PEX Tubing Size Chart
Quick answer: North American plumbing PEX is commonly sized as CTS tubing. The nominal label is not its measured inside diameter: 1/2-inch PEX has a 0.625-inch average outside diameter and about a 0.475-inch calculated inside diameter in the PPI reference.
Standard CTS PEX Dimensions
This chart follows the Plastic Pipe Institute’s ASTM F876 dimension summary for SDR 9 PEX. OD means outside diameter, ID means inside diameter, and the wall column is the average wall thickness shown in that reference. Actual product tolerances and markings are manufacturer-specific.
| Nominal CTS size | Average OD | Average wall | Calculated ID |
|---|---|---|---|
| 3/8 in | 0.500 in / 12.70 mm | 0.075 in / 1.91 mm | 0.350 in / 8.9 mm |
| 1/2 in | 0.625 in / 15.88 mm | 0.075 in / 1.91 mm | 0.475 in / 12.1 mm |
| 5/8 in | 0.750 in / 19.05 mm | 0.088 in / 2.24 mm | 0.574 in / 14.6 mm |
| 3/4 in | 0.875 in / 22.23 mm | 0.102 in / 2.59 mm | 0.671 in / 17.0 mm |
| 1 in | 1.125 in / 28.58 mm | 0.132 in / 3.35 mm | 0.862 in / 21.9 mm |
| 1-1/4 in | 1.375 in / 34.93 mm | 0.161 in / 4.09 mm | 1.054 in / 26.8 mm |
| 1-1/2 in | 1.625 in / 41.28 mm | 0.191 in / 4.85 mm | 1.244 in / 31.6 mm |
| 2 in | 2.125 in / 53.98 mm | 0.248 in / 6.30 mm | 1.629 in / 41.4 mm |
8 rows
Scroll horizontally to view all columns.
How to Use the Dimensions
- CTS describes the outside-diameter series; nominal size is not the tube’s actual ID.
- These are standard SDR 9 PEX dimensions. Do not apply the chart to PEX-AL-PEX, IPS/iron-pipe-size products, or another dimension series without checking its specification.
- Copper-tube-size outside diameters can make some fittings share dimensions, but this does not make every copper, CPVC, and PEX fitting interchangeable. Use fittings specifically listed for the tubing material, size, and joining method.
- Expansion, crimp, clamp, and push-fit systems have their own approved fitting and installation requirements. Follow the tubing and fitting manufacturers’ instructions and local code.
- For water-flow design, use the product’s actual ID, fitting losses, developed length, pressure, temperature, and applicable plumbing requirements. This dimensional chart is not a flow-capacity or fixture-sizing chart.
See the Plastic Pipe Institute PEX dimensions and standards reference and the Viega PureFlow product data sheet for product-specific dimensions and installation details.
Related references: pipe size chart in mm and inches and PVC pipe sizes chart.
