About Tank Volume Calculator

Tank Volume Calculator is a free tool for estimating the volume and capacity of tanks in every common shape — vertical and horizontal cylinders, rectangular tanks, capsules, oval and elliptical tanks, and cone-bottom and cone-top tanks — whether full or partially filled.

What this site does

Enter a tank's dimensions and the calculator returns its volume in US gallons, imperial gallons, litres, cubic feet, and cubic metres all at once. For tanks that are only partially full, it computes the filled and empty volumes using the correct geometry for each shape, including the circular-segment math that horizontal cylinders require.

Alongside the main calculator, the site offers focused guides for common real-world questions: reading a heating-oil tank by depth, comparing propane tank sizes, planning emergency water storage, and estimating a residential septic tank size.

How we approach accuracy

The calculator is built on a tested calculation engine, and the formulas and constants are documented openly on the methodology page, along with the sources used to verify them. All results are computed from ideal internal geometry, so they are close estimates rather than exact capacities — real tanks vary with wall thickness, fittings, tilt, and manufacturing tolerances.

Scope

This site focuses on storage, industrial, and utility tanks — water, fuel, oil, propane, septic, and rainwater. It does not cover aquarium or fish tank content, which is a distinct topic with different needs.

Get in touch

Questions, corrections, or suggestions are welcome. Visit the contact page to reach us.