Pipe volume calculator
Water in a straight run of pipe from the inside diameter of the size you pick and the length you enter, in US gallons and litres, with the weight of that water. It runs in your browser. Nothing you enter is sent anywhere.
The calculator could not start in this browser, so no form is shown. Try a current browser. The formula and sources are on the methodology page.
Result
Volumes are shown to three significant digits and weights to the nearest tenth. The computation uses the unrounded numbers.
Show the math
area = π ÷ 4 × ID to the power 2
volume = area × length
gallons = volume in cubic inches ÷ 231
litres = gallons × 3.785412
weight = gallons × 8.34 lb, or litres × 0.99975 kg
ID is the inside diameter in inches and the length is in inches. The 231 cubic inches per gallon and the litres per gallon follow from NIST SP 811 Appendix B.8. The weights are for water at 50°F from the USGS density table. Where each inside diameter comes from is on the methodology page.
What this tool does not do
- Fittings and valves. Their volume is not added.
- Partly filled or sloped drains, and tube that is not round.
- CPVC, ABS, cast iron, copper DWV and ACR tube, steel above 4 in. or below 1/2 in., PVC above 6 in.
- Hot water weight. The tool weighs cold water and says so.
- Pressure, flow, expansion tanks and anything else about the water in the pipe.
The sources of every inside diameter, the constants and the open questions are on the methodology page. Sources were last checked on October 4, 2026.