Pipe Volume Calculator — Litres
Same volume in every unit
Fluid weight
Estimated fill / drain time
Your recent calculations (saved on this device)
| When | ID | Length | Result |
|---|
Metric defaults are pre-set: diameter in mm, length in metres, result in litres.
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.
Built for metric pipework
Enter the inside diameter in millimetres and the length in metres and read litres straight off. The maths is simple once the units line up: convert the bore to metres, take the cross-sectional area in square metres, multiply by length in metres to get cubic metres, then multiply by 1,000 to get litres.
Litres = π × (IDm / 2)² × Lm × 1000
Litres per metre of Schedule 40 pipe
The litres-per-metre value is the metric cousin of gallons-per-foot: multiply it by your run length for a quick estimate. Exact figures for any bore and fill level come from the calculator above.
| Nominal size | Inside diameter | Litres / m | Litres / 10 m |
|---|---|---|---|
| 1/2" | 15.8 mm | 0.196 | 1.96 |
| 3/4" | 20.9 mm | 0.344 | 3.44 |
| 1" | 26.6 mm | 0.558 | 5.58 |
| 1-1/4" | 35.1 mm | 0.965 | 9.65 |
| 1-1/2" | 40.9 mm | 1.313 | 13.13 |
| 2" | 52.5 mm | 2.165 | 21.65 |
| 2-1/2" | 62.7 mm | 3.089 | 30.89 |
| 3" | 77.9 mm | 4.769 | 47.69 |
| 4" | 102.3 mm | 8.213 | 82.13 |
| 5" | 128.2 mm | 12.907 | 129.07 |
| 6" | 154.1 mm | 18.639 | 186.39 |
| 8" | 202.7 mm | 32.275 | 322.75 |
| 10" | 254.5 mm | 50.874 | 508.74 |
| 12" | 303.2 mm | 72.214 | 722.14 |
| 24" | 574.6 mm | 259.356 | 2593.56 |
A worked example in litres
Take 25 m of DN50 (2-inch) Schedule 40 pipe, bore 52.5 mm. Area = π × (0.02625)² = 0.002165 m²; volume = 0.002165 × 25 = 0.0541 m³ = 54.1 litres. The same 25 m of DN25 (1-inch, bore 26.6 mm) holds only about 13.9 litres — a reminder that bore dominates capacity because it is squared.
Common metric uses
- Hydronic heating — system litres set the expansion-vessel size and glycol charge.
- Water tanks and rainwater lines — pipe contents add to stored volume.
- Process and dosing — additive rates are quoted per litre of line content.
- Coolant loops — total litres tell you how much glycol mix to mix and add.
From litres to kilograms
Water is close to 1 kg per litre, so litres and kilograms of water are almost interchangeable for planning — 54 litres of water weighs about 54 kg. For coolant and other fluids the density differs, so the calculator lets you pick the fluid and shows the weight in kg and lb.
Reading and trusting your result
Before you act on the output, it helps to know exactly what this pipe volume calculator litres is and isn't measuring.
Reading the output correctly
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 litres. Multiply or interpolate for your exact length.
| Length (m) | Volume (litres) | Per metre |
|---|---|---|
| 3 m | 6.49 | 2.16 |
| 8 m | 17.32 | 2.16 |
| 15 m | 32.47 | 2.16 |
| 30 m | 64.95 | 2.16 |
| 75 m | 162.4 | 2.16 |
| 150 m | 324.7 | 2.16 |
Schedule 40 pipe: volume across sizes
Volume held by a fixed 30 m run across common Schedule 40 sizes, in litres. Because the bore is squared, capacity climbs fast with size.
| Nominal size | Bore (in) | Volume in 30 m (litres) |
|---|---|---|
| 1/2" | 0.622 | 5.88 |
| 3/4" | 0.824 | 10.32 |
| 1" | 1.049 | 16.73 |
| 1-1/2" | 1.610 | 39.40 |
| 2" | 2.067 | 64.95 |
| 3" | 3.068 | 143.1 |
| 4" | 4.026 | 246.4 |
| 6" | 6.065 | 559.2 |
Worked example, step by step
- Bore = 2.067 in = 0.0525 m, so radius = 0.02625 m.
- Area = π × radius² = 0.002165 m².
- Volume = area × length = 0.002165 × 25 = 0.05412 m³.
- Convert: 0.05412 m³ = 54.12 litres for a 25 m run.
Frequently asked questions
How do I calculate pipe volume in litres?
Convert the bore to metres, compute π × (radius)² for the area in m², multiply by the length in metres, then multiply by 1,000. Or enter mm and metres in the calculator and read litres directly.
How many litres per metre in a pipe?
It depends only on the bore. A 50 mm bore holds about 1.96 litres per metre; a 25 mm bore about 0.49 litres per metre. See the litres-per-metre table above.
How do I convert litres to cubic metres?
Divide litres by 1,000. The result panel shows both, so you never have to convert manually.
Is 1 litre of water 1 kilogram?
Very nearly — water is about 0.998 kg per litre at room temperature. For quick planning, treat litres of water and kilograms as equal.
Related pipe volume tools
What people say
The fill-time estimate turned a vague flush task into a scheduled one. Handy.
Clear about its own limits — tells you when to check manufacturer data. Trustworthy.
Clean and quick on my phone in the field.