Tank Volume Calculator

How to use

1. 1Pick a Tank shape: Vertical cylinder, Horizontal cylinder, Rectangular, Horizontal capsule, or Vertical cone-bottom. The dimension fields update automatically for the shape.
2. 2Choose your input unit (m, cm, ft, or in) and type the inside dimensions: diameter for round tanks, plus length, height, width, or cone height as the shape requires.
3. 3Tap a Common tank preset (55 gal drum, 275 gal IBC tote, 20 gal aquarium, 275 gal home oil tank, 1000 gal propane, cone-bottom 500 gal) to load a worked example in one click.
4. 4Leave Include partial fill on and enter the Fill depth (the height of liquid from the bottom of the tank) to see the current filled volume in every unit. Turn the toggle off if you only need total capacity.
5. 5Read the Headline result for US gal and L, the Capacity in every unit table for all six units (US gal, Imperial gal, L, m³, ft³, bbl), and the Fill level bar for the percent full.
6. 6Click Copy summary to grab the full report (shape, dimensions, fill percent, and all six unit conversions) as plain text for a log, an order form, or a maintenance ticket.

About this tool

Tank Volume Calculator finds the total capacity and the currently filled volume of five common storage-tank shapes from a few simple measurements. Vertical cylinder uses diameter and height; horizontal cylinder uses diameter and length; rectangular uses width, length, and height; horizontal capsule is a cylinder with two hemispherical end caps; vertical cone-bottom is a cylinder on top of a downward cone. Inputs accept meters, centimeters, feet, or inches; results are shown in US liquid gallons, Imperial gallons, liters, cubic meters, cubic feet, and US oil barrels. Partial fill is the part most online calculators get wrong: a horizontal cylinder filled to depth h has a wet cross-section that is a circular segment, and this tool uses the closed-form area expression r squared times acos((r - h)/r) minus (r - h) times sqrt(2 r h - h squared), then multiplies by the cylinder length, so a 275 gallon home heating oil tank read at the dipstick lines up with the same number you would get from an integration table. Capsules add a spherical cap on each end using V = (pi h squared / 3) times (3 r - h). Cone-bottom tanks below the cylinder section use a similar smaller cone whose volume scales with fill depth cubed. Above the cone, the cylinder fills linearly. Six one-click presets cover the sizes people search for most: a 55 gallon drum, a 275 gallon IBC tote, a 20 gallon aquarium, a 275 gallon home heating oil tank, a 1000 gallon propane tank, and a 500 gallon cone-bottom tank. A live fill-level bar shows the percent full, and Copy summary exports the dimensions, fill fraction, and every unit conversion as plain text for a maintenance log, a fuel order, an aquarium build sheet, or a chemical inventory ticket. The math is exact in cubic meters and converts using exact factors (1 US gallon = 231 cubic inches, 1 imperial gallon = 4.54609 L, 1 oil barrel = 42 US gallons). Everything runs locally in your browser, so dimensions for a fuel tank, a propane installation, or a private water storage tank stay on your device.

Free to use. Works in your browser. No signup, no login.