Brass C36000 Square Tube Weight
Mass per metre and per foot for brass c36000 square tube at 8,500 kg/m³ (ASTM B16 (UNS C36000, free-cutting)). Every figure is for the section as drawn. A 6 m length of this size weighs 22.6 kg (50.7 lb per 20 ft).
At the reference dimensions (a = 40 mm, t = 3 mm) this section has a cross-sectional area of 444.0 mm², giving 3.774 kg/m (2.536 lb/ft). Against carbon steel's 7,850 kg/m³ that is +8.3 % — the same section in steel would be 3.485 kg/m.
Square Tube — formula and derivation
Area of a square tube
A = a² − (a − 2t)²
A = a² − (a − 2t)², which expands to A = 4t(a − t)
Worked through with the default dimensions:
A = a² − (a − 2t)²Inner side = 40 − 2 × 3 = 34.0 mmA = 40² − 34.0²A = 1600.0 − 1156.0A = 444.0 mm²
- a
- Side
- t
- Wall thickness
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 8,500 kg/m³ that is 3.7740 kg/m for the reference size above.
Brass square tube — size series
| Side | 1.5 | 2.0 | 3.0 | 4.0 | 5.0 | 6.0 |
|---|---|---|---|---|---|---|
| 15 mm | 0.688 kg/m · 0.463 lb/ft | 0.884 kg/m · 0.594 lb/ft | 1.224 kg/m · 0.822 lb/ft | 1.496 kg/m · 1.005 lb/ft | 1.700 kg/m · 1.142 lb/ft | 1.836 kg/m · 1.234 lb/ft |
| 20 mm | 0.944 kg/m · 0.634 lb/ft | 1.224 kg/m · 0.822 lb/ft | 1.734 kg/m · 1.165 lb/ft | 2.176 kg/m · 1.462 lb/ft | 2.550 kg/m · 1.714 lb/ft | 2.856 kg/m · 1.919 lb/ft |
| 25 mm | 1.198 kg/m · 0.805 lb/ft | 1.564 kg/m · 1.051 lb/ft | 2.244 kg/m · 1.508 lb/ft | 2.856 kg/m · 1.919 lb/ft | 3.400 kg/m · 2.285 lb/ft | 3.876 kg/m · 2.605 lb/ft |
| 30 mm | 1.453 kg/m · 0.977 lb/ft | 1.904 kg/m · 1.279 lb/ft | 2.754 kg/m · 1.851 lb/ft | 3.536 kg/m · 2.376 lb/ft | 4.250 kg/m · 2.856 lb/ft | 4.896 kg/m · 3.290 lb/ft |
| 40 mm | 1.963 kg/m · 1.319 lb/ft | 2.584 kg/m · 1.736 lb/ft | 3.774 kg/m · 2.536 lb/ft | 4.896 kg/m · 3.290 lb/ft | 5.950 kg/m · 3.998 lb/ft | 6.936 kg/m · 4.661 lb/ft |
| 50 mm | 2.473 kg/m · 1.662 lb/ft | 3.264 kg/m · 2.193 lb/ft | 4.794 kg/m · 3.221 lb/ft | 6.256 kg/m · 4.204 lb/ft | 7.650 kg/m · 5.141 lb/ft | 8.976 kg/m · 6.032 lb/ft |
| 60 mm | 2.983 kg/m · 2.005 lb/ft | 3.944 kg/m · 2.650 lb/ft | 5.814 kg/m · 3.907 lb/ft | 7.616 kg/m · 5.118 lb/ft | 9.350 kg/m · 6.283 lb/ft | 11.016 kg/m · 7.402 lb/ft |
| 80 mm | 4.003 kg/m · 2.690 lb/ft | 5.304 kg/m · 3.564 lb/ft | 7.854 kg/m · 5.278 lb/ft | 10.336 kg/m · 6.945 lb/ft | 12.750 kg/m · 8.568 lb/ft | 15.096 kg/m · 10.144 lb/ft |
| 100 mm | 5.023 kg/m · 3.376 lb/ft | 6.664 kg/m · 4.478 lb/ft | 9.894 kg/m · 6.648 lb/ft | 13.056 kg/m · 8.773 lb/ft | 16.150 kg/m · 10.852 lb/ft | 19.176 kg/m · 12.886 lb/ft |
Rows: side (mm). Columns: wall thickness (mm). Computed for Brass C36000 at 8500 kg/m³.
| Side | 1.5 | 2.0 | 3.0 | 4.0 | 5.0 | 6.0 |
|---|---|---|---|---|---|---|
| 15 mm | 81.0 | 104.0 | 144.0 | 176.0 | 200.0 | 216.0 |
| 20 mm | 111.0 | 144.0 | 204.0 | 256.0 | 300.0 | 336.0 |
| 25 mm | 141.0 | 184.0 | 264.0 | 336.0 | 400.0 | 456.0 |
| 30 mm | 171.0 | 224.0 | 324.0 | 416.0 | 500.0 | 576.0 |
| 40 mm | 231.0 | 304.0 | 444.0 | 576.0 | 700.0 | 816.0 |
| 50 mm | 291.0 | 384.0 | 564.0 | 736.0 | 900.0 | 1,056.0 |
| 60 mm | 351.0 | 464.0 | 684.0 | 896.0 | 1,100.0 | 1,296.0 |
| 80 mm | 471.0 | 624.0 | 924.0 | 1,216.0 | 1,500.0 | 1,776.0 |
| 100 mm | 591.0 | 784.0 | 1,164.0 | 1,536.0 | 1,900.0 | 2,256.0 |
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 square tube in every material
Geometry is fixed and only density changes, so this table is the whole material-selection question in one view. Brass C36000 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 | 3.485 | 2.342 | +0.0 % |
| Stainless Steel 304 | 8,000 | 0.2890 | 3.552 | 2.387 | +1.9 % |
| Stainless Steel 316 | 8,000 | 0.2890 | 3.552 | 2.387 | +1.9 % |
| Stainless Steel 316L | 8,000 | 0.2890 | 3.552 | 2.387 | +1.9 % |
| Stainless Steel 430 | 7,700 | 0.2782 | 3.419 | 2.297 | -1.9 % |
| Aluminum 6061-T6 | 2,700 | 0.0975 | 1.199 | 0.806 | -65.6 % |
| Aluminum 5052-H32 | 2,680 | 0.0968 | 1.190 | 0.800 | -65.9 % |
| Aluminum 7075-T6 | 2,810 | 0.1015 | 1.248 | 0.838 | -64.2 % |
| Copper C11000 | 8,940 | 0.3230 | 3.969 | 2.667 | +13.9 % |
| Brass C36000 | 8,500 | 0.3071 | 3.774 | 2.536 | +8.3 % |
| Bronze C93200 | 8,800 | 0.3179 | 3.907 | 2.626 | +12.1 % |
| Titanium Grade 2 | 4,510 | 0.1629 | 2.002 | 1.346 | -42.5 % |
| Gray Cast Iron | 7,200 | 0.2601 | 3.197 | 2.148 | -8.3 % |
| Lead | 11,340 | 0.4097 | 5.035 | 3.383 | +44.5 % |
| Rigid PVC (Type I) | 1,400 | 0.0506 | 0.622 | 0.418 | -82.2 % |
| HDPE (PE 100) | 960 | 0.0347 | 0.426 | 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 brass c36000
Free-cutting brass, roughly 61 % copper and 3 % lead, and by a wide margin the most machinable common metal — it machines at about three times the speed of 1018 steel with excellent finish. Density 8,500 kg/m³ puts it 8.3 % above carbon steel. The lead that makes it machine so well is also why it is restricted in potable-water contact under many national rules, which pushes fittings toward lead-free silicon or bismuth brasses with densities 0.5–1 % lower.
- Density
- 8,500 kg/m³ = 0.3071 lb/in³ · 1.0828× carbon steel · typical spread ±2 %
- Specification
- ASTM B16 (UNS C36000, free-cutting)
- Equivalents
- EN CW603N · JIS C3604 · GB HPb59-1
- Typical uses
- Fittings and valves · Instrument and clock parts · Electrical connectors · Decorative hardware
Lead content (typically 2.5–3.7 %) restricts use in potable water. Typical density range 8,400–8,700 kg/m³ by composition.
About square tube
Square tube expands cleanly to A = 4t(a − t), which makes the sensitivity obvious: for a given side, weight is almost exactly linear in wall thickness. Doubling a 2 mm wall to 4 mm adds about 1.9 times the mass, not twice, because the inner void shrinks as the wall grows. Its flat faces also make it the natural choice for welded frames and for anything that has to be drilled, tapped or bolted through a face — a round tube gives you only a tangent point where a square tube gives you a full flat.
Specified as side × wall thickness. Corner radii are standardised per EN 10219 and change the area slightly at heavier walls.
Download this data
Brass square 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 brass c36000 square tube weigh?
At the reference dimensions (a = 40 mm, t = 3 mm) a brass c36000 square tube of this size weighs 3.774 kg/m, or 2.536 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 square tube calculated?
Weight is cross-sectional area × length × density. For this shape the area is A = a² − (a − 2t)². At the reference dimensions that gives 444.0 mm², and multiplying by brass c36000's density of 8,500 kg/m³ gives 3.774 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 brass c36000 weigh more or less than steel?
It is heavier than carbon steel for the same section — about 8 % heavier at 8,500 kg/m³. Density is the only variable: the cross-sectional area depends purely on geometry, so a square 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 1.0828× carbon steel.
What is the cross-sectional area of a square 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 444.0 mm² (0.6882 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 brass square tube weigh the same as a brass 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.
Should I use Brass weight or carbon steel weight for costing?
Use the material you are actually buying. At 8,500 kg/m³ against carbon steel's 7,850 kg/m³, the same square tube differs by 8.3 % in mass. On a per-metre quote that is invisible; on a fabricated tonnage it is the difference between a margin and a loss. This page computes the steel figure as 3.485 kg/m for comparison.
Other materials, same square tube
The same geometry in every material, so the only variable is density.
- Carbon steel square tube — 7850 kg/m³
- SS 304 square tube — 8000 kg/m³
- SS 316 square tube — 8000 kg/m³
- AL 6061 square tube — 2700 kg/m³
- Copper square tube — 8940 kg/m³
- HDPE square tube — 960 kg/m³
- PVC square tube — 1400 kg/m³
- AL 5052 square tube — 2680 kg/m³
Other Brass sections
The same density applied to every shape the site covers.
- Brass round bar — A = π/4 · d²
- Brass square bar — A = a²
- Brass hexagonal bar — A = (√3/2) · AF² ≈ 0.8660 · AF²
- Brass flat bar — A = w · t
- Brass plate — A = w · t
- Brass round tube — A = π/4 · (D² − d²), d = D − 2t
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
Square Tube area from A = a² − (a − 2t)². Mass computed as area × length × density at 8,500 kg/m³ (ASTM B16 (UNS C36000, free-cutting)). 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.