📖 How To Use
How to Use This Spherical Tank Volume Calculator
Calculating the exact capacity of a spherical water tank takes just seconds:
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Choose your input type
Select "Enter Diameter" if you know the full width of the sphere from one side to the other. Select "Enter Radius" if you know the distance from the centre to the edge — exactly half the diameter.
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Enter your measurement
Type the diameter or radius value. Always measure the internal dimension for accurate water storage capacity. External measurements include wall thickness and will overstate the actual volume.
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Select your unit
Choose ft, in, cm, m, or mm from the dropdown. The calculator converts everything internally to centimetres before applying the formula.
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Hit Calculate
Results appear instantly — volume in litres, US gallons, UK gallons, cubic metres, cubic feet, and the water weight in kg and lbs. Copy or print with one click.
Tip: Spherical tanks are often specified by their nominal diameter on the product label. This may be the external diameter. Subtract twice the wall thickness (typically 5–15 mm for plastic, up to 50 mm for steel) to get the internal diameter before calculating.
📐 The Formula
Spherical Tank Volume Formula
The volume of a perfect sphere is calculated using the standard sphere volume formula from Euclidean geometry:
V = (4/3) × π × r³
Where r = radius (half the diameter)
If you know the diameter (d):
V = (π/6) × d³
Litres (cm inputs): V (L) = ((4/3) × π × r³) ÷ 1,000
Cubic metres (m inputs): V (m³) = (4/3) × π × r³
This calculator converts your input to centimetres first, applies the sphere formula, then converts the result to all standard volume units simultaneously. π is computed to full floating-point precision.
Step-by-Step Worked Example
Suppose you have a spherical tank with a 120 cm diameter (60 cm radius):
r = 60 cm
V = (4/3) × π × 60³
V = (4/3) × 3.14159 × 216,000
V = 904,779 cm³
V = 904.8 litres ≈ 239 US gallons
Unit Conversion Reference
| Unit | Equals Litres | From Litres |
|---|
| 1 Litre (L) | 1 L | × 1 |
| 1 Cubic Metre (m³) | 1,000 L | ÷ 1,000 |
| 1 US Gallon | 3.785 L | ÷ 3.785 |
| 1 UK Gallon | 4.546 L | ÷ 4.546 |
| 1 Cubic Foot (ft³) | 28.317 L | ÷ 28.317 |
| 1 Cubic Inch (in³) | 0.01639 L | × 61.024 |
Water Weight
1 litre of fresh water = 1 kg (or 2.2046 lbs). This is the standard used for structural load calculations worldwide.
Weight (kg) = Volume (litres) × 1
Weight (lbs) = Volume (litres) × 2.2046
📏 Reference Data
Common Spherical Tank Sizes & Volumes
Below are typical spherical tank diameters and their calculated volumes. Use these as a quick reference when comparing options:
| Diameter | Radius | Litres | US Gallons | UK Gallons | Full Weight |
|---|
| 50 cm | 25 cm | 65.4 | 17.3 | 14.4 | 65 kg |
| 80 cm | 40 cm | 268.1 | 70.8 | 59.0 | 268 kg |
| 1.0 m | 50 cm | 523.6 | 138.3 | 115.1 | 524 kg |
| 1.2 m | 60 cm | 904.8 | 238.9 | 198.9 | 905 kg |
| 1.5 m | 75 cm | 1,767.1 | 466.7 | 388.5 | 1,767 kg |
| 2.0 m | 100 cm | 4,188.8 | 1,106.4 | 920.9 | 4,189 kg |
| 2.5 m | 125 cm | 8,181.2 | 2,161.0 | 1,798.8 | 8,181 kg |
| 3.0 m | 150 cm | 14,137.2 | 3,733.5 | 3,108.1 | 14,137 kg |
Note: All volumes calculated using V = (4/3) × π × r³ with r in cm, divided by 1,000 for litres. Always verify against your specific tank's internal dimensions.
🌐 Use Cases
When Do You Need a Spherical Water Tank?
Spherical tanks are a specialized but important tank geometry. Here's when this calculator is most useful:
🏭
Industrial & Chemical Storage
Spherical tanks distribute internal pressure uniformly — ideal for storing pressurized water, gases, and chemicals at elevated pressures.
🏗️
Elevated Water Towers
Municipal water towers often use a spherical or spheroid shape to maximize storage at height while minimizing the structural footprint.
🚢
Marine & Offshore
Spherical pressure vessels are used on LNG tankers and offshore platforms where structural strength and minimal weight matter.
🌱
Decorative & Garden
Ball-shaped garden water features and small spherical cisterns need precise volume calculations for pump sizing and water treatment dosing.
For household use, if you're sizing a spherical water feature or a compact rooftop sphere tank, this calculator gives the exact litres and gallons in one click, helping you pair it correctly with your pump size and chlorine dosage.
❓ FAQ
Frequently Asked Questions
How do I calculate the volume of a spherical water tank?
Use the formula V = (4/3) × π × r³, where r is the radius (half the diameter). To get litres from centimetre inputs, divide the result by 1,000. This calculator does all of that automatically — just enter your diameter or radius and hit Calculate.
Should I enter diameter or radius for a sphere tank calculator?
Either works — just toggle the input mode to match what you have. Diameter is the full width from one side of the sphere to the other. Radius is exactly half of that. If your tank's spec sheet lists the nominal diameter (most do), use the Diameter mode.
What is the formula for spherical tank volume?
The standard formula is V = (4/3) × π × r³. If you know the diameter instead of the radius, the equivalent formula is V = (π/6) × d³. Both give the same result. This calculator uses full floating-point π for maximum accuracy.
How many litres does a 1-metre diameter sphere hold?
A perfect sphere with a 1-metre (100 cm) diameter holds approximately 523.6 litres — or about 138 US gallons. The radius is 50 cm, and V = (4/3) × π × 50³ ÷ 1,000 = 523.6 L.
How heavy is a full spherical water tank?
Water weighs 1 kg per litre. A spherical tank holding 1,000 litres contains 1,000 kg of water. Add the weight of the tank shell (steel sphere shells can be 100–500 kg depending on diameter and wall thickness). Always verify that your support structure can handle the combined load before filling.
Why are some water towers spherical?
A sphere is the shape that encloses the maximum volume for a given surface area. It also distributes internal pressure evenly across its surface — meaning no stress concentration at corners or edges. For elevated water storage, where hydrostatic pressure is significant, a sphere requires less material than a cylinder of equal volume, reducing both cost and weight on the support tower.
Can this calculator be used for partially filled spheres?
This calculator computes full-sphere volume. Partial-fill calculations for a sphere (a spherical cap) require a more complex formula: V = (π × h² / 3) × (3r − h), where h is the height of the water level. For partial-fill needs, the formula is non-trivial — use the result here as your 100% capacity baseline and multiply by your fill fraction as an approximation for shallow fill levels.
How does a spherical tank compare to a cylindrical tank of the same volume?
A sphere uses the least surface area of any shape for a given volume — about 20% less surface area than an equivalent-volume cylinder. This means less material cost and less heat exchange with the environment. However, spherical tanks are harder to manufacture and install than cylindrical ones, making them more common in industrial and municipal settings than in residential use. Use our Cylindrical Tank Volume Calculator to compare.