Pipe dimensions and weight
31 nominal sizes, 17 schedules, one fixed outside diameter per size. Dimensions from ASME B36.10M / B36.19M; mass, bore, water capacity and coating area computed here from the same geometry, at the density of the material you choose.
How a pipe is specified — and why it is confusing
Three separate things have to be stated before a pipe is a pipe, and the industry’s naming convention obscures all three:
- Outside diameter, which is fixed by the standard and by the nominal size. It is the one dimension that must not change, because it is what fittings, flanges and threads grip.
- Wall thickness, expressed as a schedule. Because the outside diameter is fixed, a heavier schedule eats into the bore rather than growing outward.
- Material, which is the only thing that changes the mass for a given geometry — and by up to 3.4× across the materials covered here.
STD is not Sch 40 above NPS 10. Standard wall equals Schedule 40 up to and including NPS 10; from NPS 12 it is held at 0.375 in while Sch 40 grows. Likewise XS is not Sch 80 above NPS 8: Extra Strong equals Schedule 80 up to NPS 8, then holds at 0.500 in. Below the split point the pairs are identical, which is exactly why a line list that mixes the two designations across sizes hides the difference until the pipe arrives.
Schedule 40 quick reference
The default wall for most general-purpose pipe in the world. Carbon steel at 7,850 kg/m³, dimensions from ASME B36.10M. Sch 80 is shown alongside it because the pair is the most common either/or decision on a line list.
| Nominal size | Metric size | Outside dia. mm | Sch 40 wall mm | Sch 40 bore mm | Sch 40 mass kg/m | lb/ft | Sch 80 mass kg/m |
|---|---|---|---|---|---|---|---|
| NPS 1/2 | DN 15 | 21.3 | 2.77 | 15.8 | 1.268 | 0.852 | 1.621 |
| NPS 3/4 | DN 20 | 26.7 | 2.87 | 20.9 | 1.685 | 1.132 | 2.195 |
| NPS 1 | DN 25 | 33.4 | 3.38 | 26.6 | 2.501 | 1.681 | 3.235 |
| NPS 1-1/2 | DN 40 | 48.3 | 3.68 | 40.9 | 4.049 | 2.721 | 5.410 |
| NPS 2 | DN 50 | 60.3 | 3.91 | 52.5 | 5.442 | 3.657 | 7.482 |
| NPS 3 | DN 80 | 88.9 | 5.49 | 77.9 | 11.286 | 7.584 | 15.274 |
| NPS 4 | DN 100 | 114.3 | 6.02 | 102.3 | 16.075 | 10.802 | 22.321 |
| NPS 6 | DN 150 | 168.3 | 7.11 | 154.1 | 28.267 | 18.994 | 42.567 |
| NPS 8 | DN 200 | 219.1 | 8.18 | 202.7 | 42.538 | 28.584 | 64.637 |
| NPS 10 | DN 250 | 273.1 | 9.27 | 254.5 | 60.310 | 40.526 | 95.983 |
| NPS 12 | DN 300 | 323.8 | 10.31 | 303.2 | 79.739 | 53.582 | 131.856 |
| NPS 16 | DN 400 | 406.4 | 12.70 | 381.0 | 123.307 | 82.859 | 203.296 |
| NPS 24 | DN 600 | 609.6 | 17.45 | 574.7 | 254.825 | 171.234 | 441.495 |
Bore falls as wall grows at a fixed outside diameter: NPS 6 Sch 80 carries 25 % more steel and 8 % less bore than Sch 40. Mass, bore and the internal volume are all computed, not copied.
Every schedule
Each schedule page carries its complete size table with wall, bore, metal area, mass and water capacity.
Sch 5S
The thinnest stainless schedule. Chosen for low-pressure, high-purity service where wall thickness is set by handling and welding practice rather than by pressure.
Sch 10S
Common stainless process-piping wall for low-pressure utility and clean service; the stainless counterpart of Sch 10.
Sch 10
A thin carbon-steel wall used for low-pressure water, slurry and ventilation lines. Rarely specified above NPS 24.
Sch 20
An intermediate wall sitting between Sch 10 and Sch 40. It appears mainly on larger sizes where Sch 10 is too thin and Sch 40 is over-specified.
Sch 30
A mid-range wall used where Sch 40 would be heavier than the pressure calculation requires but a standard schedule is still preferred over a non-standard wall.
Sch 40S
The stainless equivalent of Schedule 40 for sizes up to NPS 8. Above NPS 10, 40S holds a 0.375 in wall while carbon Sch 40 keeps growing.
Sch 40 / STD
The default carbon-steel wall — Schedule 40 and Standard (STD) are the same thickness below NPS 12. Most general-purpose pipe in the world is Sch 40.
Sch 60
A non-preferred intermediate wall. It exists mainly so that a mid-pressure line can be specified without moving to a heavier XS wall.
Sch 80S
Stainless Schedule 80 — the standard stainless wall for higher pressure. Above NPS 10 it holds 0.500 in while carbon Sch 80 continues to grow.
Sch 80 / XS
Schedule 80 is Extra Strong (XS) below NPS 10. Above that, XS stays at 0.500 in and Sch 80 becomes progressively heavier.
Sch 100
A non-preferred heavy wall used in high-pressure utility and process service where the next standard step would be too coarse.
Sch 120
A heavy wall for higher-pressure process lines and steam service. Weight per metre rises sharply, so supports and hangers must be checked with it.
Sch 140
A very heavy wall used in high-pressure process and power piping; it is where pipe stops competing with fabricated heavy-wall alternatives on cost.
Sch 160
One of the heaviest tabulated walls, for high-pressure small-bore lines. A Sch 160 line weighs several times its Sch 40 equivalent and needs matching supports.
XXS
Double Extra Strong — a wall thickness, not a schedule. It is defined independently of Sch 160 and on some sizes is thinner and on others thicker, which is a common source of ordering errors.
STD (Standard)
Standard wall. Identical to Schedule 40 up to and including NPS 10; from NPS 12 upward it is fixed at 0.375 in and is therefore lighter than Sch 40.
XS (Extra Strong)
Extra Strong wall. Identical to Schedule 80 up to NPS 8; from NPS 10 upward it is fixed at 0.500 in and is therefore lighter than Sch 80.
By nominal size
The other way in. Each size page lists every schedule tabulated on that outside diameter, which is the view that makes the fixed-OD convention obvious — and where the “2-inch pipe is 60.3 mm” surprise lives.
- NPS 1/8
- NPS 1/4
- NPS 3/8
- NPS 1/2
- NPS 3/4
- NPS 1
- NPS 1-1/4
- NPS 1-1/2
- NPS 2
- NPS 2-1/2
- NPS 3
- NPS 3-1/2
- NPS 4
- NPS 4-1/2
- NPS 5
- NPS 6
- NPS 8
- NPS 10
- NPS 12
- NPS 14
- NPS 16
- NPS 18
- NPS 20
- NPS 22
- NPS 24
- NPS 26
- NPS 28
- NPS 30
- NPS 32
- NPS 34
- NPS 36
Full list on the nominal sizes page , including the sizes that exist in only one of the two designation systems — NPS 4-1/2 and NPS 22 are real, uncommon and easy to overlook.
DN and NPS are labels, not measurements
DN (Diamètre Nominal) is the metric designation and NPS (Nominal Pipe Size) the imperial one. They map cleanly at the round numbers — DN 15 is NPS 1/2, DN 50 is NPS 2, DN 200 is NPS 8 — and the conversion is exact, because DN was defined as the metric counterpart rather than measured independently. What neither designation tells you is a dimension: DN 50 pipe is 60.3 mm outside and 52.5 mm inside in Schedule 40.
Download the pipe dataset
Pipe dimensions and weights
Every size against every schedule, with outside diameter, wall, bore, metal area, mass in both unit systems and internal volume.
Generated at build time from the same source modules the pages render, so the file and the tables cannot drift apart.
Frequently asked questions
What does Schedule 40 mean?
A schedule number is a wall-thickness designation, not a size. Schedule 40 at NPS 2 and Schedule 40 at NPS 24 are the same designation applied to different outside diameters, so the actual wall thickness differs — 3.91 mm at NPS 2 against 17.45 mm at NPS 24. The schedule system exists because the outside diameter is fixed by the standard so that fittings are interchangeable, which means wall thickness has to be expressed separately, and it is expressed as a schedule.
Why is a 2-inch pipe not 2 inches in diameter?
Because NPS is a label inherited from a nineteenth-century sizing convention, not a measurement. NPS 2 pipe has an outside diameter of 60.3 mm (2.375 in) and a bore of 52.5 mm in Schedule 40 — neither is 2 inches. Above NPS 12 the nominal size and the outside diameter genuinely diverge (NPS 14 is 14.000 in OD, NPS 16 is 16.000 in), and below NPS 12 they do not, which is why the rule is impossible to remember as a rule and has to be looked up.
Is Schedule 40 the same as STD?
Up to and including NPS 10, yes. From NPS 12 they part company: Standard wall is held at 0.375 in (9.53 mm) while Schedule 40 keeps growing with diameter, reaching 17.45 mm at NPS 24. So from NPS 12 upward, STD is the lighter of the two — and this is the single most common ordering error in pipe procurement. Schedule 80 and Extra Strong follow the same pattern with the split at NPS 10.
How do I convert DN to NPS?
Multiply DN by 0.0394 to get NPS in inches, and accept that the answer is nominal. DN 50 is NPS 2, DN 100 is NPS 4, DN 200 is NPS 8 — the conversion is exact at those points because DN was defined as the metric counterpart of NPS. Where it gets uncomfortable is at the small end, where DN 6, 8, 10, 15 and 20 map onto NPS 1/8, 1/4, 3/8, 1/2 and 3/4, and at NPS 4-1/2 (DN 115) and NPS 22 (DN 550), which exist in one system but rarely in the other. The full table is on the DN to NPS page.
What wall thickness should I use?
That is a pressure calculation, not a table lookup. The wall has to resist the internal design pressure with a corrosion allowance and a manufacturing tolerance, and for anything safety-related it is governed by a piping code (ASME B31.3 for process piping, B31.1 for power, B31.9 for building services). What this site does is tell you what each wall weighs and what bore it leaves — the two things you need after the code has chosen the schedule.
Why do your weights differ slightly from a mill chart?
Density. Published pipe weight tables are usually calculated at a nominal 0.2833–0.2836 lb/in³ (7,844–7,850 kg/m³) and then rounded. We compute from the specification density of the material you select, so a carbon-steel figure can differ from a printed chart in the fourth significant figure and a 304 stainless figure runs about 1.9 % heavier than the same pipe in steel. The build-time test suite asserts that every published chart value we can check stays within 0.3 % — enough to catch a transcription error, not enough to force us to adopt a rounded-away density.
Pipe reference and tools
The schedule and size pages are the detail; these are the cross-cuts.
- Pipe overview — schedules, sizes and how weight is computed
- All pipe schedules — Sch 5S to XXS
- All nominal sizes — NPS 1/8 to NPS 36
- DN to NPS conversion — metric to imperial designations
- Pipe weight formula — worked derivation
- Pipe weight calculator — any OD and wall
- All calculators — metal weight and pipe weight
- Download the data — CSV, generated from the same source
- Cross-reference tables — DN / NPS / material equivalents
- Methodology and sources — where every number comes from
Outside diameters and wall thicknesses are the tabulated ASME B36.10M / B36.19M values, held in inches because that is what the standards govern. Every mass, bore, internal volume and surface area on this site is computed from that geometry — the standards tabulate dimensions, not weights, and no weight here is copied from any published chart.
- ASME B36.10M — Welded and Seamless Wrought Steel Pipe (dimensional tables).
- ASME B36.19M — Stainless Steel Pipe (dimensional tables).
- ASTM material specifications for each grade named in the material entry (A36, A240/A276, B209/B211/B221, B152/B16/B505, B265/B348, A48, B29, D1784, D3350).
Dataset version 2026.09.1 · dimensions last verified against source 2026-09-21. Found an error? Report it — corrections are issued with a version bump.