Volume Calculator
Calculate cylindrical tank volume in liters or cubic meters using radius and height
Height Calculator
Calculate cylindrical tank height from volume and radius in millimeters or meters
Weight Calculator
Calculate the weight of liquid in cylindrical tanks using volume and material density
Diameter Calculator
Calculate cylindrical tank diameter and radius from volume and height
Cylindrical Tank Diameter Calculator
Calculate cylindrical tank diameter and radius from volume and height. Get results in mm, cm, meters, or more.
Height
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Radius
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Diameter
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Volume
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Not to scale · updates live
Result
Enter height and volume to see the result.
How to find the diameter a tank needs
Start from the capacity you want and the height you've got. The tool solves for the width.
- 01
Enter the capacity you need
Type the volume and pick litres or cubic metres. Those are the only two volume units here, so convert gallons first (1 US gallon is 3.785 L).
- 02
Enter the height you can allow
This is the usable liquid height, set by a ceiling, a shed roof or a stand. Pick its unit from the dropdown: mm, cm, m, km, inches, feet or yards.
- 03
Read the radius and diameter
Both come back in the same unit as the height, from d = 2 × √(V ÷ (π × h)). For 5,000 L in 2.2 m of height, that's a diameter of 1.70 m.
Diameter needed for common capacities
Each cell is the inside diameter a cylinder needs to hold that volume at that height. It's the quickest way to see whether a tank will fit a space before you shop for one.
| Capacity | 1.0 m tall | 1.5 m tall | 2.0 m tall |
|---|---|---|---|
| 500 L | 0.80 m | 0.65 m | 0.56 m |
| 1,000 L | 1.13 m | 0.92 m | 0.80 m |
| 2,000 L | 1.60 m | 1.30 m | 1.13 m |
| 5,000 L | 2.52 m | 2.06 m | 1.78 m |
| 10,000 L | 3.57 m | 2.91 m | 2.52 m |
Because diameter grows with the square root of volume, doubling the capacity only makes the tank about 41% wider (√2 ≈ 1.414). Going from 1,000 L to 2,000 L at 1.5 m tall takes the diameter from 0.92 m to 1.30 m.
Leave room for air and walls
Tanks shouldn't be filled to the brim. Overflow pipes and inlet floats usually sit below the top, so plan on about 10% headspace. In the rainwater example, a 2.2 m tall tank with 10% kept empty has 1.98 m of liquid height. Holding 5,000 L in that needs a diameter of 1.79 m instead of 1.70 m.
The answer is also an inside diameter. Add twice the wall thickness to get the outside width, and then check it against the narrowest point it has to pass: a gate, a doorway or a stairwell. A tank that fits the plinth but not the gate is a common and expensive surprise.
When the width is the unknown
Fitting a tank under a low roof
When height is fixed by a shed or a loft, this tells you how wide the tank has to be, so you can measure the floor before you order.
Comparing tall-and-thin with short-and-wide
Try the same volume at two heights. A short, wide tank is more stable but takes floor space; a tall, narrow one does the opposite.
Sizing a custom container
Packaging and fabrication work often starts from a target volume and a height limit. The diameter is the last dimension to fix.