PVC Pipe Volume Calculator
Same volume in every unit
Fluid weight
Estimated fill / drain time
Your recent calculations (saved on this device)
| When | ID | Length | Result |
|---|
PVC is preloaded as Schedule 40. Switch to Schedule 80 for the thicker wall and smaller bore.
How to use this calculator
- Choose the unit system — US, Imperial or metric — at the top of the calculator.
- Pick the pipe type and schedule, then the nominal size, and the real inside diameter loads for you. Or choose Custom and type any bore.
- Enter the pipe length. Open Advanced to set fill level, number of identical runs, a fittings allowance, the fluid, or a flow rate.
- Press Calculate to see the volume in every unit, plus fluid weight, cross-section area and fill or drain time.
- Copy, share or print the result. Recent calculations are saved on your own device so you can reopen them later.
Tip: not sure where to start? Use the Fill example data button to load a complete worked example — a 2-inch Schedule 40 line, 50 ft long, at 10 gal/min — then adjust the numbers to match your job.
Real-world uses, with numbers
Charging a radiant-heat loop
How much water sits in a 300 ft run of ½" PEX.
≈ 2.9 US galSizing a well pressure tank
Line-fill volume in 100 ft of 1" Schedule 40.
≈ 4.5 US galFlushing a main
Water to displace in 100 ft of 4" Schedule 40.
≈ 66 gal · 250 LWater weight on hangers
Load from a full 100 ft run of 2" pipe.
≈ 145 lb · 66 kgMetric heating fill
Charge volume for 50 m of 28 mm bore.
≈ 30.8 LFuel or oil line contents
Diesel held in 20 m of 50 mm bore.
≈ 39 L · 33 kgMore questions, answered
How do I convert between gallons, litres and cubic metres?
1 US gallon = 3.785 litres; 1 Imperial gallon = 4.546 litres; 1 m³ = 1,000 litres = 264.2 US gallons. The calculator shows all of them from a single entry, so you never convert by hand.
Does the pipe material change the volume?
Only through the bore. Two pipes with the same inside diameter hold the same volume whether they are steel, PVC, copper or PEX. Material and schedule matter because they set the real inside diameter for a given nominal size.
How much does the water inside a pipe weigh?
About 8.34 lb per US gallon, or 1 kg per litre. A full 100 ft run of 2" Schedule 40 holds roughly 17.4 gallons, about 145 lb. Set the fluid in Advanced for hot water, glycol, diesel or seawater.
What if I only know the outside diameter?
Switch the diameter to OD mode and enter the wall thickness; the tool subtracts two wall thicknesses to reach the bore. For a listed standard, just pick the size and the published inside diameter loads automatically.
Can I use it for a part-full or sloped drain?
Yes for a straight, round pipe: open Advanced and set the fill level below 100%, and the volume scales with it. Truly partial gravity flow in a sloped line follows a curved free surface, so treat the part-full figure as an approximation.
Notes and derived figures
- Volume scales with the square of the bore: doubling the inside diameter roughly quadruples the capacity, while doubling the length only doubles it.
- Per-foot and per-metre capacity are constant for a given bore, so any length is a single multiplication — handy for quick field estimates.
- Nominal size is a label. A "2-inch" Schedule 40 pipe has a 2.067-inch bore; using "2" overstates the volume by more than a third.
- Fill and drain time is volume divided by flow rate. Enter a flow rate in Advanced to turn any result into a charge, flush or drain time.
Schedule 40 vs Schedule 80 PVC
PVC pipe shares the same outside diameters as steel, so a given nominal size drops straight into standard fittings. What changes with schedule is the wall: Schedule 80 has a thicker wall and therefore a smaller bore and a higher pressure rating than Schedule 40 of the same size. Because volume follows the bore squared, the difference is real — 4-inch Schedule 40 has a 4.026 in bore, while Schedule 80 is 3.826 in, holding a few percent less per foot. Select the right schedule above and the tool takes care of it.
The nominal-size trap with PVC
A "1-inch" PVC pipe is neither 1 inch on the outside nor 1 inch on the inside — the OD is 1.315 in and the Schedule 40 bore is 1.049 in. Typing "1" into a plain cylinder formula overstates the water it holds. The calculator sidesteps this by looking up the published bore whenever you choose a PVC schedule and size, and it shows you which inside diameter it used.
What PVC volume is used for
- Irrigation and sprinkler zones — line contents affect fill time and the drain-back you see after a zone shuts off.
- Pool and spa plumbing — pipe water adds to total system volume for chemical dosing.
- Pressure testing — the volume tells you how much water to add and how a leak will show up as pressure loss.
- DIY water features and aquaponics — knowing pipe contents helps balance pumps and reservoirs.
A quick PVC example
Say you have run 60 ft of 1-1/2-inch Schedule 40 PVC to a sprinkler manifold. With a bore of 1.610 in, each foot holds about 0.106 US gallons, so the run contains roughly 6.3 gallons — about 53 lb of water sitting in the line. The calculator returns that instantly, plus the litres and cubic-feet equivalents and the fill time at your zone flow rate.
Getting an accurate PVC figure
Match the schedule to the pipe you actually bought (most residential white PVC is Schedule 40; grey electrical and some pressure lines are Schedule 80). For part-full gravity drains, set a fill level below 100%. And if you are measuring an odd or salvaged pipe, switch to Custom and enter the bore you measure directly — a direct measurement always beats a lookup.
Reading and trusting your result
The result above answers most questions; this note covers how to interpret it and its limits.
What the number actually means
The headline value is the internal capacity of a round, uniform pipe running full — the fluid the bore can hold along the length you entered. Every other unit on the panel is the same physical quantity re-expressed, so you can quote whichever your paperwork needs without recalculating.
The full-pipe assumption
By default the figure assumes the pipe is completely full and perfectly cylindrical. For gravity drains and vented lines that run part full, set a fill level below 100% and the result scales with it. Bends, valves and fittings add a little capacity the straight-length model does not see — use the fittings allowance to approximate them.
Capacity reference tables & a worked example
Concrete numbers for this page, calculated the same way the tool above does — use them as a quick check or a lookup.
Schedule 40 2" pipe: volume by run length
How much a 2" Schedule 40 bore holds as the run gets longer, in US gal. The per-foot figure is constant, so any length is one multiplication away.
| Length (ft) | Volume (US gal) | Per foot |
|---|---|---|
| 10 ft | 1.74 | 0.1743 |
| 25 ft | 4.36 | 0.1743 |
| 50 ft | 8.72 | 0.1743 |
| 100 ft | 17.43 | 0.1743 |
| 250 ft | 43.58 | 0.1743 |
| 500 ft | 87.16 | 0.1743 |
Schedule 40 pipe: volume across sizes
Volume held by a fixed 100 ft run across common Schedule 40 sizes, in US gal. Doubling the diameter roughly quadruples the capacity.
| Nominal size | Bore (in) | Volume in 100 ft (US gal) |
|---|---|---|
| 1/2" | 0.622 | 1.58 |
| 3/4" | 0.824 | 2.77 |
| 1" | 1.049 | 4.49 |
| 1-1/2" | 1.610 | 10.58 |
| 2" | 2.067 | 17.43 |
| 3" | 3.068 | 38.40 |
| 4" | 4.026 | 66.13 |
| 6" | 6.065 | 150.1 |
Worked example, step by step
- Bore = 2.067 in, so radius = 1.0335 in.
- Area = π × radius² = 3.3556 in².
- Length = 75 ft = 900 in; volume = 3.3556 × 900 = 3,020.0 in³.
- Convert to the unit you need: 13.07 US gal for a 75 ft run of Schedule 40 2" pipe.
Frequently asked questions
How do I calculate the volume of water in a PVC pipe?
Choose the PVC schedule and size above to load the bore, enter the length, and read the volume in gallons or litres. Behind the scenes it applies V = π × (ID/2)² × L with the true Schedule 40 or 80 inside diameter.
Is Schedule 40 and Schedule 80 PVC volume different?
Yes. Schedule 80 has a thicker wall and a smaller bore, so it holds slightly less per foot than Schedule 40 of the same nominal size. Pick the correct schedule for an accurate result.
What is the inside diameter of 2-inch PVC?
Schedule 40 2-inch PVC has a 2.067 in bore; Schedule 80 is 1.939 in. The outside diameter is 2.375 in for both.
Can I use this for CPVC or DWV pipe?
Pressure CPVC follows the same schedule bores, so Schedule 40/80 works. DWV and foam-core pipe can differ, so measure the bore and use Custom mode for those.
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What people say
Used the litres-per-metre figures to size a glycol charge for a radiant job. Numbers matched the datasheet.
Switches between US and metric without losing the pipe. Small thing, big time-saver.
Would love more HDPE DIPS sizes, otherwise excellent.