Carbon Steel Round Tube Weight
Mass per metre and per foot for carbon steel round tube at 7,850 kg/m³ (ASTM A36 / AISI 1018 / EN 10025 S275). Every figure is for the section as drawn. A 6 m length of this size weighs 20.9 kg (46.7 lb per 20 ft).
At the reference dimensions (D = 50 mm, t = 3 mm) this section has a cross-sectional area of 443.0 mm², giving 3.477 kg/m (2.337 lb/ft). This is the baseline density, so the figures here are what a steel weight chart shows.
Round Tube — formula and derivation
Area of a round tube
A = π/4 · (D² − d²), d = D − 2t
A = π/4 × (D² − d²), where D is the outside diameter, d the inside diameter, and d = D − 2t for wall thickness t
Worked through with the default dimensions:
A = π/4 × (D² − d²)d = 50 − 2 × 3 = 44.0 mmA = 0.785398 × (50² − 44.0²)A = 0.785398 × 564.0A = 443.0 mm²
- D
- Outside diameter
- t
- Wall thickness — Must be less than half the outside diameter.
Weight follows from the area with no further geometry: m = A × 10⁻⁶ × ρ, where A is in mm², ρ in kg/m³ and m in kg/m. At 7,850 kg/m³ that is 3.4773 kg/m for the reference size above.
Carbon steel round tube — size series
| Outside diameter | 1.0 | 1.5 | 2.0 | 3.0 | 4.0 | 5.0 | 6.0 | 8.0 |
|---|---|---|---|---|---|---|---|---|
| 12 mm | 0.271 kg/m · 0.182 lb/ft | 0.388 kg/m · 0.261 lb/ft | 0.493 kg/m · 0.331 lb/ft | 0.666 kg/m · 0.447 lb/ft | 0.789 kg/m · 0.530 lb/ft | 0.863 kg/m · 0.580 lb/ft | 0.888 kg/m · 0.597 lb/ft | 0.789 kg/m · 0.530 lb/ft |
| 16 mm | 0.370 kg/m · 0.249 lb/ft | 0.536 kg/m · 0.360 lb/ft | 0.691 kg/m · 0.464 lb/ft | 0.962 kg/m · 0.646 lb/ft | 1.184 kg/m · 0.795 lb/ft | 1.356 kg/m · 0.911 lb/ft | 1.480 kg/m · 0.994 lb/ft | 1.578 kg/m · 1.061 lb/ft |
| 20 mm | 0.469 kg/m · 0.315 lb/ft | 0.684 kg/m · 0.460 lb/ft | 0.888 kg/m · 0.597 lb/ft | 1.258 kg/m · 0.845 lb/ft | 1.578 kg/m · 1.061 lb/ft | 1.850 kg/m · 1.243 lb/ft | 2.072 kg/m · 1.392 lb/ft | 2.368 kg/m · 1.591 lb/ft |
| 25 mm | 0.592 kg/m · 0.398 lb/ft | 0.869 kg/m · 0.584 lb/ft | 1.134 kg/m · 0.762 lb/ft | 1.628 kg/m · 1.094 lb/ft | 2.072 kg/m · 1.392 lb/ft | 2.466 kg/m · 1.657 lb/ft | 2.811 kg/m · 1.889 lb/ft | 3.354 kg/m · 2.254 lb/ft |
| 32 mm | 0.765 kg/m · 0.514 lb/ft | 1.128 kg/m · 0.758 lb/ft | 1.480 kg/m · 0.994 lb/ft | 2.146 kg/m · 1.442 lb/ft | 2.762 kg/m · 1.856 lb/ft | 3.329 kg/m · 2.237 lb/ft | 3.847 kg/m · 2.585 lb/ft | 4.735 kg/m · 3.182 lb/ft |
| 40 mm | 0.962 kg/m · 0.646 lb/ft | 1.424 kg/m · 0.957 lb/ft | 1.874 kg/m · 1.259 lb/ft | 2.737 kg/m · 1.839 lb/ft | 3.551 kg/m · 2.386 lb/ft | 4.316 kg/m · 2.900 lb/ft | 5.031 kg/m · 3.381 lb/ft | 6.313 kg/m · 4.242 lb/ft |
| 50 mm | 1.208 kg/m · 0.812 lb/ft | 1.794 kg/m · 1.206 lb/ft | 2.368 kg/m · 1.591 lb/ft | 3.477 kg/m · 2.337 lb/ft | 4.538 kg/m · 3.049 lb/ft | 5.549 kg/m · 3.729 lb/ft | 6.511 kg/m · 4.375 lb/ft | 8.286 kg/m · 5.568 lb/ft |
| 63 mm | 1.529 kg/m · 1.027 lb/ft | 2.275 kg/m · 1.529 lb/ft | 3.009 kg/m · 2.022 lb/ft | 4.439 kg/m · 2.983 lb/ft | 5.820 kg/m · 3.911 lb/ft | 7.152 kg/m · 4.806 lb/ft | 8.434 kg/m · 5.668 lb/ft | 10.851 kg/m · 7.292 lb/ft |
| 76 mm | 1.850 kg/m · 1.243 lb/ft | 2.756 kg/m · 1.852 lb/ft | 3.650 kg/m · 2.453 lb/ft | 5.401 kg/m · 3.629 lb/ft | 7.103 kg/m · 4.773 lb/ft | 8.755 kg/m · 5.883 lb/ft | 10.358 kg/m · 6.960 lb/ft | 13.416 kg/m · 9.015 lb/ft |
| 89 mm | 2.170 kg/m · 1.458 lb/ft | 3.237 kg/m · 2.175 lb/ft | 4.291 kg/m · 2.883 lb/ft | 6.363 kg/m · 4.276 lb/ft | 8.385 kg/m · 5.634 lb/ft | 10.358 kg/m · 6.960 lb/ft | 12.281 kg/m · 8.253 lb/ft | 15.981 kg/m · 10.739 lb/ft |
| 114 mm | 2.787 kg/m · 1.873 lb/ft | 4.162 kg/m · 2.796 lb/ft | 5.524 kg/m · 3.712 lb/ft | 8.212 kg/m · 5.518 lb/ft | 10.851 kg/m · 7.292 lb/ft | 13.441 kg/m · 9.032 lb/ft | 15.981 kg/m · 10.739 lb/ft | 20.913 kg/m · 14.053 lb/ft |
| 168 mm | 4.118 kg/m · 2.767 lb/ft | 6.159 kg/m · 4.139 lb/ft | 8.188 kg/m · 5.502 lb/ft | 12.207 kg/m · 8.203 lb/ft | 16.178 kg/m · 10.871 lb/ft | 20.099 kg/m · 13.506 lb/ft | 23.971 kg/m · 16.108 lb/ft | 31.567 kg/m · 21.212 lb/ft |
Rows: outside diameter (mm). Columns: wall thickness (mm). Computed for Carbon Steel at 7850 kg/m³.
| Outside diameter | 1.0 | 1.5 | 2.0 | 3.0 | 4.0 | 5.0 | 6.0 | 8.0 |
|---|---|---|---|---|---|---|---|---|
| 12 mm | 34.6 | 49.5 | 62.8 | 84.8 | 100.5 | 110.0 | 113.1 | 100.5 |
| 16 mm | 47.1 | 68.3 | 88.0 | 122.5 | 150.8 | 172.8 | 188.5 | 201.1 |
| 20 mm | 59.7 | 87.2 | 113.1 | 160.2 | 201.1 | 235.6 | 263.9 | 301.6 |
| 25 mm | 75.4 | 110.7 | 144.5 | 207.3 | 263.9 | 314.2 | 358.1 | 427.3 |
| 32 mm | 97.4 | 143.7 | 188.5 | 273.3 | 351.9 | 424.1 | 490.1 | 603.2 |
| 40 mm | 122.5 | 181.4 | 238.8 | 348.7 | 452.4 | 549.8 | 640.9 | 804.2 |
| 50 mm | 153.9 | 228.6 | 301.6 | 443.0 | 578.1 | 706.9 | 829.4 | 1,055.6 |
| 63 mm | 194.8 | 289.8 | 383.3 | 565.5 | 741.4 | 911.1 | 1,074.4 | 1,382.3 |
| 76 mm | 235.6 | 351.1 | 465.0 | 688.0 | 904.8 | 1,115.3 | 1,319.5 | 1,709.0 |
| 89 mm | 276.5 | 412.3 | 546.6 | 810.5 | 1,068.1 | 1,319.5 | 1,564.5 | 2,035.8 |
| 114 mm | 355.0 | 530.1 | 703.7 | 1,046.2 | 1,382.3 | 1,712.2 | 2,035.8 | 2,664.1 |
| 168 mm | 524.6 | 784.6 | 1,043.0 | 1,555.1 | 2,060.9 | 2,560.4 | 3,053.6 | 4,021.2 |
Area is a property of the geometry alone, so this table is the same for every material. It is what you enter into a stress calculation; the mass table is what you enter into an order.
Each row is one nominal size. Because the area is computed from your dimensions rather than read from a mill table, a non-standard size is just as accurate — put it into the calculator above rather than interpolating between rows.
The same round tube in every material
Geometry is fixed and only density changes, so this table is the whole material-selection question in one view. Carbon Steel is highlighted. The percentage column is against carbon steel, which is the figure most quotations are built on.
| Material | Density kg/m³ | lb/in³ | Mass / length kg/m | lb/ft | vs carbon steel |
|---|---|---|---|---|---|
| Carbon Steel | 7,850 | 0.2836 | 3.477 | 2.337 | +0.0 % |
| Stainless Steel 304 | 8,000 | 0.2890 | 3.544 | 2.381 | +1.9 % |
| Stainless Steel 316 | 8,000 | 0.2890 | 3.544 | 2.381 | +1.9 % |
| Stainless Steel 316L | 8,000 | 0.2890 | 3.544 | 2.381 | +1.9 % |
| Stainless Steel 430 | 7,700 | 0.2782 | 3.411 | 2.292 | -1.9 % |
| Aluminum 6061-T6 | 2,700 | 0.0975 | 1.196 | 0.804 | -65.6 % |
| Aluminum 5052-H32 | 2,680 | 0.0968 | 1.187 | 0.798 | -65.9 % |
| Aluminum 7075-T6 | 2,810 | 0.1015 | 1.245 | 0.836 | -64.2 % |
| Copper C11000 | 8,940 | 0.3230 | 3.960 | 2.661 | +13.9 % |
| Brass C36000 | 8,500 | 0.3071 | 3.765 | 2.530 | +8.3 % |
| Bronze C93200 | 8,800 | 0.3179 | 3.898 | 2.619 | +12.1 % |
| Titanium Grade 2 | 4,510 | 0.1629 | 1.998 | 1.342 | -42.5 % |
| Gray Cast Iron | 7,200 | 0.2601 | 3.189 | 2.143 | -8.3 % |
| Lead | 11,340 | 0.4097 | 5.023 | 3.375 | +44.5 % |
| Rigid PVC (Type I) | 1,400 | 0.0506 | 0.620 | 0.417 | -82.2 % |
| HDPE (PE 100) | 960 | 0.0347 | 0.425 | 0.286 | -87.8 % |
Same geometry throughout, so the only variable is density. Carbon steel is highlighted as the baseline.
A note on using this table for costing: mass is not price. Aluminium is roughly a third of steel's mass here, but per kilogram it costs several times more, so a straight swap rarely saves money — what it buys is reduced load on a structure or a vehicle.
About carbon steel
The baseline against which every other metal is compared. Mild and medium carbon steels sit at 7,850 kg/m³ across the usual structural and free-machining grades: A36 plate, 1018 shaft, S275JR section. Carbon content moves density so little over the 0.05–0.60 % range that one figure covers the family, which is why mill weight tables for "steel" almost always assume 7,850 kg/m³ (0.2836 lb/in³). Use this entry when the drawing says "steel" and no grade is called out.
- Density
- 7,850 kg/m³ = 0.2836 lb/in³ · 1.0000× carbon steel · typical spread ±1 %
- Specification
- ASTM A36 / AISI 1018 / EN 10025 S275
- Equivalents
- AISI 1018 · EN 1.0401 · JIS SS400 · GB Q235
- Typical uses
- Structural sections · Plate and bar stock · Fabricated weldments · Shafts and pins
Unprotected carbon steel corrodes at roughly 0.1 mm/year in a mild inland atmosphere and far faster in coastal or chemical service, so a corrosion allowance changes the mass you should order — not this density.
About round tube
Hollow sections are the most efficient way to buy stiffness by weight, and the numbers are stark: a 50 mm outside diameter tube with a 3 mm wall has the same area as a 22.6 mm solid bar — about 20 % of the mass — but its second moment of area is roughly 2.4 times larger. The catch is local: a thin wall buckles and dents long before it yields, so tube is chosen for stiffness and stability, never for where impact or crushing is expected.
Specified as outside diameter × wall thickness. State the standard (e.g. EN 10219) and whether the tube is welded or seamless.
Download this data
Carbon steel round tube — CSV
Both buttons below read the tables rendered on this page, so the file matches what you are looking at. The full catalogue — all 16 materials across all 10 sections — is on the downloads page.
Fields are quoted per RFC 4180, with a UTF-8 byte-order mark so Excel reads the mm² and · characters correctly. Blank lines separate the weight matrix from the area matrix.
Frequently asked questions
How much does carbon steel round tube weigh?
At the reference dimensions (D = 50 mm, t = 3 mm) a carbon steel round tube of this size weighs 3.477 kg/m, or 2.337 lb/ft. The table above lists the figure for every standard size so you can read your size directly instead of scaling.
How is the weight of round tube calculated?
Weight is cross-sectional area × length × density. For this shape the area is A = π/4 · (D² − d²), d = D − 2t. At the reference dimensions that gives 443.0 mm², and multiplying by carbon steel's density of 7,850 kg/m³ gives 3.477 kg/m. Nothing is looked up in a table — which is why a non-standard size is calculated just as accurately as a standard one.
Why does carbon steel weigh more or less than steel?
It is the 7,850 kg/m³ baseline that every other figure on this site is measured against. Density is the only variable: the cross-sectional area depends purely on geometry, so a round tube of the same dimensions has the same area in every material and the mass simply scales with density. In this case the ratio is 1.0000× carbon steel.
What is the cross-sectional area of a round tube?
The area depends only on the dimensions, not on the material, so it is identical whichever material you select: at the reference dimensions it is 443.0 mm² (0.6866 in²). That is the number you would enter into a stress or deflection calculation, and it is why changing material on this page never changes the area column.
Does a carbon steel round tube weigh the same as a carbon steel part of a different shape?
No, and the difference is larger than most people expect. At equal nominal size, a square bar is 27.3 % heavier than a round bar, and a hollow section is typically 60–80 % lighter than the solid bar it replaces. Weight follows area, and area changes faster than dimensions do — which is exactly why this needs calculating rather than estimating.
Other materials, same round tube
The same geometry in every material, so the only variable is density.
- SS 304 round tube — 8000 kg/m³
- SS 316 round tube — 8000 kg/m³
- AL 6061 round tube — 2700 kg/m³
- Copper round tube — 8940 kg/m³
- Brass round tube — 8500 kg/m³
- HDPE round tube — 960 kg/m³
- PVC round tube — 1400 kg/m³
- AL 5052 round tube — 2680 kg/m³
Other Carbon steel sections
The same density applied to every shape the site covers.
- Carbon steel round bar — A = π/4 · d²
- Carbon steel square bar — A = a²
- Carbon steel hexagonal bar — A = (√3/2) · AF² ≈ 0.8660 · AF²
- Carbon steel flat bar — A = w · t
- Carbon steel plate — A = w · t
- Carbon steel square tube — A = a² − (a − 2t)²
Reference data and tools
- Metal weight overview — how the calculation works
- All 16 materials — densities and specifications
- All 10 sections — formulas and size series
- Density chart — lightest to heaviest
- Metal weight calculator — any size, any material
- All calculators — metal weight and pipe weight
- Download the data — CSV, generated from the same source
- Cross-reference tables — DN / NPS / material equivalents
- Methodology and sources — where every number comes from
Round Tube area from A = π/4 · (D² − d²), d = D − 2t. Mass computed as area × length × density at 7,850 kg/m³ (ASTM A36 / AISI 1018 / EN 10025 S275). No weight on this page is copied from a published table — which is why figures can differ in the last significant digit from a mill's chart calculated at a nominal density.
- Elementary plane geometry. The circle, polygon and hollow-section area formulas.
- ASTM material specifications for each grade named in the material entry (A36, A240/A276, B209/B211/B221, B152/B16/B505, B265/B348, A48, B29, D1784, D3350).
- BIPM / NIST definitional constants: international inch = 25.4 mm, foot = 0.3048 m, pound = 0.45359237 kg.
Dataset version 2026.09.1 · dimensions last verified against source 2026-09-21. Found an error? Report it — corrections are issued with a version bump.