Geometry & drainage
Rectangular tank volume
- where
- tank volume (m³; the calculator shows L)
- internal length (m)
- internal width (m)
- water depth (m)
Explain this equation
Works out the volume of water in a rectangular tank or cistern. Use it for storage capacity or dosing.
L is the internal length, w the internal width and h the water depth.
Volume of a box is length × width × height. The calculator works in m³ and shows litres; 1 m³ is 1000 L.
Sense check: 1 m × 0.5 m with 0.4 m of water holds 200 L. Measured in cm, length × width × depth ÷ 1000 gives litres.
Watch out: use internal dimensions and the actual water depth, not the outside case size or full height.
Enter your values to see the result.
Good to know
Internal dimensions and water depth, not external case dimensions.
Sources
Results are arithmetic only. Worked examples are not recommended design settings. This library does not provide automatic gas pipe selection, live gas tightness tests, purging procedures, combustion acceptance limits, installation approval or commissioning certification. Manufacturer data and the applicable current method remain essential.