Sizes chart
| Nominal size | DN | Outside Ø (mm) | Sch 40 wall (mm) | Sch 80 wall (mm) |
|---|---|---|---|---|
| ½" | 15 | 21.3 | 2.77 | 3.73 |
| ¾" | 20 | 26.7 | 2.87 | 3.91 |
| 1" | 25 | 33.4 | 3.38 | 4.55 |
| 1¼" | 32 | 42.2 | 3.56 | 4.85 |
| 1½" | 40 | 48.3 | 3.68 | 5.08 |
| 2" | 50 | 60.3 | 3.91 | 5.54 |
| 2½" | 65 | 73.0 | 5.16 | 7.01 |
| 3" | 80 | 88.9 | 5.49 | 7.62 |
| 4" | 100 | 114.3 | 6.02 | 8.56 |
| 5" | 125 | 141.3 | 6.55 | 9.53 |
| 6" | 150 | 168.3 | 7.11 | 10.97 |
| 8" | 200 | 219.1 | 8.18 | 12.70 |
| 10" | 250 | 273.1 | 9.27 | 15.09 |
| 12" | 300 | 323.9 | 10.31 | 17.48 |
What schedule means
Schedule is a series of wall thicknesses, not a pressure rating on its own. The same schedule gives a thicker wall as the pipe gets bigger, so 6 inch schedule 40 has a far heavier wall than 1 inch schedule 40.
Inside diameter is the outside diameter less two walls. A 2 inch schedule 40 pipe has a bore of about 52.5 mm. In schedule 80 it is about 49.2 mm.
Nominal size is not the outside diameter
Up to 12 inch the nominal size is a trade name, not a measurement. A 2 inch pipe measures 60.3 mm across the outside. To identify a pipe you already have, measure the outside diameter with a vernier and the wall at a cut end, then match both to the chart.
Schedule 40 or 80?
Schedule 40 is the standard wall for most water, air and general process lines, and for structural uses such as posts and handrails. Schedule 80 is chosen for higher pressure, for pipe that will be threaded, since the thread is cut into the wall, and where corrosion or erosion will thin the wall over time.
The pressure a pipe may carry depends on the material, the temperature and the design code. Take the rating from your engineer or the code, not from the schedule alone.
Ordering schedule pipe
- Nominal size, or the outside diameter if you are matching existing pipe
- Schedule, for example 40 or 80
- Material: mild steel, or stainless with the grade (see 304 vs 316)
- Full lengths, or the cut lengths you need
- Quantity and delivery town
We stock mild steel and stainless schedule pipe in full lengths or cut to size.