Pipeline Volume Calculator
Same volume in every unit
Fluid weight
Estimated fill / drain time
Your recent calculations (saved on this device)
| When | ID | Length | Result |
|---|
For long lines, enter the length in feet or metres. Result defaults to barrels; switch as needed.
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.
Line fill is capacity times length
A pipeline's line fill — the volume it holds when full — is the per-length capacity multiplied by the run length. Nothing about the formula changes with scale; only the length does. Because gathering and transmission lines run for thousands of feet or many miles, the per-foot capacity is the workhorse figure, and the calculator reports it alongside the total so you can sanity-check a long run.
A transmission-scale example
Consider 5 miles (26,400 ft) of 12-inch line with an 11.938 in bore. Capacity is about 5.815 US gallons per foot, so the line fill is roughly 153,500 US gallons — close to 3,655 barrels or 581 m³. That single figure feeds hydrotest water volume, batch interface tracking and the product lost or recovered when a section is opened.
What pipeline volume drives
- Hydrotest fill — water needed to charge a section for pressure testing.
- Batching and interfaces — line fill sets the timing of product changes.
- Pigging and flushing — sweep and flush volumes.
- Isolation and blowdown — inventory in an isolated section.
Adding up sections
Real pipelines change diameter along their length. Calculate each constant-diameter section separately and add the results — the device keeps your recent calculations so you can tally sections without losing track. Where a line runs part full or is being packed, the fill-level and pressure context change what "volume" means, so use the geometric figure as the reference capacity and adjust for operating conditions.
Accuracy at scale
Small bore errors are magnified over long runs, so use the true internal diameter for the exact grade, wall and any liner. Scale, wax or deposits reduce effective bore over a line's life. For gas pipelines, remember the geometric volume is the physical space; the standard-condition gas quantity also depends on pressure and temperature.
Reading and trusting your result
Before you act on the output, it helps to know exactly what this pipeline volume calculator 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 barrels. The per-foot figure is constant, so any length is one multiplication away.
| Length (ft) | Volume (barrels) | Per foot |
|---|---|---|
| 10 ft | 0.0415 | 0.0042 |
| 25 ft | 0.1038 | 0.0042 |
| 50 ft | 0.2075 | 0.0042 |
| 100 ft | 0.4150 | 0.0042 |
| 250 ft | 1.04 | 0.0042 |
| 500 ft | 2.08 | 0.0042 |
Schedule 40 pipe: volume across sizes
Volume held by a fixed 100 ft run across common Schedule 40 sizes, in barrels. Doubling the diameter roughly quadruples the capacity.
| Nominal size | Bore (in) | Volume in 100 ft (barrels) |
|---|---|---|
| 1/2" | 0.622 | 0.0376 |
| 3/4" | 0.824 | 0.0660 |
| 1" | 1.049 | 0.1069 |
| 1-1/2" | 1.610 | 0.2518 |
| 2" | 2.067 | 0.4150 |
| 3" | 3.068 | 0.9144 |
| 4" | 4.026 | 1.57 |
| 6" | 6.065 | 3.57 |
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: 0.3113 barrels for a 75 ft run of Schedule 40 2" pipe.
Frequently asked questions
How do I calculate pipeline volume?
Multiply the per-foot (or per-metre) capacity by the run length. Enter the bore and length above and the tool gives line fill in barrels, m³ and gallons.
How do I handle a pipeline with different diameters?
Calculate each constant-diameter section separately and add them. The saved history helps you tally sections.
What is line fill?
Line fill is the volume a pipeline holds when full — its internal capacity. It sets hydrotest water, batch timing and isolated-section inventory.
Does this account for pressure in a gas line?
No — it gives the geometric internal volume. Gas quantity at standard conditions also depends on pressure and temperature and needs a separate correction.
Related pipe volume tools
What people say
Line-fill in barrels for a transfer main — matched our metered volume within a whisker.
Handles long runs and multiple segments cleanly. This is now my go-to for batch planning.
Solid for single-diameter lines; staged-diameter pipelines would be a great addition.