A pipe schedule chart tells you the wall thickness of a pipe for each nominal pipe size (NPS). The higher the schedule, the thicker the wall: Schedule 40 is the everyday weight, Schedule 80 is heavier, and XXS (double extra strong) is heavier still, while the outside diameter of a given NPS stays the same in every schedule.
Below are the steel pipe dimensions and weights for Schedule 40 (Standard), Schedule 80 (Extra Strong) and XXS, how to read the chart, and the traps that catch people when they order pipe by name instead of by wall thickness.
How Pipe Sizes Work: NPS, OD and Schedule
Steel pipe is named by two things: a nominal size and a wall thickness.
- NPS (nominal pipe size) is a trade name, not a measurement. From NPS 1/2 to NPS 12 the outside diameter is larger than the number: a 2-inch pipe is 2.375 in. outside, and a 4-inch pipe is 4.5 in. From NPS 14 up, the outside diameter equals the nominal size.
- Schedule (Sch 40, Sch 80) or weight class (STD, XS, XXS) sets the wall thickness.
- The outside diameter is fixed for each NPS. Going from Schedule 40 to Schedule 80 makes the wall thicker by shrinking the inside diameter. That is why fittings, threads and clamps for one NPS fit every schedule of that size.
Schedule 40 (Standard) Steel Pipe Chart
Dimensions and weights below are from the AISC Shapes Database v16.0 (checked October 2026), which lists steel pipe as STD, XS and XXS shapes. For NPS 1/2 through 10, the Standard wall in that database is the same wall published as Schedule 40 in the Wheatland Tube ASTM A53 Type E submittal sheet (checked October 2026), which labels the column “Standard (Sch. 40)”. Weights are for plain-end black pipe.
| NPS | OD (in) | ID (in) | Wall (in) | Weight (lb/ft) |
|---|---|---|---|---|
| 1/2 | 0.840 | 0.622 | 0.109 | 0.85 |
| 3/4 | 1.050 | 0.824 | 0.113 | 1.13 |
| 1 | 1.315 | 1.05 | 0.133 | 1.68 |
| 1-1/4 | 1.660 | 1.38 | 0.140 | 2.27 |
| 1-1/2 | 1.900 | 1.61 | 0.145 | 2.72 |
| 2 | 2.375 | 2.07 | 0.154 | 3.66 |
| 2-1/2 | 2.875 | 2.47 | 0.203 | 5.80 |
| 3 | 3.500 | 3.07 | 0.216 | 7.58 |
| 3-1/2 | 4.000 | 3.55 | 0.226 | 9.12 |
| 4 | 4.500 | 4.03 | 0.237 | 10.8 |
| 5 | 5.563 | 5.05 | 0.258 | 14.6 |
| 6 | 6.625 | 6.07 | 0.280 | 19.0 |
| 8 | 8.625 | 7.98 | 0.322 | 28.6 |
| 10 | 10.750 | 10.0 | 0.365 | 40.5 |
Schedule 80 (Extra Strong) Steel Pipe Chart
For NPS 1/2 through 8, the Extra Strong (XS) wall matches the Schedule 80 wall listed by Wheatland. Same outside diameters as Schedule 40, thicker walls, smaller bores.
| NPS | OD (in) | ID (in) | Wall (in) | Weight (lb/ft) |
|---|---|---|---|---|
| 1/2 | 0.840 | 0.546 | 0.147 | 1.09 |
| 3/4 | 1.050 | 0.742 | 0.154 | 1.48 |
| 1 | 1.315 | 0.957 | 0.179 | 2.17 |
| 1-1/4 | 1.660 | 1.28 | 0.191 | 3.00 |
| 1-1/2 | 1.900 | 1.50 | 0.200 | 3.63 |
| 2 | 2.375 | 1.94 | 0.218 | 5.03 |
| 2-1/2 | 2.875 | 2.32 | 0.276 | 7.67 |
| 3 | 3.500 | 2.90 | 0.300 | 10.3 |
| 3-1/2 | 4.000 | 3.36 | 0.318 | 12.5 |
| 4 | 4.500 | 3.83 | 0.337 | 15.0 |
| 5 | 5.563 | 4.81 | 0.375 | 20.8 |
| 6 | 6.625 | 5.76 | 0.432 | 28.6 |
| 8 | 8.625 | 7.63 | 0.500 | 43.4 |
XXS (Double Extra Strong) Pipe Chart
XXS is a weight class, not a schedule number. It is made in a narrower range of sizes and is used where a very thick wall is wanted, such as short heavy struts, high-pressure work or parts that will be machined.
| NPS | OD (in) | ID (in) | Wall (in) | Weight (lb/ft) |
|---|---|---|---|---|
| 2 | 2.375 | 1.50 | 0.436 | 9.04 |
| 2-1/2 | 2.875 | 1.77 | 0.552 | 13.7 |
| 3 | 3.500 | 2.30 | 0.600 | 18.6 |
| 4 | 4.500 | 3.15 | 0.674 | 27.6 |
| 5 | 5.563 | 4.06 | 0.750 | 38.6 |
| 6 | 6.625 | 4.90 | 0.864 | 53.2 |
| 8 | 8.625 | 6.88 | 0.875 | 72.5 |
| 10 | 10.750 | 8.94 | 1.000 | 104 |
| 12 | 12.750 | 10.9 | 1.000 | 126 |
Large Pipe: STD and XS Above NPS 10
For bigger pipe, the AISC database gives every size from NPS 12 to NPS 26 the same Standard wall of 0.375 in and the same Extra Strong wall of 0.500 in. These rows are listed by weight class only. Schedule numbers and weight classes stop lining up in the large sizes, so this chart does not attach a schedule number to them.
| NPS | OD (in) | STD weight (lb/ft), 0.375 in wall | XS weight (lb/ft), 0.500 in wall |
|---|---|---|---|
| 10 | 10.750 | 40.5 (0.365 in wall) | 54.8 |
| 12 | 12.750 | 49.6 | 65.5 |
| 14 | 14.000 | 54.6 | 72.2 |
| 16 | 16.000 | 62.6 | 82.9 |
| 18 | 18.000 | 70.7 | 93.5 |
| 20 | 20.000 | 78.7 | 104 |
| 24 | 24.000 | 94.7 | 126 |
| 26 | 26.000 | 103 | 136 |
Schedule 40 vs Schedule 80: What Changes
Schedule 80 is not a bigger pipe. It is the same pipe with a thicker wall. Moving from Schedule 40 to Schedule 80 at the same NPS:
- Weight goes up by about 30 to 50 percent for most sizes. NPS 2 goes from 3.66 to 5.03 lb/ft, NPS 4 from 10.8 to 15.0 lb/ft and NPS 8 from 28.6 to 43.4 lb/ft.
- The bore gets smaller. That reduces flow area. An NPS 1 pipe drops from a 1.05 in to a 0.957 in inside diameter.
- Threading leaves more metal. Pipe threads are cut into the outside of the wall, so a thicker wall keeps more material under the thread.
- The outside diameter, fittings and threads stay the same. A Schedule 80 nipple screws into the same fitting as a Schedule 40 one.
Which one a job needs is set by the pressure rating, the code that governs the system and the designer. For structural uses such as pipe columns, handrails and bollards, a licensed structural engineer has to size the pipe and check it for the actual loads; a heavier schedule is not automatically safe, and a lighter one is not automatically unsafe.
How to Read a Pipe Schedule Chart Without Mistakes
Measure the outside, not the inside
To identify an unknown pipe, measure the outside diameter with calipers and match it to the OD column. Then measure the wall at a cut end to find the schedule. A pipe with a 2.375 in OD is NPS 2 whether the wall is 0.154 in or 0.436 in.
Pipe is not tube
Round structural tubing (HSS) is named by its actual outside diameter and wall, for example HSS4.500×0.237, while pipe is named by NPS and schedule. Some HSS rounds share pipe outside diameters, but the specifications, tolerances and design walls differ. Our round steel tube sizes chart and the wider HSS sizes guide cover tube; this page covers pipe.
Use the design wall for structural checks
The AISC database lists two walls for each pipe: the nominal wall shown in the charts above and a smaller design wall. For NPS 4 Standard, those are 0.237 in and 0.221 in, so the design wall is about 93 percent of nominal. Section properties used in structural design are based on the design wall, which is one more reason pipe sizing belongs with the engineer of record.
Order by wall thickness on large sizes
Above NPS 10 for Standard and NPS 8 for Extra Strong, write the wall thickness in inches on the order (for example “NPS 12 x 0.375 in wall”). It removes any doubt about which table the supplier is reading from.
Calculating Pipe Weight Yourself
Pipe weight is the area of the steel ring times the density of steel, 490 lb/ft³. In US units that works out to:
Weight (lb/ft) = 10.69 × (OD − wall) × wall, with OD and wall in inches.
Check it on NPS 4 Schedule 40: 10.69 × (4.500 − 0.237) × 0.237 = 10.80 lb/ft, which matches the chart. The same formula drives our steel tubing weight calculator, so you can enter any OD and wall there. Galvanized pipe weighs a little more than black pipe because of the zinc coating.
Where Steel Pipe Shows Up in Buildings
Outside plumbing and gas work, steel pipe is common in light structural roles: basement posts and lally columns, canopy supports, guardrails, bollards and fence posts. Standard and Extra Strong pipe are also listed as structural shapes in the AISC Manual, next to wide flanges and HSS. As with any steel column, the capacity depends on length, end conditions, grade and loads, and has to be worked out by a licensed structural engineer for the specific job.
Pipe Schedule Chart FAQ
Is Schedule 40 the same as Standard weight?
For steel pipe from NPS 1/2 through NPS 10, yes: the walls are the same. Above NPS 10 they can differ, so specify the wall thickness in inches on large pipe.
Is Schedule 80 thicker than Schedule 40?
Yes. At the same NPS, Schedule 80 has a thicker wall and a smaller inside diameter. The outside diameter is identical, so the two use the same fittings and threads.
What is the outside diameter of 2-inch pipe?
2.375 in, in every schedule. Schedule 40 has a 2.07 in bore and Schedule 80 a 1.94 in bore.
How much does Schedule 40 steel pipe weigh per foot?
It depends on size: 1.68 lb/ft for NPS 1, 3.66 lb/ft for NPS 2, 10.8 lb/ft for NPS 4 and 19.0 lb/ft for NPS 6, plain-end black pipe.
Does a pipe schedule chart apply to PVC?
PVC uses the same schedule names and outside diameters for many sizes, but its walls, weights and pressure ratings come from plastic pipe standards. Use a PVC manufacturer’s chart for plastic pipe; the weights on this page are for steel.
Reference information only, not engineering advice. Disclaimer.