Pipe Volume Calculator
Find out exactly how much fluid a section of pipe can hold. Enter the outer diameter, wall thickness and pipe length to get the internal volume in litres, cubic metres and US gallons.
Length unit
Diameter unit
Volume of fluid the pipe can hold
63.62 L
internal volume- 1
Inner diameter
100 − 2 × 5 mm = 90 mm - 2
Internal volume (m³)
π × (0.045)² × 10 m = 0.063617 m³π × inner_radius² × length — standard cylinder formula applied to the bore. - 3
Convert to litres
0.063617 m³ × 1 000 = 63.617
How does this calculator work?
Pipe internal volume V = π (D_inner/2)² × L, where D_inner = outer diameter − 2 × wall thickness. Enter outer diameter, wall thickness and pipe length (any unit) and get the internal fluid volume in litres, m³ and US gallons instantly.
Formula
How this is calculated
A pipe is a hollow cylinder: the fluid-carrying volume is the bore — the space inside the pipe wall. The inner diameter equals the outer diameter minus twice the wall thickness. The internal volume is then the standard cylinder formula π r² L applied to the inner radius and the pipe length.
All inputs are converted to metres before the calculation. The calculator also reports the volume in litres (1 m³ = 1 000 L) and US gallons (1 m³ ≈ 264.172 gal), and shows the material volume of the pipe wall (useful when estimating flushing volume vs. actual fill volume).
Common use cases include sizing an expansion vessel, calculating the water volume in a heating circuit, estimating drain-down time, or filling a fire-suppression system. Remember that valves, fittings and scale build-up reduce the true volume slightly.
Frequently asked questions
Check the pipe label or manufacturer specification sheet. Metric pipes (e.g. ISO 4427) stamp the outer diameter and SDR or PN rating from which you can derive wall thickness. Imperial pipes use nominal sizes — look up the relevant schedule table for actual OD and wall thickness.
No — this calculator is for circular pipes only (hollow cylinders). For rectangular or oval cross-sections use the appropriate area formula (width × height for rectangles, π a b for ellipses) and multiply by length.
Add up the pipe volumes for every segment (different diameters and lengths), then add the volumes of the boiler heat exchanger, radiators and expansion vessel. This calculator handles one segment at a time.
Also known as
TG we-Calculate Editorial Team. (2026). Pipe Volume Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/pipe-volume-calculator
TG we-Calculate Editorial Team. "Pipe Volume Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/pipe-volume-calculator.
TG we-Calculate Editorial Team, "Pipe Volume Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/pipe-volume-calculator
@misc{wecalculate_pipe_volume_calculator, title = {Pipe Volume Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/pipe-volume-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?