Water Tank Calculator
Calculate water tank capacity for cylindrical or rectangular tanks and estimate fill time.
How it works
- 1Select the tank shape and enter its dimensions in metric or imperial.
- 2Enter the fill flow rate delivered by your pump or pipe.
- 3The calculator shows capacity in litres or gallons and the estimated time to fill.
Use cases
- Sizing a domestic rainwater or storage tank.
- Estimating how long a pump must run to fill a reservoir.
- Checking a tank has enough capacity for emergency water supply.
Frequently asked questions
How is tank volume calculated?
A cylinder uses V = π/4·d²·h; a rectangular tank uses V = l·w·h. Results are in m³ — multiply by 1000 for litres.
How is fill time calculated?
Fill time (s) = volume (m³) ÷ flow rate (m³/s). A 2.83 m³ tank at 0.5 L/s takes about 5660 s ≈ 94 minutes.
What is 1 m³ in litres and gallons?
1 m³ = 1000 litres ≈ 264.2 US gallons. The result is shown in litres (metric) or gallons (imperial).
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