Pipe Weight Calculator
Mass, internal diameter, water capacity and coating surface area for any NPS size and schedule. The last two are the figures a printed pipe chart leaves out and a piping take-off cannot be finished without.
Water capacity sizes the hydrostatic test pump and the temporary supply; external surface area is the quantity you send to a coating applicator. Both come from the same internal diameter and outside diameter as the weight, so they cannot drift out of step with it.
Schedule 40 pipe — full reference table
Schedule 40 is the most widely specified wall. This is the complete tabulated range, so the page stands on its own without running the calculator.
| Nominal size | Metric size | Outside dia. mm | Wall mm | Inside dia. mm | Mass / length | Imperial | Water capacity L/m |
|---|---|---|---|---|---|---|---|
| NPS 1/8 | DN 6 | 10.3 | 1.73 | 6.8 | 0.365 kg/m | 0.245 lb/ft | 0.037 |
| NPS 1/4 | DN 8 | 13.7 | 2.24 | 9.2 | 0.633 kg/m | 0.425 lb/ft | 0.067 |
| NPS 3/8 | DN 10 | 17.1 | 2.31 | 12.5 | 0.846 kg/m | 0.568 lb/ft | 0.123 |
| NPS 1/2 | DN 15 | 21.3 | 2.77 | 15.8 | 1.268 kg/m | 0.852 lb/ft | 0.196 |
| NPS 3/4 | DN 20 | 26.7 | 2.87 | 20.9 | 1.685 kg/m | 1.132 lb/ft | 0.344 |
| NPS 1 | DN 25 | 33.4 | 3.38 | 26.6 | 2.501 kg/m | 1.681 lb/ft | 0.558 |
| NPS 1-1/4 | DN 32 | 42.2 | 3.56 | 35.1 | 3.386 kg/m | 2.275 lb/ft | 0.965 |
| NPS 1-1/2 | DN 40 | 48.3 | 3.68 | 40.9 | 4.049 kg/m | 2.721 lb/ft | 1.313 |
| NPS 2 | DN 50 | 60.3 | 3.91 | 52.5 | 5.442 kg/m | 3.657 lb/ft | 2.165 |
| NPS 2-1/2 | DN 65 | 73.0 | 5.16 | 62.7 | 8.630 kg/m | 5.799 lb/ft | 3.089 |
| NPS 3 | DN 80 | 88.9 | 5.49 | 77.9 | 11.286 kg/m | 7.584 lb/ft | 4.769 |
| NPS 3-1/2 | DN 90 | 101.6 | 5.74 | 90.1 | 13.571 kg/m | 9.119 lb/ft | 6.379 |
| NPS 4 | DN 100 | 114.3 | 6.02 | 102.3 | 16.075 kg/m | 10.802 lb/ft | 8.213 |
| NPS 4-1/2 | DN 115 | 127.0 | 6.27 | 114.5 | 18.679 kg/m | 12.552 lb/ft | 10.288 |
| NPS 5 | DN 125 | 141.3 | 6.55 | 128.2 | 21.777 kg/m | 14.633 lb/ft | 12.907 |
| NPS 6 | DN 150 | 168.3 | 7.11 | 154.1 | 28.267 kg/m | 18.994 lb/ft | 18.639 |
| NPS 8 | DN 200 | 219.1 | 8.18 | 202.7 | 42.538 kg/m | 28.584 lb/ft | 32.275 |
| NPS 10 | DN 250 | 273.1 | 9.27 | 254.5 | 60.310 kg/m | 40.526 lb/ft | 50.874 |
| NPS 12 | DN 300 | 323.8 | 10.31 | 303.2 | 79.739 kg/m | 53.582 lb/ft | 72.214 |
| NPS 14 | DN 350 | 355.6 | 11.10 | 333.4 | 94.303 kg/m | 63.368 lb/ft | 87.302 |
| NPS 16 | DN 400 | 406.4 | 12.70 | 381.0 | 123.307 kg/m | 82.859 lb/ft | 114.009 |
| NPS 18 | DN 450 | 457.2 | 14.27 | 428.7 | 155.927 kg/m | 104.778 lb/ft | 144.310 |
| NPS 20 | DN 500 | 508.0 | 15.06 | 477.9 | 183.105 kg/m | 123.041 lb/ft | 179.358 |
| NPS 24 | DN 600 | 609.6 | 17.45 | 574.7 | 254.825 kg/m | 171.234 lb/ft | 259.402 |
| NPS 32 | DN 800 | 812.8 | 17.48 | 777.8 | 342.757 kg/m | 230.322 lb/ft | 475.205 |
| NPS 34 | DN 850 | 863.6 | 17.48 | 828.6 | 364.650 kg/m | 245.033 lb/ft | 539.302 |
| NPS 36 | DN 900 | 914.4 | 19.05 | 876.3 | 420.637 kg/m | 282.655 lb/ft | 603.109 |
Outside diameters and wall thicknesses derived from ASME B36.10M. Mass and water capacity computed from geometry at the density shown above.
How to read a pipe schedule
Nominal Pipe Size (NPS) is a label, not a dimension. A 2-inch pipe does not measure 2 inches anywhere — its outside diameter is 60.3 mm (2.375 in) and its bore depends on the wall. NPS was fixed so that the outside diameter stays constant while the wall varies, which is what lets one fitting size serve every schedule.
DN is the metric equivalent of the same label. It is also dimensionless: DN 50 does not mean 50 mm of anything. The two are the same designation under different names, which is why no conversion factor is needed — see the DN to NPS table .
Schedule is the wall thickness series. Higher numbers mean thicker walls at the same nominal size, and therefore less bore and more weight. Above NPS 10 a size typically carries a dozen schedules, which is why the weight difference between two “6-inch pipes” can be a factor of four.
XXS is not a schedule number but a named wall, defined independently. On some sizes it is thinner than Sch 160 and on others thicker, and it is a routine source of ordering errors for precisely that reason.
Frequently asked questions
What is the difference between Schedule 40 and STD?
Schedule 40 and Standard (STD) are the same wall thickness up to and including NPS 10. From NPS 12 they part company: STD is held at 0.375 in while Schedule 40 keeps growing with diameter. So a 24-inch STD pipe is lighter than a 24-inch Sch 40 pipe, and the gap widens as the size increases. The calculator resolves both from the same rule so you can see the difference directly.
How do I calculate the weight of water in a pipe?
Take the internal diameter, work out the internal volume per metre, and multiply by the density of water. The calculator does this for you and reports litres per metre as well as kilograms per metre, because a hydrostatic test is usually specified as a volume or a test pressure rather than a mass. Note we use 1,000 kg/m³, the conventional value for water in piping take-off; at 20 °C real water is about 998 kg/m³, so a test mass is around 0.2 % lower.
What is the outside surface area used for?
Coating and painting quantities. A specification that says “apply 300 microns of epoxy to all external pipe surfaces” is priced from square metres, and so is the abrasive blasting that precedes it. The same figure also gives you the surface area for insulation and heat-trace calculations, though those need the insulated diameter, not the pipe diameter.
Why does my supplier’s chart show a slightly different weight?
Published pipe charts calculate weight at a nominal steel density of roughly 7,844 kg/m³, while we use the real specification density of 7,850 kg/m³ for carbon steel. That is a difference of about 0.1 % — visible in the fourth significant figure, irrelevant to what you order, and present on every chart. The advantage of our approach is that the same geometry can be recalculated for stainless, which is 1.9 % heavier.
Can I enter a custom outside diameter and wall?
Yes — choose “Custom” and enter any outside diameter and wall thickness. The formulas use geometry, not a table, so a non-standard size is calculated exactly as well as a standard one. That is what you want for a machined sleeve or a rolled-and-welded special where the nearest standard size does not apply.
Related reference data
Every schedule has its own reference page, and every size has a page listing all of its schedules.
- Pipe overview — schedules, sizes and how weight is computed
- DN to NPS conversion — metric to imperial designations
- Pipe weight formula — worked derivation
- Metal weight calculator — any size, any material
Outside diameters and wall thicknesses are the dimensional values from ASME B36.10M / B36.19M, stored in inches and converted at exactly 25.4 mm per inch. Mass, water capacity and surface area are computed from that geometry — they are not copied from a 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).
- BIPM / NIST definitional constants: international inch = 25.4 mm, foot = 0.3048 m, pound = 0.45359237 kg.
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.