Tank Volume Calculator
Simple tank calculator for total volume and optional filled volume.
Use this Tank Volume Calculator to estimate the total capacity, filled volume, and fill percentage of vertical cylindrical, horizontal cylindrical, and rectangular tanks.
Tank Volume Formulas
Vertical Cylinder
Total volume = π × r² × H
Filled volume = π × r² × h
Rectangular Tank
Total volume = length × width × height
Filled volume = length × width × filled height
Horizontal Cylinder
Total volume = π × r² × length
A partially filled horizontal tank requires a circular-segment calculation because liquid volume does not increase evenly with fill height.
Segment area = r² × cos⁻¹((r − h) ÷ r) − (r − h) × √(2rh − h²)
Filled volume = segment area × tank length
Where r is radius, h is filled height, and H is full tank height.
Fill percentage = filled volume ÷ total volume × 100
Example
Suppose a vertical cylindrical tank has an internal diameter of 2 m and a height of 3 m.
Radius = 2 ÷ 2 = 1 m
Volume = π × 1² × 3
Volume ≈ 9.425 m³
Since 1 m³ equals 1,000 litres:
Capacity ≈ 9,425 litres
Important Notes
- Use internal tank dimensions whenever possible.
- Filled height should be measured from the inside bottom of the tank.
- For a horizontal cylinder, fill percentage is not normally the same as height percentage.
- Rounded or domed ends, sloped bottoms, wall thickness, baffles, fittings, sediment, and tank tilt can change actual capacity.
- For fuel, chemical, pressure, commercial, or regulated storage, use the manufacturer’s rated capacity or calibrated tank data instead of relying only on geometric volume.
Sources
- NIST — SI Units: Volume
- Wolfram MathWorld — Circular Segment