Pipe volume
Useful for fill, drain-down and flush volume. Not a pipe schedule.
Method
V = πd²L/4. Worked case: 100 mm internal diameter, 40 m, is 0.314 m³ (314 litres).
What to write beside the result
A review can only check this figure if the inputs sit next to it. Write the value, the unit and the assumption the form used. A diameter in millimetres and a diameter in metres are not the same reading. A force in kilonewtons divided as if it were newtons is a thousand-fold error.
The result is the arithmetic on this page. It is not a utilisation, not a selected product, and not a clause from a standard. If the number is going into a shared container, name the page, the date and the inputs. The file-name checker does not read the calculation.
Logic: how this figure is built.
How to read a pipe volume
Volume is the bore area times the length. It is the volume of fluid in a full pipe, or the volume of the bore if you are filling it. It is not a flow rate.
Length is the centre-line length, including the vertical risers if they are part of the fill. A plan length that ignores a riser under-states the volume. Bore diameter, not outside diameter, sets the area.
A partially full pipe is not this cylinder. A drain running at half depth needs a segment area. This page assumes full.
Use it for a flush volume or a fill quantity beside a model. It does not size the pipe.
- Related: pipe velocity
- pipework guide
Last checked 3 October 2026. A scenario, not a design. See methodology, standards and the disclaimer.