Tank Size Calculator
Calculate the volume of your tank for aquariums, fuel storage, water tanks, and more. Enter your tank shape and dimensions to get accurate volume measurements in multiple units.
How the tank size calculator works
This calculator determines the volume of a tank based on its shape and dimensions. Select from rectangular, cylindrical, spherical, conical, or hemispherical tanks. Enter the required dimensions — the calculator instantly shows the volume in litres, US gallons, Imperial gallons, cubic feet and cubic metres, plus the weight of water when full.
Perfect for aquarium sizing, fuel tank capacity, water storage planning, and industrial tank volume estimation.
Step 1: Tank Shape & Dimensions
Measuring Tips
For best accuracy, measure the internal dimensions of your tank. For cylindrical tanks, measure the diameter (not radius) — the calculator will convert it. Always use the same unit for all measurements.
Step 2: Units & Preferences
Water Weight Reference
Fresh water weighs 1 kg per litre (8.34 lbs per US gallon). Saltwater is about 2.5% heavier. Use this to estimate the total weight of your filled tank.
Tank Volume Results
Total Tank Volume
Unit Comparison
| Unit | Volume | Equivalent | Water Weight |
|---|
Volume Formula
Cylindrical Tank
V = π × r² × h
Shape Reference
Common Tank Shapes
Rectangular: V = l × w × h | Cylindrical: V = π × r² × h | Spherical: V = 4/3 × π × r³ | Conical: V = 1/3 × π × r² × h | Hemispherical: V = 2/3 × π × r³
Frequently Asked Questions
How do you calculate tank volume?
Tank volume depends on the shape. For a rectangular tank: volume = length × width × height. For a cylindrical tank: volume = π × radius² × height. For a spherical tank: volume = 4/3 × π × radius³. This calculator handles all these shapes automatically.
How many litres in a gallon?
There are approximately 3.785 litres in a US gallon and 4.546 litres in an Imperial (UK) gallon. This calculator uses US gallons by default but you can switch to Imperial gallons.
How much water weight is in a full tank?
Water weighs about 1 kg per litre (or 8.34 lbs per US gallon). So a 100-litre tank holds about 100 kg of water (220 lbs). This calculator shows water weight for your tank size.
What is the formula for a cylindrical tank?
The volume of a cylindrical tank is V = π × r² × h, where r is the radius (half the diameter) and h is the height. This calculator uses that formula to give you the volume in your chosen units.
How do you measure tank dimensions?
Measure the internal dimensions for accurate capacity. For rectangular tanks: length, width and height. For cylindrical tanks: diameter (or radius) and height. Always use the same unit (cm, inches, etc.) for all measurements.
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