Pipe Volume Calculator
Calculate how much water a pipe holds. Free, fast and easy to use.
How it works
The volume of a pipe is the area of its inner cross-section multiplied by its length. Use the inner diameter, not the outer one. It is useful for filling heating systems, flushing pipes or dosing antifreeze.
Formula
V = π × (d / 2)² × L
Worked examples
- Inner diameter (mm): 16 · Length (m): 50 → Capacity: 10.053 L
- Inner diameter (mm): 26 · Length (m): 100 → Capacity: 53.093 L
Calculations run locally in your browser. Results are for information only — for engineering, electrical or financial decisions, verify the assumptions and applicable standards.
Frequently asked questions
How much water is in 1 m of pipe?
A pipe with a 20 mm inner diameter holds about 0.31 liters per meter; 16 mm holds 0.20 L/m and 26 mm about 0.53 L/m.
Why use the inner diameter?
Only the inside of the pipe holds water. Pipes are often sold by outer diameter, so subtract twice the wall thickness.