Copper Tube Size (CTS) is typically used to specify the size of copper tubing. It is also used to speficy sizing control for CTS polyetheylene tubing as well.
The following chart shows the OD and applicable ID’s for the most common types of Copper.
Copper Tubing Sizes (CTS) for Plumbing[1] | ||||
---|---|---|---|---|
Nominal size |
Outside diameter (OD) [in (mm)] |
Inside diameter (ID) [in (mm)] |
||
Type K | Type L | Type M | ||
3⁄8 | 1⁄2 (12.7) | 0.402 (10.211) | 0.430 (10.922) | 0.450 (11.430) |
1⁄2 | 5⁄8 (15.875) | 0.528 (13.411) | 0.545 (13.843) | 0.569 (14.453) |
5⁄8 | 3⁄4 (19.05) | 0.652 (16.561) | 0.668 (16.967) | 0.690 (17.526) |
3⁄4 | 7⁄8 (22.225) | 0.745 (18.923) | 0.785 (19.939) | 0.811 (20.599) |
1 | 1 1⁄8 (28.575) | 0.995 (25.273) | 1.025 (26.035) | 1.055 (26.797) |
11⁄4 | 1 3⁄8 (34.925) | 1.245 (31.623) | 1.265 (32.131) | 1.291 (32.791) |
11⁄2 | 1 5⁄8 (41.275) | 1.481 (37.617) | 1.505 (38.227) | 1.527 (38.786) |
2 | 2 1⁄8 (53.975) | 1.959 (49.759) | 1.985 (50.419) | 2.009 (51.029) |
21⁄2 | 2 5⁄8 (66.675) | 2.435 (61.849) | 2.465 (62.611) | 2.495 (63.373) |
3 | 3 1⁄8 (79.375) | 2.907 (73.838) | 2.945 (74.803) | 2.981 (75.717) |
References:
https://en.wikipedia.org/wiki/Copper_tubing