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Water tank calculator

Calculate the capacity of a rectangular water tank.

Your result

Complete the fields and calculate.

Calculation method and formula

Internal length [m] × Internal width [m] × Fill height [m] × 1000

Understand the inputs

Internal length
Unit: m. Use a measured value or your own assumption.
Internal width
Unit: m. Use a measured value or your own assumption.
Fill height
Unit: m. Use a measured value or your own assumption.

Assumptions and limitations

Use internal dimensions or the actual fill depth. 1 m³ equals 1,000 litres. Slopes, curved shapes, fittings and material losses count only when explicitly included.

The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation.

Worked example

Illustrative values. Replace them with your own inputs for your calculation.

Internal length
2.4 m
Internal width
1.8 m
Fill height
1.6 m
Example result6,912 l

Volume: 6.91 m³.

Model revision: October 17, 2026 · How CleverCalc works

FAQ

Frequently asked questions

How does Water tank calculator work?+

Internal length [m] × Internal width [m] × Fill height [m] × 1000. Use internal dimensions or the actual fill depth. 1 m³ equals 1,000 litres. Slopes, curved shapes, fittings and material losses count only when explicitly included.

What assumptions should I consider for this result?+

Use internal dimensions or the actual fill depth. 1 m³ equals 1,000 litres. Slopes, curved shapes, fittings and material losses count only when explicitly included. The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation.

How accurate is the result?+

The formula uses the specified units. Displayed numbers are rounded; whole packs, item counts and full time periods may also be rounded within the calculation. Prices, measurements and model assumptions determine how well the result represents your situation.

Is this calculator free?+

Yes. Calculations and PDF export work without an account or registration.

What happens to my inputs?+

Calculations run in your browser. Results are saved locally only when you add them to My results; favourites and history are also local. Shared links contain your values. The currency tool requests the selected currencies from its rate provider without sending your amount.

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