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.
Last updated: August 2026
How this calculator is verified
Checked by True Calculator automated test suite on
- Formula verified against a published worked example in the automated test suite
- Edge cases (zero, negative, boundary and unit-mismatch inputs) covered by unit tests
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
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.
Sources and References
- •IS 3938: Specification for Elevated Circular Water Tanks — Bureau of Indian Standards
- •1 litre = 1 kg (water at 4°C) — National Institute of Standards and Technology
Official sources are linked so you can confirm the current rate yourself. Check the linked page for the latest notification before relying on these figures.
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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