Weight & material
Weight of round, tube, hex, square and flat bar for 27 materials. Plus the material requirement for a batch: blank length, parts per bar and how many bars to order.
Material requirement for a batch
Length L above is the finished length. Facing allowance and parting width are added. The remnant of each bar stays in the chuck or bar feeder.
Weights from nominal dimensions and nominal density. Rolling and drawing tolerances, corner radii on square and hex bar and density variation within an alloy are not taken into account, so the actual weight typically differs by a few percent. Material weight is calculated in whole bars.
Formulas at a glance
How to calculate weight
Cross-section A in mm², length L in mm, density ρ in g/cm³, result in kg. Example: round steel bar Ø30, 1 m long, gives 706.9 · 1000 · 7.85 / 1,000,000 = 5.549 kg.
Cross-section of round bar
For Ø30 that is 706.9 mm². For tube, the inner cross-section is subtracted, see below.
Cross-section of hex bar
AF is the dimension across flats. Hex AF30 in steel weighs 6.118 kg/m, a good 10 % more than round Ø30.
Cross-section of tube
D is the outer diameter, s the wall thickness. Tube 40 × 3 in steel has a cross-section of 348.7 mm² and weighs 2.737 kg/m.
Density of common materials
Nominal density at room temperature, each from at least two manufacturer or stockholder data sheets. Where sources differ, the value from the European data sheets applies.
| Material | Group | g/cm³ |
|---|---|---|
| S235JR (1.0038) | Steel | 7.85 |
| C45 (1.0503) | Steel | 7.85 |
| 42CrMo4 (1.7225) | Steel | 7.85 |
| 11SMnPb30 (1.0718) | Steel | 7.85 |
| X153CrMoV12 (1.2379) | Steel | 7.70 |
| 1.4301 (X5CrNi18-10) | Stainless steel | 7.90 |
| 1.4305 (X8CrNiS18-9) | Stainless steel | 7.90 |
| 1.4404 (X2CrNiMo17-12-2) | Stainless steel | 8.00 |
| 1.4571 (X6CrNiMoTi17-12-2) | Stainless steel | 8.00 |
| EN AW-6082 | Aluminium | 2.70 |
| EN AW-6060 | Aluminium | 2.70 |
| EN AW-7075 | Aluminium | 2.80 |
| EN AW-5083 | Aluminium | 2.66 |
| EN AW-2007 | Aluminium | 2.85 |
| CuZn39Pb3 (CW614N) | Copper & brass | 8.47 |
| Cu-ETP (CW004A) | Copper & brass | 8.93 |
| CuSn8 (CW453K) | Copper & brass | 8.80 |
| Ti Grade 2 (3.7035) | Titanium | 4.51 |
| Ti Grade 5 (3.7165) | Titanium | 4.43 |
| EN-GJL-250 | Cast iron | 7.20 |
| EN-GJS-400-15 | Cast iron | 7.10 |
| POM-C | Plastics | 1.41 |
| PA6 | Plastics | 1.14 |
| PEEK | Plastics | 1.31 |
| PTFE | Plastics | 2.15 |
| PE-HD | Plastics | 0.95 |
| PVC-U | Plastics | 1.44 |
Why weight matters in purchasing
Bar stock is sold by weight, not by length. To estimate the material cost of a batch you therefore need the weight per metre and the price per kilo. With stainless steel, brass and titanium, material is often the larger part of the part cost.
For a batch, what counts is not the weight of the finished part but that of the bars ordered. Every part needs facing allowance and parting width, and every bar leaves a remnant the bar feeder can no longer grip. With short parts, this loss quickly exceeds what is machined off the part.
From the shop floor: If each bar leaves a long remnant, it is worth asking for a different bar length. A length that divides exactly often gives one more part per bar. Over 2,000 parts that quickly means several bars fewer.
Frequently asked questions
How much does one metre of round steel bar weigh?
Cross-section times length times density. For round bar Ø30 at 7.85 g/cm³ that is 5.549 kg per metre. The rule of thumb for round steel: diameter in mm squared times 0.00617 gives kg per metre.
What is the density of stainless steel?
1.4301 (304) and 1.4305 (303) are 7.90 g/cm³, the molybdenum grades 1.4404 (316L) and 1.4571 (316Ti) 8.00 g/cm³. Stainless steel is therefore slightly heavier than mild steel at 7.85 g/cm³. One metre of round Ø30 in 1.4301 weighs 5.584 kg.
How much lighter is aluminium than steel?
Common aluminium alloys such as EN AW-6082 are 2.70 g/cm³, about a third of steel. One metre of round Ø30 weighs 1.909 kg in aluminium instead of 5.549 kg in steel. 7075 is slightly heavier at 2.80 g/cm³.
How do you calculate the weight of hex bar?
The cross-section is the square root of three over two times the across-flats dimension squared, roughly 0.866 times AF². Hex AF30 in steel has a cross-section of 779.4 mm² and weighs 6.118 kg per metre.
How many parts do I get from one bar?
Bar length minus remnant, divided by blank length, rounded down. The blank length is finished length plus facing allowance plus parting width. With 100 mm finished length, 1 mm facing allowance, 3 mm parting width, a 3 m bar and a 200 mm remnant that gives 26 parts, so 20 bars for 500 parts.
How accurate is the calculated weight?
The calculation uses nominal size and nominal density. Bar stock has dimensional tolerances, square and hex bar have rounded corners, and density varies slightly within an alloy. The real weight therefore typically differs by a few percent. That is accurate enough for purchasing, not for the scales.
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