1/4 inch pipe dimensions: OD and wall thickness by schedule
Deskely Completions team Singapore
A 1/4 inch pipe, NPS 1/4 or DN 8, has an outside diameter of 13.7 mm (0.540 inches) in every schedule. The nominal size is a name, not a measurement: the outside diameter is larger than 1/4 inch. The schedule sets the wall thickness, and with it the inside diameter and the weight.
The table gives every schedule listed for NPS 1/4 in ASME B36.10M and B36.19M, in mm and inches.
- Outside diameter: 13.7 mm (0.540 in), the same for every schedule.
- Schedule 40: 2.24 mm wall, 9.2 mm inside diameter.
- Schedule 80: 3.02 mm wall, 7.7 mm inside diameter.
- Metric equivalent: DN 8.
1/4 inch pipe dimensions by schedule
| Schedule | Wall mm (in) | ID mm (in) | kg/m (lb/ft) |
|---|---|---|---|
| Schedule 10S | 1.65 (0.065) | 10.40 (0.409) | 0.49 (0.33) |
| STD (standard) | 2.24 (0.088) | 9.22 (0.363) | 0.63 (0.43) |
| Schedule 40 | 2.24 (0.088) | 9.22 (0.363) | 0.63 (0.43) |
| XS (extra strong) | 3.02 (0.119) | 7.66 (0.302) | 0.80 (0.53) |
| Schedule 80 | 3.02 (0.119) | 7.66 (0.302) | 0.80 (0.53) |
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.
1/4 inch pipe outside diameter
The outside diameter of NPS 1/4 pipe is 13.7 mm, or 0.540 inches, whatever the schedule, so 1/4 inch fittings and flanges fit every wall thickness. In metric drawings and specifications the same size is called DN 8.
It is larger than 1/4 inch because, below NPS 14, the nominal size is a traditional name that once roughly matched the bore, not the outside.
Nearby sizes
- 1/8 inch pipe dimensions: OD 10.3 mm
- 3/8 inch pipe dimensions: OD 17.1 mm
Every size and schedule in one table: the pipe schedule chart.
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Frequently asked questions
What is the OD of 1/4 inch pipe?
13.7 mm (0.540 inches), the same for every schedule.
What is the wall thickness of 1/4 inch schedule 40 pipe?
2.24 mm (0.088 in), giving an inside diameter of 9.2 mm (0.363 in).
What is the wall thickness of 1/4 inch schedule 80 pipe?
3.02 mm (0.119 in), giving an inside diameter of 7.7 mm (0.302 in).
What is 1/4 inch pipe in DN?
DN 8.
How much does 1/4 inch schedule 40 pipe weigh?
0.63 kg/m (0.43 lb/ft) for plain-end carbon steel.
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