This Schedule 40 steel pipe dimensions chart provides common pipe sizes, outside diameters, wall thicknesses and calculated inside diameters in inches and millimeters. Use it to check Schedule 40 steel pipe sizes for specification, fabrication and purchasing.
The dimensions below reference applicable carbon and alloy steel pipe dimensions under ASME B36.10M. Confirm the required material standard and product specification before ordering.
Schedule 40 Steel Pipe Dimensions and Sizes
The table covers common Schedule 40 steel pipe dimensions, from NPS 1/8 to NPS 24. It combines outside diameter, wall thickness and approximate inside diameter in one reference, so you can check the dimensions of a specific pipe size without switching between multiple charts.
| NPS (in.) | DN | OD (in.) | OD (mm) | Wall Thickness (in.) | Wall Thickness (mm) | Approx. ID (in.) | Approx. ID (mm) |
|---|---|---|---|---|---|---|---|
| 1/8 | 6 | 0.405 | 10.3 | 0.068 | 1.73 | 0.269 | 6.83 |
| 1/4 | 8 | 0.540 | 13.7 | 0.088 | 2.24 | 0.364 | 9.25 |
| 3/8 | 10 | 0.675 | 17.1 | 0.091 | 2.31 | 0.493 | 12.52 |
| 1/2 | 15 | 0.840 | 21.3 | 0.109 | 2.77 | 0.622 | 15.80 |
| 3/4 | 20 | 1.050 | 26.7 | 0.113 | 2.87 | 0.824 | 20.93 |
| 1 | 25 | 1.315 | 33.4 | 0.133 | 3.38 | 1.049 | 26.64 |
| 1 1/4 | 32 | 1.660 | 42.2 | 0.140 | 3.56 | 1.380 | 35.05 |
| 1 1/2 | 40 | 1.900 | 48.3 | 0.145 | 3.68 | 1.610 | 40.89 |
| 2 | 50 | 2.375 | 60.3 | 0.154 | 3.91 | 2.067 | 52.50 |
| 2 1/2 | 65 | 2.875 | 73.0 | 0.203 | 5.16 | 2.469 | 62.71 |
| 3 | 80 | 3.500 | 88.9 | 0.216 | 5.49 | 3.068 | 77.93 |
| 3 1/2 | 90 | 4.000 | 101.6 | 0.226 | 5.74 | 3.548 | 90.12 |
| 4 | 100 | 4.500 | 114.3 | 0.237 | 6.02 | 4.026 | 102.26 |
| 5 | 125 | 5.563 | 141.3 | 0.258 | 6.55 | 5.047 | 128.19 |
| 6 | 150 | 6.625 | 168.3 | 0.280 | 7.11 | 6.065 | 154.05 |
| 8 | 200 | 8.625 | 219.1 | 0.322 | 8.18 | 7.981 | 202.72 |
| 10 | 250 | 10.750 | 273.0 | 0.365 | 9.27 | 10.020 | 254.51 |
| 12 | 300 | 12.750 | 323.9 | 0.406 | 10.31 | 11.938 | 303.23 |
| 14 | 350 | 14.000 | 355.6 | 0.438 | 11.13 | 13.124 | 333.35 |
| 16 | 400 | 16.000 | 406.4 | 0.500 | 12.70 | 15.000 | 381.00 |
| 18 | 450 | 18.000 | 457.2 | 0.562 | 14.27 | 16.876 | 428.89 |
| 20 | 500 | 20.000 | 508.0 | 0.594 | 15.09 | 18.812 | 477.42 |
| 24 | 600 | 24.000 | 609.6 | 0.688 | 17.48 | 22.624 | 574.25 |
Note: NPS is a nominal pipe size designation, not the measured outside diameter. DN is also a nominal designation. Inside diameters are calculated from the listed nominal OD and wall thickness and are approximate reference values.
How to Read Schedule 40 Steel Pipe Dimensions
When checking Schedule 40 steel pipe sizes, use the following dimensions together:
- NPS: The nominal pipe size used to identify the pipe.
- Outside diameter (OD): The specified external diameter for that NPS.
- Wall thickness: The nominal pipe wall thickness assigned to Schedule 40.
- Inside diameter (ID): The approximate internal diameter after accounting for the wall thickness.
The inside diameter is calculated as:
ID = OD − (2 × Wall Thickness)
For example, NPS 2 Schedule 40 steel pipe has an OD of 2.375 inches and a nominal wall thickness of 0.154 inches. Its calculated ID is approximately 2.067 inches.
The OD is specified by the nominal pipe size and applicable dimensional standard; the schedule determines the nominal wall thickness. Actual measurements can vary within the tolerances permitted by the relevant specification.
Schedule 40 Steel Pipe Specifications
When sourcing Schedule 40 carbon steel pipe, confirm the dimensional requirements along with the material and delivery specifications.
| Specification | Details to Confirm |
|---|---|
| Pipe size | NPS or specified OD |
| Wall thickness | Schedule 40 |
| Material standard and grade | For example, ASTM A53 or ASTM A106, as required |
| Pipe type | Seamless or welded, where specified |
| Length | Required or agreed supply length |
| Quantity | Required quantity and unit |
| Additional requirements | Inspection documents, marking, surface treatment and export packing, where applicable |
Common supply lengths may include 6 m and 12 m, depending on pipe size, product specification and availability. Confirm the required length and quantity when requesting a quotation.
The dimensional standard and material standard serve different purposes. ASME B36.10M provides applicable dimensions for welded and seamless wrought steel pipe, while the relevant ASTM product specification defines material and product requirements. Confirm both against the purchase specification.
For complete Schedule 80 dimensions, refer to our separate Schedule 80 Steel Pipe Dimensions guide. For weight estimates, use the dedicated steel pipe weight calculation resource rather than relying on dimensions alone.
Schedule 40 Steel Pipe Supply
After confirming the required Schedule 40 steel pipe dimensions, buyers should also specify the material grade, pipe standard, manufacturing type, length and order quantity to ensure the supplied pipes meet project requirements.
We supply steel pipes in common sizes and specifications for distributors, contractors and industrial buyers. If you are sourcing pipes for an upcoming order, visit our Carbon Steel Pipes to review available options or contact us with your required sizes, grades and quantities for a supply inquiry.