Stainless steel tube is sized by its actual outside diameter and wall thickness, not by a nominal pipe size. A 1 in tube measures 1 in across the outside; a 1 in pipe does not. This chart lists the common stock sizes for 304 and 316 round tube with calculated weights, and explains which ASTM specification applies.
Stainless Tube vs Stainless Pipe
Tube is ordered as outside diameter plus wall, usually in gauge or decimal inches. Pipe is ordered as a nominal pipe size plus a schedule, and the outside diameter is fixed for each nominal size: 1 in pipe is 1.315 in outside. Tube is used for structure, handrail, machinery and instrumentation; pipe is used to carry fluids. Carbon steel equivalents are in the round steel tube sizes chart.
Round Stainless Tube Sizes and Weights (lb/ft)
Weight for 304 or 316 round tube, calculated from the tube geometry at 0.289 lb/in³. 316 is within about half a percent of 304, so the same figures cover both.
| OD (in) | 20 ga (0.035 in) | 18 ga (0.049 in) | 16 ga (0.065 in) | 14 ga (0.083 in) | 11 ga (0.12 in) | 1/4 in (0.25 in) |
|---|---|---|---|---|---|---|
| 0.25 | 0.08 | 0.11 | – | – | – | – |
| 0.375 | 0.13 | 0.17 | 0.22 | 0.26 | – | – |
| 0.5 | 0.18 | 0.24 | 0.31 | 0.38 | 0.50 | – |
| 0.625 | 0.22 | 0.31 | 0.40 | 0.49 | 0.66 | – |
| 0.75 | 0.27 | 0.37 | 0.49 | 0.60 | 0.82 | – |
| 1 | 0.37 | 0.51 | 0.66 | 0.83 | 1.15 | – |
| 1.25 | 0.46 | 0.64 | 0.84 | 1.06 | 1.48 | 2.72 |
| 1.5 | 0.56 | 0.77 | 1.02 | 1.28 | 1.80 | 3.40 |
| 2 | 0.75 | 1.04 | 1.37 | 1.73 | 2.46 | 4.77 |
| 2.5 | 0.94 | 1.31 | 1.72 | 2.19 | 3.11 | 6.13 |
| 3 | 1.13 | 1.58 | 2.08 | 2.64 | 3.77 | 7.49 |
| 4 | 1.51 | 2.11 | 2.79 | 3.54 | 5.07 | 10.21 |
Weight (lb/ft) = 10.90 × (OD − wall) × wall, in inches
Tube Gauge to Wall Thickness
Stainless tube gauges are not the same as sheet gauges. These are the wall thicknesses normally supplied:
| Gauge | Wall (in) | Wall (mm) |
|---|---|---|
| 22 ga | 0.028 | 0.71 |
| 20 ga | 0.035 | 0.89 |
| 18 ga | 0.049 | 1.24 |
| 16 ga | 0.065 | 1.65 |
| 14 ga | 0.083 | 2.11 |
| 12 ga | 0.109 | 2.77 |
| 11 ga | 0.12 | 3.05 |
| 1/8 in | 0.125 | 3.17 |
| 3/16 in | 0.1875 | 4.76 |
| 1/4 in | 0.25 | 6.35 |
304 vs 316
304 (UNS S30400) is the standard austenitic grade: 18% chromium, 8% nickel, 0.08% carbon maximum. It suits indoor and general outdoor use, food and beverage work and architectural jobs.
316 (UNS S31600) adds molybdenum, which improves resistance to chlorides, so it is the choice for coastal and marine exposure, pools, de-icing salt and many chemicals. It costs more.
The L grades, 304L and 316L, hold carbon to 0.035% maximum, which reduces the risk of sensitization when welding thicker sections.
Grade chemistry limits are from ASTM A269-04, Table 1.
Which ASTM Specification?
ASTM A269 covers seamless and welded austenitic stainless tubing for general service. It notes that sizes usually furnished are 1/4 in inside diameter and larger, with a wall of 0.020 in and heavier.
ASTM A554 covers welded stainless mechanical tubing, which is the specification behind most ornamental, handrail and structural tube with a polished finish.
ASTM A312 covers seamless and welded austenitic stainless pipe for pressure service, in nominal pipe sizes and schedules.
Size Tolerances
A269 allows the wall thickness to vary ±10% for tube 1/2 in and larger, and ±15% under 1/2 in. Outside diameter tolerance is ±0.005 in up to 1-1/2 in, ±0.010 in from 1-1/2 to 3-1/2 in, ±0.015 in from 3-1/2 to 5-1/2 in and ±0.030 in from 5-1/2 to 8 in. Thin-wall tube is also allowed some ovality, so measure both diameters when fit matters.
Source: ASTM A269-04, Section 1 and Table 3. Buy the current edition of the standard for design work.
Stainless Tube FAQ
How much does stainless tube weigh per foot?
Multiply (OD − wall) × wall × 10.90. A 1 in tube with a 16 gauge (0.065 in) wall weighs about 0.66 lb/ft; a 2 in tube with a 1/8 in wall weighs about 2.55 lb/ft.
Is 1 in stainless tube the same as 1 in pipe?
No. The tube is 1.000 in outside diameter. 1 in pipe is 1.315 in outside diameter.
What wall is 16 gauge stainless tube?
0.065 in, which is 1.65 mm. 14 gauge is 0.083 in and 11 gauge is 0.120 in.
Can I use these weights for square stainless tube?
No, the geometry differs. Use the steel tubing weight calculator for square and rectangular shapes and add about 2% for stainless.
This page is reference information only and is not engineering advice. Sizing, rigging and load capacity decisions need a qualified engineer. Full disclaimer.