How it’s calculated
- Volume = π ÷ 4 × ID² × length
- Gallons = ft³ × 7.4805
- Weight = gallons × 8.34 lb
Worked example
100 ft of ¾ in type L copper (0.785 in ID).
Inputs
- Pipe inside diameter
- 0.785 in
- Pipe length
- 100 ft
Results
- Water volume
- 2.51 gal
- Weight of water
- 21 lb
- Gallons per foot
- 0.0251 gal/ft
Assumptions and limits
- Water at about 60 °F.
Verify the result against the applicable local code, adopted code edition, manufacturer instructions and project requirements. See our methodology.
Questions
How much water is in 100 feet of ¾ inch pipe?
About 2.5 gallons for ¾ in type L copper, which is why hot water takes a while to arrive at distant fixtures.
How much does water weigh?
About 8.34 lb per US gallon.