NPS 1 Pipe Dimensions
Outside diameter 1.315 in (33.4 mm) — fixed across every schedule. 8 wall thicknesses from ASME B36.10M, with bore, plain-end weight and flow area for each.
- Nominal size
- NPS 1
- Metric designator
- DN 25
- Outside diameter
- 1.315 in (33.4 mm)
- Schedules listed
- 8
- Standard weight wall
- 0.133 in (3.4 mm)
- Extra strong wall
- 0.179 in (4.5 mm)
Every schedule in NPS 1
Dimensions are given in inches, with the millimetre equivalent beneath in grey.
| Schedule | Wall thickness | Inside diameter | Weight, empty | Flow area (in²) | Water (US gal/ft) |
|---|---|---|---|---|---|
| Sch 5 | 0.0651.65 mm | 1.18530.10 mm | 0.871.29 kg/m | 1.10 | 0.057 |
| Sch 10 | 0.1092.77 mm | 1.09727.86 mm | 1.402.09 kg/m | 0.95 | 0.049 |
| Sch 40 | 0.1333.38 mm | 1.04926.64 mm | 1.682.50 kg/m | 0.86 | 0.045 |
| STD | 0.1333.38 mm | 1.04926.64 mm | 1.682.50 kg/m | 0.86 | 0.045 |
| Sch 80 | 0.1794.55 mm | 0.95724.31 mm | 2.173.23 kg/m | 0.72 | 0.037 |
| XS | 0.1794.55 mm | 0.95724.31 mm | 2.173.23 kg/m | 0.72 | 0.037 |
| Sch 160 | 0.2506.35 mm | 0.81520.70 mm | 2.844.23 kg/m | 0.52 | 0.027 |
| XXS | 0.3589.09 mm | 0.59915.21 mm | 3.665.45 kg/m | 0.28 | 0.015 |
Weight is calculated for carbon steel as w = 10.6802 × t × (OD − t) lb/ft and is the plain-end weight, excluding coatings, linings and fittings.
Standard weight equals Schedule 40 in this size. Extra strong equals Schedule 80.
This size, schedule by schedule
A page for each combination, with bore, weight, water capacity and the matching flange and fitting data.
This size in a schedule chart
Common questions
What is the outside diameter of NPS 1 pipe?
NPS 1 pipe has an outside diameter of 1.315 in (33.4 mm). That outside diameter is fixed: it is identical in every schedule, and only the wall thickness — and therefore the bore — changes from one schedule to the next.
How much does NPS 1 schedule 40 pipe weigh?
1.68 lb/ft (2.50 kg/m) as plain-end carbon steel, on a wall thickness of 0.133 in (3.4 mm).
What is the metric equivalent of NPS 1?
DN 25. DN is a dimensionless designator, not a measurement — DN 25 pipe does not measure 25 mm anywhere. Its actual outside diameter is 33.4 mm.