Pipe Volume Calculator

Find how much water a length of pipe holds — useful for flushing, winterizing and hot-water wait time estimates.

Water in pipe

2.29 gal

  • Gallons per 100 ft2.29 gal
  • Liters8.7 L
  • Weight of water19.1 lb

Estimates only. Round up when you order, and confirm structural details with your local building code.

How to use it

  1. Enter the inside diameter.
  2. Enter the pipe length.

The formula

Gallons = π × (inside diameter ÷ 2)² × length × 7.48

Worked example

Inside diameter0.75 in
Pipe length100 ft

Result

Water in pipe2.29 gal
Gallons per 100 ft2.29 gal
Liters8.7 L
Weight of water19.1 lb

Tips before you order

  • Nominal pipe size isn't the inside diameter — check the pipe's schedule or type (e.g. Type L copper, PEX).

Questions

How much water is in 100 ft of ¾ in pipe?

About 2.3 gallons using a 0.75 in inside diameter.