Case 1
- Tank shape
- Vertical cylinder
- Measurement unit
- feet
- Diameter
- 6
- Height
- 8
- Length
- 4
- Width
- 2
6,405.12L
Open with these valuesTank Volume Calculator
6,405.12L
Result: 6,405.12 LPick the shape first — it decides which dimensions count. A vertical cylinder uses diameter and height, a horizontal one diameter and length, a box length, width and height, a capsule diameter and its straight middle. A 6 ft by 8 ft upright cylinder holds 6,405 litres, about 1,692 US gallons.
Worked examples
Case 2
- Tank shape
- Horizontal cylinder
- Measurement unit
- metres
- Diameter
- 2
- Height
- 8
- Length
- 5
- Width
- 2
15,707.96L
Open with these valuesCase 3
- Tank shape
- Rectangular (box)
- Measurement unit
- metres
- Diameter
- 6
- Height
- 1.5
- Length
- 2
- Width
- 1
3,000.00L
Open with these valuesHow it's calculated
cylinder: V = π × (d ÷ 2)² × span; box: V = l × w × h
- StepChoose the shape — it decides which fields are read.
- StepChoose the unit you measured every dimension in.
- StepEnter the dimensions that shape needs; the others are ignored.
- ResultRead the full capacity in litres.
Reference table
| Shape | Dimensions | US gal | Litres |
|---|---|---|---|
| Vertical cylinder | 6 ft across, 8 ft tall | 1692.05 | 6405.12 |
| Horizontal cylinder | 2 m across, 5 m long | 4149.60 | 15707.96 |
| Rectangular | 2 m × 1 m × 1.5 m | 792.52 | 3000.00 |
| Capsule | 2 m across, 4 m straight | 4426.25 | 16755.16 |
| Vertical cylinder | 1 m across, 2 m tall | 414.96 | 1570.80 |
Questions
Which dimensions do I need to enter?
It depends on the shape. A vertical cylinder needs diameter and height, a horizontal cylinder diameter and length, a rectangular tank length, width and height, and a capsule the diameter plus the length of its straight middle section. Fields the shape does not use are ignored.
Does a horizontal tank hold less than a vertical one?
Not when it is full — orientation does not change total capacity, only how a partial fill level behaves. A horizontal cylinder of the same diameter and length holds exactly the same litres as an upright one.
How do I convert the litres to gallons?
One US gallon is 3.785412 litres and one imperial gallon is 4.54609 litres, so divide by 3.785 or by 4.546. The two gallons differ by about 20 %, so always check which one a specification means.
What is a capsule tank?
A horizontal cylinder capped with a hemisphere at each end, giving it a pill shape. It is common for propane and pressure vessels because rounded ends handle pressure better than flat ones. Its volume is the straight section plus one full sphere.
Can I mix feet and inches?
No — enter every dimension in one unit and let the calculator convert. A tank measured as 6 ft 6 in becomes 6.5 ft or 78 in before you type it.
Is this the usable capacity?
It is the full geometric capacity. Real tanks lose a little to wall thickness, fittings and dished ends, and most are filled only to about 80 to 90 % to leave room for expansion and venting.
Sources and last check
Information, not professional advice.