acalculator

What is the pipe volume?

Type the inside diameter of the pipe, or its outside diameter and wall thickness, and its length. The pipe volume calculator gives the water it holds in gallons, liters, cubic feet and cubic meters, and what that water weighs.

Your numbers

Units
I know the
US gallons
16.32

The pipes hold 16.32 US gallons (136.1 lb of water): 1 × 100 ft with an inside of 2 in.

Liters
61.78
Cubic feet
2.182
Cubic meters
0.0618
Water weight (lb)
136.1
Water weight (kg)
61.7
Gallons per foot
0.1632
Liters per meter
2.0268
Inner diameter (in)
2
Inner diameter (mm)
50.8

US gallons: 16.32. The pipes hold 16.32 US gallons (136.1 lb of water): 1 × 100 ft with an inside of 2 in.

How to calculate

Works out how much water a pipe holds from its inner diameter (or outer diameter and wall) and length, in gallons, liters, cubic feet and cubic meters, with the weight of the water.

Example with the default inputs (I know the Inner diameter, Inner diameter 2 in, Pipe length 100 ft, Number of pipes 1): The pipes hold 16.32 US gallons (136.1 lb of water): 1 × 100 ft with an inside of 2 in.

Method: V = π × (d ÷ 2)² × L × n, with d the inner diameter (or outer diameter − 2 × wall); water weight = V × 999.07 kg/m³.

  • The pipe is a straight round tube, full of water. Fittings, bends and valves are not counted.
  • Water weighs 0.99907 g/cm³ (62.366 lb/ft³) at 60 °F (15.6 °C); warmer water weighs a little less.
  • 1 US gallon is 231 in³ (3.785411784 L).

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. I know the Inner diameter, Inner diameter 2 in, Pipe length 100 ft, Number of pipes 1 gives US gallons 16.319962, Gallons per foot 0.1632, Cubic feet 2.181662.Source: OpenStax, Prealgebra 2e, §9.6 Solve Geometry Applications: Volume and Surface Area (V = πr²h). https://openstax.org/books/prealgebra-2e/pages/9-6-solve-geometry-applications-volume-and-surface-area; NIST Handbook 44, Appendix C, General Tables of Units of Measurement (1 in = 2.54 cm; 1 US gallon = 231 in³; 1 lb = 0.45359237 kg). https://www.nist.gov/pml/owm/nist-handbook-44-current-edition
  2. I know the Inner diameter, Inner diameter 3.937 in, Pipe length 32.81 ft, Number of pipes 3 gives Cubic meters 0.235619, Liters 235.619449, Water weight (kg) 235.400323.Source: OpenStax, Prealgebra 2e, §9.6 Solve Geometry Applications: Volume and Surface Area (V = πr²h). https://openstax.org/books/prealgebra-2e/pages/9-6-solve-geometry-applications-volume-and-surface-area; USGS Water Science School, Water Density (0.99907 g/cm³ at 60 °F). https://www.usgs.gov/special-topics/water-science-school/science/water-density
  3. I know the Outer diameter and wall, Outer diameter 2.375 in, Wall thickness 0.154 in, Pipe length 10 ft, Number of pipes 1 gives Inner diameter (in) 2.067, US gallons 1.743171.Source: OpenStax, Prealgebra 2e, §9.6 Solve Geometry Applications: Volume and Surface Area (V = πr²h). https://openstax.org/books/prealgebra-2e/pages/9-6-solve-geometry-applications-volume-and-surface-area; NIST Handbook 44, Appendix C, General Tables of Units of Measurement (1 in = 2.54 cm; 1 US gallon = 231 in³; 1 lb = 0.45359237 kg). https://www.nist.gov/pml/owm/nist-handbook-44-current-edition

How it works

The inside of a pipe is a cylinder. With inner diameter d, length L and n pipes:

  • Inner diameter: the typed inner diameter, or d = outer diameter − 2 × wall thickness.
  • Volume: V = π × (d ÷ 2)² × L × n, in cubic meters inside the page.
  • US gallons: V ÷ 0.003785411784 (1 gallon = 231 in³). Liters: V × 1,000. Cubic feet: V ÷ 0.3048³. Cubic meters: V.
  • Water weight: V × 999.07 kg/m³ (water at 60 °F). Pounds: kilograms ÷ 0.45359237.
  • Inner diameter shown: d ÷ 0.0254 in inches and d × 1,000 in millimeters.
  • Per foot and per meter: the volume of 0.3048 m (in gallons) and of 1 m (in liters) of one pipe.

Rules

  • Each diameter and the wall are more than 0 and at most 10 m. The length is more than 0 and at most 10,000 km. The number of pipes is a whole number from 1 to 1,000,000.
  • With the outer diameter, two walls must be thinner than the outer diameter; otherwise there is no answer. Two walls equal to the outer diameter typed in another unit (within 10⁻¹² of it) count as equal.
  • The pipe is full and straight. Fittings, bends and valves are not counted.

Output format. Gallons and liters show 2 decimals, cubic feet 3, cubic meters 4, weights 1, per foot and per meter 4, the inner diameter in inches 4 and in millimeters (d × 1,000) 2. Each is a double-precision number.

Worked examples by hand

2 in inside, 100 ft. π × (2 ÷ 2)² × 1,200 in = 3,769.91 in³. 3,769.91 ÷ 231 = 16.32 gallons, or 0.1632 gallons per foot. In cubic feet: 3,769.91 ÷ 1,728 = 2.182 ft³.

Three pipes, 100 mm inside, 10 m each. π × 0.05² × 10 × 3 = 0.235619 m³ = 235.62 liters. The water weighs 0.235619 × 999.07 = 235.40 kg.

2.375 in outside with a 0.154 in wall, 10 ft. Inside 2.375 − 2 × 0.154 = 2.067 in. π × 1.0335² × 120 = 402.67 in³ ÷ 231 = 1.7432 gallons.

Other questions people ask

How do I calculate the volume of a pipe?

A pipe’s inside is a cylinder: V = π × (d ÷ 2)² × L, with d the inside diameter and L the length. 100 ft of pipe 2 in across inside holds π × 1² × 1,200 = 3,769.9 in³, which is 3,769.9 ÷ 231 = 16.32 US gallons.

Should I use the inside or the outside diameter?

The inside diameter, because only the inside holds water. If you know the outside diameter and the wall thickness, the inside is the outside minus two walls. A pipe 2.375 in across outside with a 0.154 in wall is 2.067 in across inside.

How many gallons are in one foot of pipe?

One foot of pipe holds π × (d ÷ 2)² × 12 ÷ 231 gallons, with d in inches. That is 0.1632 gallons for a 2 in inside diameter and 0.0408 gallons for 1 in.

How much does the water in a pipe weigh?

Multiply the volume by the density of water. At 60 °F water is 0.99907 g/cm³, or 62.366 lb per cubic foot, so 16.32 gallons (2.18 ft³) weighs about 136 lb.

Does the length unit matter?

No. Type the length in feet, inches, yards, miles, meters, centimeters or kilometers, and the diameters in inches, feet, millimeters, centimeters or meters. The page converts them before it multiplies.

Are fittings and bends counted?

No. The page treats the pipe as one straight tube. Elbows, tees and valves hold a little more; add their length if you know it.