Pipe Volume Calculator
Pick a PVC size or enter the inside diameter and the length to get the water in the pipe in gallons and litres, and gallons per foot.
How to use the Pipe volume calculator
- Under “What pipe is it?”, choose PVC Schedule 40, PVC Schedule 80, or one of the two options for any other pipe: inside diameter, or outside diameter and wall.
- For PVC, pick the nominal pipe size, for example 2 in. For other pipe or hose, enter the inside diameter, or the outside diameter and the wall thickness, and choose in, mm or cm.
- Enter the pipe length and choose ft, m, in or cm.
- Read the water volume in US gallons and litres, then gallons per foot, litres per metre and the weight of the water.
- To find a fill or flush time, open More options and enter a flow rate in gpm, L/min or m³/h.
- Open “How it was calculated” under the result to see the inside diameter used and the arithmetic.
- Use a preset button above the form to load a typical case: 2 in PVC at 100 ft, 4 in PVC at 50 m, a 5/8 in garden hose, or a 28 mm tube.
Under the result, two tables list the water in 100 ft of every PVC Schedule 40 and 80 size. Click “Reset” to restore the starting example. Copy result, Copy link and Print / save as PDF are covered in the FAQ below.
How do you calculate the volume of water in a pipe?
A pipe is a cylinder, and the water fills its inside. Volume = π ÷ 4 × inside diameter² × length. The inside diameter is the size of the hole, not the outside of the pipe. Convert to US gallons using 1 ft³ = 7.4805 gal (231 in³ per gallon).
Worked example: 2 in PVC Schedule 40 has an inside diameter of 2.049 in. That is 0.17130 gal per foot, so 100 ft of it holds 17.13 gal (64.8 L) and the water weighs about 143 lb at 8.34 lb per gallon.
How many gallons are in a foot of pipe?
It depends on the inside diameter only. Gallons per foot for PVC Schedule 40 are about 0.0268 for 3/4 in, 0.0435 for 1 in, 0.1713 for 2 in and 0.6521 for 4 in; the page lists every size. Doubling the diameter multiplies the volume by four, because the diameter is squared. Schedule 80 pipe has thicker walls and a smaller bore than Schedule 40 of the same nominal size, so it holds less.
Why is the inside diameter not the same as the nominal size?
Nominal pipe size is a trade name. A 2 in PVC pipe has an outside diameter of 2.375 in and, in Schedule 40, an inside diameter of 2.049 in. The calculator uses the inside diameters printed on the JM Eagle data sheet (ASTM D1785 and D2665). Other makers’ pipe can differ by a few thousandths of an inch. Copper, PEX and hose are sized differently, so for those enter the inside diameter, or the outside diameter and wall.
Sources
Checked October 2026: PVC Schedule 40 and 80 inside diameters from the JM Eagle Solvent Weld Schedule Series data sheet (revised 3/2/2012). Volume is the volume of a cylinder; 1 US gal = 231 in³ and 1 ft³ = 7.4805 gal. Water at 8.34 lb per US gal.
For estimation; verify critical designs against the applicable standard.
Worked examples
| Input | Result |
|---|---|
| 2 in PVC Schedule 40, 100 ft long | 17.13 gal (64.84 L), 0.1713 gal/ft |
| 4 in PVC Schedule 40, 50 m long | 107 gal (405 L), 0.6521 gal/ft |
| pipe with 0.625 in inside diameter, 50 ft long | 0.7969 gal (3.016 L), 0.01594 gal/ft |
| pipe with 0.9843 in inside diameter, 30 m long | 3.89 gal (14.73 L), 0.03952 gal/ft |
Calculated by the tool above with these values.
Frequently asked questions
Can I use the results in commercial projects or client reports?
Yes. You can use the results in commercial work, including quotes, design notes, reports and client projects, without attribution. The page also notes under each result: “For estimation; verify critical designs against the applicable standard.”
Is the calculator free, and is anything I type uploaded?
Yes, the calculator is free. Everything is calculated in your browser, so nothing you type is uploaded. There is no account or sign-up.
Can I print or share a calculation?
Yes. Print / save as PDF prints a one-page record with your inputs, results, calculation steps and the date. Copy link copies the page address, which stores every input in the ?s= part of the URL, so the same calculation reopens later or can be sent to a colleague. Copy result copies the result lines with a link.
Does the volume include fittings and valves?
No. The result is for the straight pipe only. Elbows, tees, valves, filters, pumps and heaters hold more water, so add them separately if you need a total for a system.
How many gallons are in 100 feet of 1 inch pipe?
For PVC Schedule 40, 1 in pipe has a 1.033 in inside diameter, so 100 ft holds 4.35 gallons (16.5 L). For a different material, enter its inside diameter and the calculator gives the volume for any length.
How long does it take to fill or flush a pipe?
Enter a flow rate under More options and the calculator divides the volume by the flow. For example, 17.13 gal at 10 gpm takes about 1 min 43 s. Real times differ if the flow changes with pressure or air is trapped in the line.
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