HDPE 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 |
|---|
HDPE bore depends on the DR. Pick your dimension ratio — DR11 is a common pressure default.
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.
How the DR sets the HDPE bore
HDPE pipe holds a constant ratio between outside diameter and wall thickness — the dimension ratio (DR). A lower DR means a thicker wall, a higher pressure rating and a smaller bore; a higher DR means a thinner wall and a larger bore. The bore is derived directly:
ID = OD × (1 − 2 / DR)
The calculator uses the IPS outside diameter for your size and the DR you pick.
For 4-inch IPS HDPE (OD 4.5 in): DR11 gives a 3.68 in bore, while DR17 gives 3.97 in — a volume difference of about 16% for the same nominal pipe. That is why picking the right DR matters.
Where HDPE volume is needed
- Water and gas mains — line fill, disinfection and purge volumes.
- Geothermal loops — loop volume drives the antifreeze charge.
- Mining and industrial slurry lines — content and displacement estimates.
- Fused pipeline sections — total contents for hydrotest and commissioning.
A DR-aware example
Take 1,000 ft of 6-inch IPS DR11 HDPE. The OD is 6.625 in, so the bore is about 5.42 in; each foot holds roughly 1.20 US gallons, and the run totals about 1,199 gallons — close to 28.5 barrels. Switch the DR to 17 and the same run climbs to roughly 1,394 gallons. The calculator recalculates the moment you change the DR.
IPS vs DIPS sizing
This tool uses IPS (iron pipe size) outside diameters, which match steel and PVC OD and cover most municipal and industrial HDPE. DIPS (ductile-iron pipe size) HDPE has larger outside diameters for the same nominal — if your pipe is DIPS, measure the OD and use Custom OD mode with the wall thickness, or enter the measured bore directly, so the volume reflects the real pipe.
Keeping HDPE volume accurate
Always confirm the DR from the pipe print, not the nominal size, and check whether it is IPS or DIPS. For long fused runs, use the fittings allowance to approximate the extra volume in bends and account for any part-filled sections with the fill-level setting.
Reading and trusting your result
Before you act on the output, it helps to know exactly what this hdpe pipe 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.
DR11 2" IPS line: capacity down the run
HDPE holds less than its outside size suggests, because the wall eats into the bore. Here is a 2" IPS DR11 line (bore 1.943 in) as the run lengthens — read straight off, or multiply the per-foot figure.
| Length (ft) | Volume (US gal) | Per foot |
|---|---|---|
| 10 ft | 1.54 | 0.1541 |
| 25 ft | 3.85 | 0.1541 |
| 50 ft | 7.71 | 0.1541 |
| 100 ft | 15.41 | 0.1541 |
| 250 ft | 38.53 | 0.1541 |
| 500 ft | 77.06 | 0.1541 |
DR11 capacity across IPS sizes
Because DR is a ratio, every DR11 size has the same wall-to-diameter proportion — so the bore, and the volume in a fixed 100 ft run, scale with the IPS outside diameter shown.
| IPS size | Bore (in) | Volume in 100 ft (US gal) |
|---|---|---|
| 1" | 1.076 | 4.72 |
| 2" | 1.943 | 15.41 |
| 3" | 2.864 | 33.47 |
| 4" | 3.682 | 55.33 |
| 6" | 5.420 | 119.9 |
| 8" | 7.057 | 203.2 |
A worked figure
- Take a 2" IPS DR11 pipe: OD 2.375 in, wall = OD ÷ 11 = 0.216 in.
- Bore = 2.375 − 2 × 0.216 = 1.943 in, so radius = 0.9715 in.
- Cross-section = π × 0.9715² = 2.965 in²; over 300 ft that is 2.965 × 3,600 in = 10,675 in³.
- That works out to 46.2 US gal for a 300 ft DR11 2" run — switch DR and the bore, and this number, change with it.
Frequently asked questions
How do I calculate HDPE pipe volume?
Pick the IPS size and DR so the tool derives the bore from ID = OD × (1 − 2/DR), then enter the length. The volume appears in gallons, litres, m³ and barrels.
Does DR change the volume of HDPE pipe?
Yes — a lower DR means a thicker wall and smaller bore, so less volume per foot. Always match the DR to your actual pipe.
What bore does 4-inch DR11 HDPE have?
About 3.68 in, from a 4.5 in OD and DR11. DR17 of the same size is about 3.97 in.
Is this IPS or DIPS HDPE?
The built-in sizes are IPS. For DIPS pipe, measure the OD and use Custom OD mode with the wall thickness, or enter the measured bore.
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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.