Water Tank Capacity Calculator
पानी ट्यांकी क्षमता
Calculate water tank capacity in litres, cubic metres and cubic feet from rectangular or cylindrical dimensions.
Find how many litres a water tank holds. Enter the dimensions of a rectangular or cylindrical tank and the calculator gives the capacity in litres, cubic metres and cubic feet, along with the usable volume at your fill level.
- Volume
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- Volume
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- Capacity in litres
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- Usable at fill level
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About the water tank capacity calculator
This calculator works out how much water a tank can hold from its dimensions. Enter the size of a rectangular tank (length × width × height) or a cylindrical tank (diameter × height), choose the unit, and the tool reports the volume in litres, cubic metres and cubic feet — plus the usable volume at your chosen fill level.
Rectangular vs cylindrical tanks
A rectangular tank's volume is length × width × height. A cylindrical tank's volume is π × (diameter ÷ 2)² × height. Both are exact geometric formulas, so the result is as accurate as the dimensions you measure. Measure inside dimensions if you can, and remember that the wall thickness of a plastic or concrete tank reduces the true capacity a little.
Why the fill level matters
A tank is rarely filled to the brim. An overhead tank with a float valve typically runs at about 90–95% of its nominal size, and an underground tank is often kept lower for safety. Use the fill level to see the realistic usable volume rather than the theoretical maximum — but size your tank on the total capacity.
Choosing a tank size
A common rule of thumb is 100–150 litres of storage per person per day for a household with a normal supply, more if supply is intermittent. Multiply your daily requirement by the number of days you want to store, then round up to the nearest standard tank size (500 L, 1,000 L, 2,000 L and so on).