Tank Volume Calculator

About Tank Volume Calculation

The Tank Volume Calculator computes both total capacity and current filled volume for many shapes: vertical or horizontal cylinders, rectangular prisms, capsules (cylinder with hemispherical ends), vertical or horizontal ellipses, conical tops/bottoms, and frustums. Enter the internal dimensions in centimetres and the liquid level (“Filled, cm”), then choose litres or m³ for the result. The tool is handy when calculating the volume of a tank for water storage, aquariums, or industrial vessels. Results are shown instantly as you change inputs.

Tips and Tricks

• Measure internal sizes. Capacity depends on inside dimensions. For cylinders, measure inner diameter; for rectangular tanks measure inside length × width × height; for ellipses use inner width and height; for capsules measure diameter and the length of the cylindrical part; for conical sections and frustums measure top/bottom diameters and their heights.
• Fill level (“Filled, cm”). Enter the vertical liquid depth from the lowest point of the tank. For horizontal shapes (cylinder/ellipse) this is the depth at mid-span.
• Units and quick checks. 1 m³ = 1 000 L. If the filled height equals the total height, the filled volume will match the total volume. You can switch between litres and m³ at any time without re-entering data.
• Typical real-world ranges. Household water tanks often hold 0.5-10 m³. Small fish tanks are commonly 50-250 L, larger hobby aquariums 250-500 L.
• Accuracy tips. Use a rigid ruler/tape, measure to the nearest millimetre, and avoid parallax when reading liquid depth. Temperature and internal fittings (baffles, domes, pipes) reduce effective volume—enter the geometric dimensions only.
• Formulas used (for reference).
  Cylinder: V = π·(d/2)²·h
Rectangular prism: V = l·w·h
Capsule (cylinder + two hemispheres): V = π·(d/2)²·L + (4/3)·π·(d/2)³
Frustum: V = (π·H/3)·(R₁² + R₁·R₂ + R₂²)
• European context. For engineering work, consult relevant norms such as EN 14015 (welded vertical tanks), EN 12285 (steel tanks), EN 12573 (thermoplastic tanks) and Eurocode 3, EN 1993-4-2 (design of tanks). This calculator provides geometric volume only.

FAQs

How do I calculate the volume of a tank?

Select the correct shape, enter the internal dimensions in centimetres and the filled height, then choose litres or m³. The calculator figures out the volume of a tank automatically using formulas for the selected geometry.

How do I measure a tank for volume?

Use a tape measure on the inside: measure diameter and height for a vertical cylinder, length/width/height for a rectangular tank, or width/height/length for an elliptical tank. For conical or frustum shapes, measure both top and bottom diameters and the cone height; enter the liquid depth as the “Filled, cm”.

Which unit is used to measure gas tank volume?

This tool reports geometric capacity in litres (L) and cubic metres (m³). Pressurised gas suppliers may quote standard cubic metres (Sm³) or mass, but this calculator focuses on the container's internal volume, not the amount of compressible gas.

Can I use this for a fish tank or a water tank?

Yes. It works well as a fish tank volume calculator and a water tank volume calculator—choose the appropriate shape (often rectangular or cylindrical) and enter the inside dimensions. Results are in the metric system only.

What if I'm just figuring out the volume of a partially filled tank?

Enter the current liquid depth in the “Filled, cm” field. The tool calculates the filled volume based on the shape (for example, it uses a circular-segment area for a horizontal cylinder) so you can find the volume of a tank without filling it completely.