Water Tank Calculator
Calculate rectangular tank capacity in litres, US gallons and imperial gallons.
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How to use it
- Replace the examples with your measurements or exact product coverage.
- Choose the unit beside each input. Changing the unit converts the existing value.
- Choose any allowance deliberately, calculate, and check the purchase units.
Formula
Rectangular water volume = internal length × internal width × water depth.
Worked example
2 × 1 × 1 m = 2 m³ = 2,000 L ≈ 528.344 US gal.
Common mistakes and limits
Rectangular internal volume only. No allowance for freeboard unless you reduce entered water depth. Not a tank-support or structural assessment.
Do not add allowance twice. Example coverage, density and prices are illustrative, not a specification for your project.
Frequently asked questions
Can this calculate a horizontal cylindrical tank?
No. This release supports rectangular internal dimensions only.
Should I enter full tank height?
Enter the intended water depth. Reduce it to allow for freeboard and measure inside the walls.
Are my measurements sent to a server?
These calculations run in your browser. This calculator does not send the input values to our server. Normal page requests can still appear in hosting logs.
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