A stainless steel tube is sized by its actual outside diameter (OD) and wall thickness, for example 25.4 × 1.65 mm or 1/2 in. × 0.065 in. There is no single chart for every tube: metric sizes usually follow EN ISO 1127, while inch sizes are ordered by actual OD with tolerances from a product standard such as ASTM A269.
Metric sizes and masses are from EN ISO 1127:1996 Table 3 (austenitic stainless steel). Inch tolerances are from ASTM A269/A269M-25 Table 4. A269 does not list fixed sizes, so the inch ODs below are common ordering sizes and the inch weights are calculated.
Which tube size chart to use
| You are buying | Size system | Chart |
|---|---|---|
| Metric stainless tube, general use | OD × wall in mm, EN ISO 1127 | This page, and the EN ISO 1127 guide |
| Inch tube for instruments and process lines | Actual OD × wall in inches, ASTM A269 tolerances | This page, and the ASTM A269 guide |
| Pipe | NPS and schedule, not actual OD | Pipe schedule chart |
| Sanitary tube | DIN 11850, ASME BPE | DIN 11850, ASME BPE |
| Square or rectangular tube | Outside sides × wall | Square, rectangular |
| Needle tube | Gauge | ISO 9626 |
Metric stainless steel tube size chart
Conventional mass in kg/m from EN ISO 1127 Table 3. A dash means the standard does not list a mass for that size in this column, not that the tube cannot be made. These are selected columns: the standard runs from 1.0 to 14.2 mm wall and up to 1016 mm OD.
| OD, mm | OD, in. | 1.0 mm | 1.6 mm | 2.0 mm | 2.6 mm | 3.2 mm | 4.0 mm | 5.0 mm |
|---|---|---|---|---|---|---|---|---|
| 10.2 | 0.402 | 0.230 | 0.344 | 0.410 | — | — | — | — |
| 12 | 0.472 | 0.275 | 0.416 | 0.500 | — | — | — | — |
| 12.7 | 0.500 | 0.293 | 0.445 | 0.536 | 0.658 | 0.761 | — | — |
| 16 | 0.630 | 0.376 | 0.577 | 0.701 | — | — | — | — |
| 17.2 | 0.677 | 0.406 | 0.625 | 0.761 | — | 1.12 | — | — |
| 19 | 0.748 | 0.451 | 0.697 | 0.851 | — | — | — | — |
| 20 | 0.787 | 0.476 | 0.737 | 0.901 | — | — | — | — |
| 21.3 | 0.839 | 0.509 | 0.789 | 0.966 | 1.22 | 1.45 | 1.74 | — |
| 25 | 0.984 | 0.601 | 0.937 | 1.15 | 1.46 | — | — | — |
| 25.4 | 1.000 | — | 0.953 | 1.17 | 1.48 | — | — | — |
| 26.9 | 1.059 | 0.649 | 1.01 | 1.25 | 1.58 | 1.90 | 2.29 | — |
| 31.8 | 1.252 | — | 1.21 | 1.49 | 1.90 | 2.29 | 2.78 | — |
| 33.7 | 1.327 | 0.818 | 1.29 | 1.58 | 2.02 | 2.45 | — | — |
| 38 | 1.496 | — | 1.46 | 1.81 | 2.30 | 2.79 | — | — |
| 42.4 | 1.669 | — | 1.63 | 2.02 | 2.59 | 3.14 | — | 4.68 |
| 48.3 | 1.902 | — | 1.87 | 2.31 | 2.97 | 3.61 | — | 5.42 |
| 51 | 2.008 | 1.25 | 1.98 | 2.46 | 3.15 | 3.83 | — | — |
| 60.3 | 2.374 | — | 2.35 | 2.92 | 3.76 | 4.58 | 5.63 | — |
| 63.5 | 2.500 | — | 2.48 | 3.08 | 3.96 | 4.83 | — | — |
| 76.1 | 2.996 | — | 2.98 | 3.70 | 4.78 | — | 7.22 | 8.90 |
| 88.9 | 3.500 | — | 3.49 | 4.35 | 5.61 | 6.86 | 8.51 | — |
| 101.6 | 4.000 | — | — | 4.98 | — | — | 9.77 | — |
| 114.3 | 4.500 | — | 4.52 | 5.62 | 7.27 | — | — | — |
| 139.7 | 5.500 | — | 5.53 | 6.89 | 8.92 | 11.0 | 13.6 | 16.8 |
| 168.3 | 6.626 | — | 6.68 | 8.32 | 10.8 | 13.2 | 16.4 | 20.4 |
| 219.1 | 8.626 | — | — | 10.9 | 14.1 | 17.3 | 21.5 | — |
EN ISO 1127 diameter series
The standard lists outside diameters in three columns. It does not define what the series mean, so ask for the series only if your drawing or product standard calls for it.
| EN ISO 1127 column | Outside diameters, mm |
|---|---|
| Series 1 | 10.2, 13.5, 17.2, 21.3, 26.9, 33.7, 42.4, 48.3, 60.3, 76.1, 88.9, 114.3, 139.7, 168.3, 219.1, 273, 323.9, 355.6, 406.4, 457, 508, 610, 711, 813, 914, 1016 |
| Series 2 | 6, 8, 10, 12, 12.7, 16, 19, 20, 25, 31.8, 32, 38, 40, 51, 57, 63.5, 70, 101.6 |
| Series 3 | 14, 18, 22, 25.4, 30, 35, 44.5, 54, 82.5 |
Inch stainless steel tube size chart
Calculated weight in lb/ft at 7.93 g/cm³, with the ASTM A269 outside diameter and wall tolerances for that OD. Other walls can be calculated with the formula below.
| OD, in. | OD, mm | 0.035 in. wall | 0.065 in. wall | 0.083 in. wall | 0.120 in. wall | OD tolerance, ±in. (mm) | Wall tolerance |
|---|---|---|---|---|---|---|---|
| 1/8 | 3.18 | 0.034 | — | — | — | ±0.005 (0.13) | ±15 % |
| 1/4 | 6.35 | 0.081 | 0.130 | — | — | ±0.005 (0.13) | ±15 % |
| 3/8 | 9.53 | 0.129 | 0.218 | 0.262 | — | ±0.005 (0.13) | ±15 % |
| 1/2 | 12.70 | 0.176 | 0.305 | 0.374 | 0.492 | ±0.005 (0.13) | ±10 % |
| 5/8 | 15.88 | 0.223 | 0.393 | 0.486 | 0.655 | ±0.005 (0.13) | ±10 % |
| 3/4 | 19.05 | 0.270 | 0.481 | 0.598 | 0.817 | ±0.005 (0.13) | ±10 % |
| 1 | 25.40 | 0.365 | 0.656 | 0.822 | 1.14 | ±0.005 (0.13) | ±10 % |
| 1 1/4 | 31.75 | 0.459 | 0.832 | 1.05 | 1.46 | ±0.005 (0.13) | ±10 % |
| 1 1/2 | 38.10 | 0.554 | 1.01 | 1.27 | 1.79 | ±0.010 (0.25) | ±10 % |
| 2 | 50.80 | — | 1.36 | 1.72 | 2.44 | ±0.010 (0.25) | ±10 % |
| 2 1/2 | 63.50 | — | 1.71 | 2.17 | 3.08 | ±0.010 (0.25) | ±10 % |
| 3 | 76.20 | — | 2.06 | 2.61 | 3.73 | ±0.010 (0.25) | ±10 % |
| 4 | 101.60 | — | — | 3.51 | 5.03 | ±0.015 (0.38) | ±10 % |
| 5 | 127.00 | — | — | — | 6.32 | ±0.015 (0.38) | ±10 % |
| 6 | 152.40 | — | — | — | 7.62 | ±0.030 (0.76) | ±10 % |
A269 Table 4 sets wider limits in some cases. A wall of 3/4 in. (19.0 mm) or more, or an inside diameter of 60 % or less of the OD, allows ±12.5 %. Tube under 1/2 in. (12.7 mm) ID that cannot be drawn over a mandrel allows ±15 %.
Tube OD vs pipe size
A tube size is its real outside diameter, so a 1/2 in. tube measures 0.500 in. (12.70 mm) across. A pipe size is a nominal name: NPS 1/2 pipe measures 0.840 in. (21.34 mm). Ordering “1/2 inch” without saying tube or pipe can give you the wrong part. See pipe vs tube for the full comparison.
How to calculate tube weight
- EN ISO 1127 masses: kg/m = π × (D − T) × T × 7.85 / 1000 × 1.015, with D and T in mm. For 21.3 × 2.0 mm the result is 0.966 kg/m, the value in Table 3.
- Inch chart: lb/ft = π × (D − t) × t × 12 × 0.2865, with D and t in inches. For 1 in. × 0.065 in. the result is 0.656 lb/ft.
The two methods use slightly different densities, so a converted result will not match exactly. Use the mm to inches converter for size conversions.
EN ISO 1127 tolerance classes
The standard gives classes but does not say which applies to seamless or welded tube. The product standard or the purchase order states the class. In each class, the larger of the two values applies.
| Outside diameter class | Tolerance | Wall class | Tolerance |
|---|---|---|---|
| D1 | ±1.5 %, min ±0.75 mm | T1 | ±15 %, min ±0.6 mm |
| D2 | ±1.0 %, min ±0.5 mm | T2 | ±12.5 %, min ±0.4 mm |
| D3 | ±0.75 %, min ±0.3 mm | T3 | ±10 %, min ±0.2 mm |
| D4 | ±0.5 %, min ±0.1 mm | T4 | ±7.5 %, min ±0.15 mm |
| — | — | T5 | ±5 %, min ±0.1 mm |
What to specify when ordering
- Size: OD × wall, with the unit, and whether the wall is nominal or minimum.
- Standard and grade: for example ASTM A269 TP316L or EN 10216-5 1.4404.
- Type: seamless or welded. Very small sizes are in capillary tube.
- Tolerance class, length and quantity: A269 cut lengths up to 24 ft (7.3 m) allow plus 1/8 in. (3.2 mm) or 3/16 in. (4.8 mm) and no minus, depending on OD.
Send your OD, wall, standard and quantity to get a quote, or browse more charts in our technical resources.
Frequently asked questions
What sizes does stainless steel tube come in?
EN ISO 1127 lists outside diameters from 6 mm to 1016 mm and walls from 1.0 to 14.2 mm, although not every combination has a listed mass. Inch tube is commonly ordered from 1/8 in. upward by actual OD and wall.
How do you read a tube size?
A tube size gives the actual outside diameter and the wall thickness, such as 25.4 × 1.65 mm. The inside diameter is the OD minus twice the wall, which is 22.1 mm in this example.
Is 1/2 inch tube the same as 1/2 inch pipe?
No. A 1/2 in. tube has a 0.500 in. (12.70 mm) outside diameter, while NPS 1/2 pipe has a 0.840 in. (21.34 mm) outside diameter.
What is the OD tolerance on 1 inch stainless tube?
Under ASTM A269/A269M-25 Table 4, tube from 1/2 in. to under 1 1/2 in. OD has ±0.005 in. (±0.13 mm) on OD and ±10 % on wall, unless the wider wall limits in the table notes apply.
How much does stainless steel tube weigh?
Under EN ISO 1127 Table 3, 21.3 × 2.0 mm is 0.966 kg/m and 60.3 × 2.0 mm is 2.92 kg/m. By calculation at 7.93 g/cm³, 1 in. × 0.065 in. tube is about 0.66 lb/ft.
