Copper pipe size chart (Type K, L, M).
Copper tube size is nominal. The outside diameter is always 1/8 in larger than the nominal size, so 1/2 in copper has a 0.625 in OD. Type K has the thickest wall, Type L is medium and Type M is the thinnest. All three have the same OD, so they use the same fittings.
Outside diameter, wall thickness and inside diameter for Type K, L and M copper water tube, 1/4 in to 12 in, with color codes, weight and water volume.
Copper tube sizes: Type K, L and M
Dimensions are in inches, from ASTM B88. Millimetres are in brackets, converted at exactly 25.4 mm per inch and rounded to 0.01 mm. The outside diameter (OD) is the same for Types K, L and M. Only the wall changes, so the inside diameter (ID) changes too.
| Nominal size | OD, in (mm) | K wall, in (mm) | K ID, in (mm) | L wall, in (mm) | L ID, in (mm) | M wall, in (mm) | M ID, in (mm) |
|---|---|---|---|---|---|---|---|
| 1/4 in | 0.375 (9.5) | 0.035 (0.89) | 0.305 (7.75) | 0.030 (0.76) | 0.315 (8.00) | — | — |
| 3/8 in | 0.500 (12.7) | 0.049 (1.24) | 0.402 (10.21) | 0.035 (0.89) | 0.430 (10.92) | 0.025 (0.64) | 0.450 (11.43) |
| 1/2 in | 0.625 (15.9) | 0.049 (1.24) | 0.527 (13.39) | 0.040 (1.02) | 0.545 (13.84) | 0.028 (0.71) | 0.569 (14.45) |
| 5/8 in | 0.750 (19.0) | 0.049 (1.24) | 0.652 (16.56) | 0.042 (1.07) | 0.666 (16.92) | — | — |
| 3/4 in | 0.875 (22.2) | 0.065 (1.65) | 0.745 (18.92) | 0.045 (1.14) | 0.785 (19.94) | 0.032 (0.81) | 0.811 (20.60) |
| 1 in | 1.125 (28.6) | 0.065 (1.65) | 0.995 (25.27) | 0.050 (1.27) | 1.025 (26.03) | 0.035 (0.89) | 1.055 (26.80) |
| 1-1/4 in | 1.375 (34.9) | 0.065 (1.65) | 1.245 (31.62) | 0.055 (1.40) | 1.265 (32.13) | 0.042 (1.07) | 1.291 (32.79) |
| 1-1/2 in | 1.625 (41.3) | 0.072 (1.83) | 1.481 (37.62) | 0.060 (1.52) | 1.505 (38.23) | 0.049 (1.24) | 1.527 (38.79) |
| 2 in | 2.125 (54.0) | 0.083 (2.11) | 1.959 (49.76) | 0.070 (1.78) | 1.985 (50.42) | 0.058 (1.47) | 2.009 (51.03) |
| 2-1/2 in | 2.625 (66.7) | 0.095 (2.41) | 2.435 (61.85) | 0.080 (2.03) | 2.465 (62.61) | 0.065 (1.65) | 2.495 (63.37) |
| 3 in | 3.125 (79.4) | 0.109 (2.77) | 2.907 (73.84) | 0.090 (2.29) | 2.945 (74.80) | 0.072 (1.83) | 2.981 (75.72) |
| 3-1/2 in | 3.625 (92.1) | 0.120 (3.05) | 3.385 (85.98) | 0.100 (2.54) | 3.425 (86.99) | 0.083 (2.11) | 3.459 (87.86) |
| 4 in | 4.125 (104.8) | 0.134 (3.40) | 3.857 (97.97) | 0.110 (2.79) | 3.905 (99.19) | 0.095 (2.41) | 3.935 (99.95) |
| 5 in | 5.125 (130.2) | 0.160 (4.06) | 4.805 (122.05) | 0.125 (3.17) | 4.875 (123.82) | 0.109 (2.77) | 4.907 (124.64) |
| 6 in | 6.125 (155.6) | 0.192 (4.88) | 5.741 (145.82) | 0.140 (3.56) | 5.845 (148.46) | 0.122 (3.10) | 5.881 (149.38) |
| 8 in | 8.125 (206.4) | 0.271 (6.88) | 7.583 (192.61) | 0.200 (5.08) | 7.725 (196.21) | 0.170 (4.32) | 7.785 (197.74) |
| 10 in | 10.125 (257.2) | 0.338 (8.59) | 9.449 (240.00) | 0.250 (6.35) | 9.625 (244.47) | 0.212 (5.38) | 9.701 (246.41) |
| 12 in | 12.125 (308.0) | 0.405 (10.29) | 11.315 (287.40) | 0.280 (7.11) | 11.565 (293.75) | 0.254 (6.45) | 11.617 (295.07) |
Type K, L, M and DWV compared
Each type has a printed color stripe on the tube. Use the color to identify the type on site.
| Type | Color code | Wall | Standard | Uses listed by the CDA |
|---|---|---|---|---|
| K | Green | Thickest | ASTM B88 | Water service and distribution, fire protection, solar, fuel oil, HVAC, snow melting, compressed air, natural gas, LP gas, vacuum |
| L | Blue | Medium | ASTM B88 | Water service and distribution, fire protection, solar, fuel oil, natural gas, LP gas, HVAC, snow melting, compressed air, vacuum |
| M | Red | Thinnest | ASTM B88 | Water service and distribution, fire protection, solar, fuel oil, HVAC, snow melting, vacuum |
| DWV | Yellow | Thin | ASTM B306 | Drain, waste and vent; HVAC; solar (not a pressure tube) |
The plumbing code for your area decides which types you can use. Check it before you buy tube.
Weight and water volume per length
Weight is for the empty tube, from the CDA tables. Water volume is calculated from the ID: gallons per 100 ft = π ÷ 4 × ID² × 1,200 ÷ 231.
| Size | K lb/ft | L lb/ft | M lb/ft | K gal/100 ft | L gal/100 ft | M gal/100 ft |
|---|---|---|---|---|---|---|
| 1/4 in | 0.145 | 0.126 | — | 0.38 | 0.40 | — |
| 3/8 in | 0.269 | 0.198 | 0.145 | 0.66 | 0.75 | 0.83 |
| 1/2 in | 0.344 | 0.285 | 0.204 | 1.13 | 1.21 | 1.32 |
| 5/8 in | 0.418 | 0.362 | — | 1.73 | 1.81 | — |
| 3/4 in | 0.641 | 0.455 | 0.328 | 2.26 | 2.51 | 2.68 |
| 1 in | 0.839 | 0.655 | 0.465 | 4.04 | 4.29 | 4.54 |
| 1-1/4 in | 1.04 | 0.884 | 0.682 | 6.32 | 6.53 | 6.80 |
| 1-1/2 in | 1.36 | 1.14 | 0.94 | 8.95 | 9.24 | 9.51 |
| 2 in | 2.06 | 1.75 | 1.46 | 15.66 | 16.08 | 16.47 |
| 2-1/2 in | 2.93 | 2.48 | 2.03 | 24.19 | 24.79 | 25.40 |
| 3 in | 4 | 3.33 | 2.68 | 34.48 | 35.39 | 36.26 |
| 3-1/2 in | 5.12 | 4.29 | 3.58 | 46.75 | 47.86 | 48.82 |
| 4 in | 6.51 | 5.38 | 4.66 | 60.70 | 62.22 | 63.18 |
| 5 in | 9.67 | 7.61 | 6.66 | 94.20 | 96.96 | 98.24 |
| 6 in | 13.9 | 10.2 | 8.92 | 134.47 | 139.39 | 141.11 |
| 8 in | 25.9 | 19.3 | 16.5 | 234.61 | 243.48 | 247.27 |
| 10 in | 40.3 | 30.1 | 25.6 | 364.28 | 377.97 | 383.97 |
| 12 in | 57.8 | 40.4 | 36.7 | 522.36 | 545.70 | 550.61 |
How to read copper tube sizes
- Find the nominal size on the tube or the fitting, for example 1/2 in.
- Add 1/8 in to get the outside diameter: 1/2 + 1/8 = 5/8 in (0.625 in).
- Read the color stripe to find the type: green K, blue L, red M.
- Use the row and type in the chart to find the wall and the inside diameter.
Copper tube sizes are not the same as steel pipe sizes. A 1/2 in steel pipe (NPS) has a 0.840 in OD. A 1/2 in copper tube has a 0.625 in OD. See the steel pipe size chart for NPS sizes.
Common questions
What is the outside diameter of 1/2 inch copper pipe?
It is 0.625 in (5/8 in, 15.9 mm) for Types K, L and M. The OD of copper tube is always 1/8 in larger than the nominal size.
What is the difference between Type K, L and M copper?
Only the wall thickness. For 1/2 in tube, Type K has a 0.049 in wall, Type L 0.040 in and Type M 0.028 in. The OD is the same, so all three types use the same fittings.
What color is Type L copper pipe?
Type L has a blue stripe. Type K is green, Type M is red and DWV tube is yellow.
Is copper pipe measured by its inside or outside diameter?
By neither. The size is nominal. For Types K, L and M the outside diameter is the nominal size plus 1/8 in. The inside diameter depends on the type.
How much water does 3/4 inch Type L copper hold?
About 2.51 US gallons per 100 ft. The ID of 3/4 in Type L is 0.785 in.
Which copper type is used for water lines?
The Copper Development Association lists water service and distribution for Types K, L and M. Your local plumbing code decides which type is allowed where, for example underground or inside a building.
Sources
- Dimensions and weights: Copper Development Association, The Copper Tube Handbook, Tables 14.2a (Type K), 14.2b (Type L) and 14.2c (Type M).
- Types, color codes and uses: Copper Tube Handbook, Table 14.1.
- Standards: ASTM B88 — Seamless Copper Water Tube; ASTM B306 — Copper Drainage Tube (DWV).