1/8 inch pipe dimensions: OD and wall thickness by schedule
Deskely Completions team Singapore
A 1/8 inch pipe, NPS 1/8 or DN 6, has an outside diameter of 10.3 mm (0.405 inches) in every schedule. The nominal size is a name, not a measurement: the outside diameter is larger than 1/8 inch. The schedule sets the wall thickness, and with it the inside diameter and the weight.
The table gives every schedule listed for NPS 1/8 in ASME B36.10M and B36.19M, in mm and inches.
- Outside diameter: 10.3 mm (0.405 in), the same for every schedule.
- Schedule 40: 1.73 mm wall, 6.8 mm inside diameter.
- Schedule 80: 2.41 mm wall, 5.5 mm inside diameter.
- Metric equivalent: DN 6.
1/8 inch pipe dimensions by schedule
| Schedule | Wall mm (in) | ID mm (in) | kg/m (lb/ft) |
|---|---|---|---|
| Schedule 10S | 1.24 (0.049) | 7.82 (0.308) | 0.28 (0.19) |
| STD (standard) | 1.73 (0.068) | 6.84 (0.269) | 0.37 (0.25) |
| Schedule 40 | 1.73 (0.068) | 6.84 (0.269) | 0.37 (0.25) |
| XS (extra strong) | 2.41 (0.095) | 5.48 (0.216) | 0.47 (0.32) |
| Schedule 80 | 2.41 (0.095) | 5.48 (0.216) | 0.47 (0.32) |
Nominal dimensions. Weights are for plain-end carbon steel; stainless steel is about 2 percent heavier. Mill tolerances apply, and your project pipe specification takes precedence.
1/8 inch pipe outside diameter
The outside diameter of NPS 1/8 pipe is 10.3 mm, or 0.405 inches, whatever the schedule, so 1/8 inch fittings and flanges fit every wall thickness. In metric drawings and specifications the same size is called DN 6.
It is larger than 1/8 inch because, below NPS 14, the nominal size is a traditional name that once roughly matched the bore, not the outside.
Nearby sizes
- 1/4 inch pipe dimensions: OD 13.7 mm
Every size and schedule in one table: the pipe schedule chart.
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Frequently asked questions
What is the OD of 1/8 inch pipe?
10.3 mm (0.405 inches), the same for every schedule.
What is the wall thickness of 1/8 inch schedule 40 pipe?
1.73 mm (0.068 in), giving an inside diameter of 6.8 mm (0.269 in).
What is the wall thickness of 1/8 inch schedule 80 pipe?
2.41 mm (0.095 in), giving an inside diameter of 5.5 mm (0.216 in).
What is 1/8 inch pipe in DN?
DN 6.
How much does 1/8 inch schedule 40 pipe weigh?
0.37 kg/m (0.25 lb/ft) for plain-end carbon steel.
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