Pipe Volume Calculator
Calculate the water volume held inside a pipe of a given size and length.
Find how much water a length of pipe holds — handy for purging, chlorinating or sizing systems.
The math behind it
A pipe is a thin cylinder: volume = π × radius² × length.
The inner diameter (in inches) is halved and converted to feet.
Worked example
2 in inner diameter, 50 ft long → π × (0.0833)² × 50 = 1.09 ft³ ≈ 8.16 gallons.
FAQ
Inner or outer diameter?
Use the inner diameter — that's the space water actually fills.