Tank Volume Calculator
Calculate the capacity of cylindrical and rectangular water tanks in litres, cubic metres and water weight. Perfect for overhead tanks.
Tank capacity
2,135 L
Volume
2.14 m³
75.4 cubic feet
Water weight
2,135 kg
Full tank, water at 4 °C
Cylindrical: π × r² × h. Rectangular: length × width × depth. 1 m³ = 1,000 L and 1 L of water weighs 1 kg.
Tank Volume Calculator on True Calculator gives you an instant, accurate answer with no sign-up and no app install. Calculate the capacity of cylindrical and rectangular water tanks in litres, cubic metres and water weight. Perfect for overhead tanks. Every result shows the formula and a worked example so you can verify the calculation yourself, and all values are computed in your own browser — your numbers never leave your device.
Popular uses: tank volume calculator · water tank capacity calculator · tank capacity in litres
Reviewed by the True Calculator team · Last updated: August 2026
How We Calculate
This calculator uses standard construction and engineering formulas verified by our team. All calculations are performed instantly in your browser using JavaScript — no data is sent to any server.
Material quantities follow common construction practice and standard mix ratios. Always confirm with a professional before purchasing materials.
When to Use This Calculator
Every Indian household that survives on municipal or tanker supply has faced the same decision: what size overhead tank fits the daily routine and the roof? This calculator answers it from simple feet measurements — the units tank sellers in India use. Plumbers use it to match tank size with pump delivery rate, civil engineers need the full-tank weight to design slabs and supports, and aquaculture and factory buyers check cylindrical tank capacities before ordering. Since 1 m³ is 1,000 litres and 1 litre of water weighs 1 kg, the volume result doubles as a weight estimate, giving both the capacity and the structural load in one step.
How to Use This Calculator
- Step 1: Choose the tank shape — cylindrical or rectangular.
- Step 2: For a cylindrical tank, enter the diameter and height in feet.
- Step 3: For a rectangular tank, enter length, width and depth in feet.
- Step 4: Read the capacity in litres, cubic metres, cubic feet and the water weight.
Worked Example
A family in Pune is choosing an overhead tank for their flat. A cylindrical tank 4 ft in diameter and 6 ft tall holds π × (2)² × 6 = 75.4 cubic feet, which converts to 2,135 litres. A rectangular tank measuring 4 ft × 4 ft × 4 ft holds 64 cubic feet, or 1,812 litres. Either way, the full-tank water weight equals the litres in kilograms — 2,135 kg in the first case — which the structural engineer needs to check the roof slab can carry it.
Tips and Common Mistakes
- •Tip 1: Measure the inside of the tank, not the outside, since walls reduce the true capacity.
- •Tip 2: For a family of four, 1,000–2,000 litres usually covers two days of usage between supplies.
- •Tip 3: The water weight equals the litre capacity in kg — a full 2,000 L tank loads the roof by 2,000 kg.
- ✗Mistake 1: Using the outer dimensions — tank walls and fittings eat into the actual capacity.
- ✗Mistake 2: Forgetting that the roof must carry the full weight; a big tank on a thin slab is a structural risk.
Frequently Asked Questions
How do I find my water tank capacity in litres?
Measure the inside dimensions of the tank and enter them here. A cylindrical tank 4 ft wide and 6 ft tall holds about 2,135 litres; a 4 × 4 × 4 ft rectangular tank holds about 1,812 litres.
Which tank size should I choose for my home?
A typical Indian family of four uses roughly 1,000–1,500 litres over two days, so a 1,000–2,000 litre overhead tank is common. Factor in daily usage and supply frequency.
Does water weight matter for the roof?
Very much. 1 litre of water weighs 1 kg, so a full 2,000 litre tank adds 2,000 kg to your roof structure — the builder must account for this dead load.
Why use feet instead of metres?
Tank sizes in India are usually quoted in feet or inches — a '4 by 6' cylindrical tank, for example. The calculator accepts feet and converts internally to litres.
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