular prism or upright circular cylinder.
  • The fill percentage represents a level-proportional volume for these constant cross-section shapes.
  • US conversion uses 1 cubic foot = 7.4805194805 US gallons; metric uses 1 cubic metre = 1,000 litres.

Verified Example

Inputs: Vertical cylindrical tank, 4 ft inside diameter, 10 ft inside height, 100% full.

Calculation: π × (4÷2)² × 10 = 125.6637 ft³; × 7.4805194805.

Result: Capacity ≈ 940.03 US gallons.

Sources and Version

Version: Rectangular prism and upright full cylinder geometric model

Last verified: 2026-08-11

Update responsibility: OnlineTool.me

  • Use inside dimensions. Wall thickness, domed ends, rounded corners, internal fittings, displacement, freeboard, and unusable residual volume are excluded.
  • Only rectangular tanks and upright full cylinders are supported; horizontal cylinders and irregular vessels require level-dependent geometry.
  • Do not use this planning estimate as a certified calibration, custody-transfer measurement, or safe operating limit.

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Frequently Asked Questions