How to Use the Tank Volume Calculator
This tank volume calculator helps you find the total capacity of any container, as well as the volume of liquid currently in the tank. Select your tank shape, choose between metric (cm) and imperial (inches) units, enter the dimensions, and optionally provide the fill height to calculate the filled volume. You can also estimate liquid costs using one of 44 supported world currencies.
Supported Tank Shapes
The calculator supports ten different tank shapes:
- Vertical Cylinder — a standard upright cylindrical tank (diameter + height)
- Horizontal Cylinder — a cylinder lying on its side (diameter + length)
- Rectangular Prism (Box) — any box-shaped tank (length × width × height)
- Vertical Capsule — cylinder with hemispherical caps, standing upright
- Horizontal Capsule — cylinder with hemispherical caps, lying horizontally
- Vertical Oval (Elliptical) — an elliptical cross-section tank, standing upright
- Horizontal Oval (Elliptical) — an elliptical cross-section tank, lying horizontally
- Cone Bottom — vertical cylinder with a cone-shaped bottom
- Cone Top — vertical cylinder with a cone-shaped top
- Frustum (Truncated Cone) — a funnel-shaped tank with different top and bottom diameters
Cylindrical Tank Volume Formula
For a vertical cylinder, the volume is calculated as the area of the circular base multiplied by the height:
V = π × r² × h
where r is the radius (diameter ÷ 2) and h is the height. For a horizontal cylinder, the total volume uses the same formula with length substituted for height. The partially-filled volume of a horizontal cylinder uses the integration formula for a circular segment:
V_filled = L × [r² × arccos((r − f)/r) − (r − f) × √(2rf − f²)]
where f is the fill height and L is the length.
Rectangular Tank Volume
For a rectangular prism (box) tank:
V = L × W × H
The filled volume is simply V_filled = L × W × f, where f is the fill height.
Capsule Tank Volume
A capsule tank consists of a cylinder in the middle and two hemispheres on each end. Its volume is:
V = π × r² × body_length + (4/3) × π × r³
where body_length is the length of the cylindrical section only. The fill-height calculation accounts for the hemispherical bottom cap, the cylindrical body, and the hemispherical top cap.
Elliptical Tank Volume (Oval Tank)
For an elliptical (oval) cylinder tank:
V = π × a × b × h
where a and b are the semi-axes (half of width and half of depth) and h is the height or length. For a vertical oval tank, the fill volume scales linearly with fill height. For a horizontal oval tank, the fill volume uses the elliptical segment area formula.
Cone Bottom and Cone Top Tanks
A cone bottom tank has a cylindrical upper section and an inverted cone at the bottom. Its total volume is:
V = π × r² × cylinder_height + (1/3) × π × r² × cone_height
The partially filled volume tracks whether the liquid is still inside the conical section or has risen into the cylinder. Cone top tanks follow the same total-volume formula but filling proceeds from the flat bottom upward into the cone.
Frustum Volume (Truncated Cone Tank)
A frustum (truncated cone) has a circular bottom with radius R and a circular top with radius r. Its volume is:
V = (π/3) × h × (R² + R×r + r²)
The partially filled frustum uses the same formula applied only up to fill height f, with the intermediate radius calculated by linear interpolation.
American and Metric Units
The calculator accepts dimensions in either centimeters (metric) or inches (imperial/American). Results are always shown in all four volume units simultaneously:
- Liters (L) — standard metric volume unit
- US Gallons (gal) — 1 US gal = 231 in³ ≈ 3.785 L
- Cubic feet (ft³) — 1 ft³ = 1728 in³ ≈ 28.317 L
- Cubic inches (in³) — base imperial volume unit
- cm³ / in³ — native unit matching your input
Liquid Cost Estimation
By expanding the optional Liquid Cost Estimation section, you can enter the price per liter (metric) or price per US gallon (imperial) and select from 44 world currencies including USD, EUR, GBP, JPY, CNY, INR, BRL, and many more. The calculator will show the total cost to fill the tank completely, and the cost of the current fill level if a fill height was provided.
Fill Height and Fill Level
The Fill Height field is optional. If you leave it blank, only the total tank capacity is calculated. If you enter a fill height, the calculator also computes the volume of liquid in the tank and displays a fill-level percentage with a color-coded progress bar:
- ■ Green — under 25% full
- ■ Blue — 25–75% full
- ■ Orange — 75–95% full
- ■ Red — over 95% full
Frequently Asked Questions
How do I calculate the volume of a cylindrical water tank?
Measure the diameter and height of the tank in cm or inches. Select Vertical Cylinder, enter the dimensions, and click Calculate. For a 100 cm diameter tank that is 150 cm tall, the volume is π × 50² × 150 ≈ 1,178,097 cm³ ≈ 1,178 liters ≈ 311 US gallons.
What is the formula for a rectangular tank?
Volume = Length × Width × Height. A tank that is 200 cm × 100 cm × 80 cm holds 1,600,000 cm³ = 1,600 liters = 423 US gallons.
How is the volume of a frustum (funnel-shaped tank) calculated?
Use the formula V = (π/3) × h × (R² + R×r + r²), where R is the bottom radius, r is the top radius, and h is the height. This handles tanks that widen or narrow from top to bottom.
Can I calculate how much liquid is currently in the tank?
Yes — enter the fill height in the optional Fill Height field. The calculator will show both the total capacity and the current fill volume, along with a percentage indicator.
What is the difference between a capsule and a regular cylinder?
A capsule has two hemispherical end caps, making its total length equal to the cylindrical body length plus one full diameter. This shape is common in pressure vessels, propane tanks, and aerosol containers.