Calculate the weight of bars, rebar, plates, tubes, angles, channels, beams and tees in steel, stainless, aluminum, copper and 20+ other metals. Compare metals side by side, plan stock lengths and estimate material cost.
+ More options: waste, price, stock length
Theoretical weights use sharp corners and nominal sizes. Rolled sections with fillets, galvanizing and mill tolerances usually weigh a few percent more.
Metal Weight Calculation
Every metal weight calculation has the same three steps, whatever the shape:
- Find the cross-section area of the product from its dimensions (see the formulas below).
- Multiply by the length to get the volume.
- Multiply the volume by the density of the metal, keeping the units consistent.
Worked example with a labeled diagram
A carbon steel round bar with a 20 mm diameter and a length of 1 m:
Volume = 3.1416 cm² × 100 cm = 314.16 cm³
Weight = 314.16 cm³ × 7.85 g/cm³ = 2,466 g ≈ 2.47 kg (5.44 lb)
Shortcut for steel round bars: weight (kg/m) = d² ÷ 162, with d in mm. Check: 20² ÷ 162 = 2.47 kg/m.
Why different calculators give slightly different answers
- Density choice. Carbon steel is usually taken as 7.85 g/cm³ (7,850 kg/m³). Some tools use 7.80 or 7.95, which changes every result by 1–1.5%. Use the density from your mill certificate when you have it.
- Steel is not a pure metal. It is an alloy of iron and carbon, so stainless, tool and alloy steels each have their own density.
- Fillets and tolerances. A rolled IPE 200 beam has a catalog weight of about 22.4 kg/m, while the sharp-corner formula gives about 21.4 kg/m (roughly 4–5% less) because the formula ignores the root radius.
Need to total a long cut list? Add every member’s weight with the Summation Calculator, which accepts a pasted list of numbers.
Types of Metal Products Supported
The calculator handles 12 common product shapes. Measure the dimensions shown in the diagram below, enter them in any unit, and the tool converts everything for you.
| Product | Enter | Cross-section area |
|---|---|---|
| Round bar / rebar | Diameter D, length | π D² ÷ 4 |
| Square / rectangular bar | Width W, height H, length | W × H |
| Hexagonal bar | Across-flats A, length | 0.866 × A² |
| Plate / sheet | Length, width, thickness (or steel gauge) | Volume = L × W × T |
| Round tube / pipe | Outer diameter OD, wall t, length | π × t × (OD − t) |
| Square / rectangular tube | W, H, wall t, length | W×H − (W−2t)(H−2t) |
| Angle (L) | Legs a and b, thickness t, length | t × (a + b − t) |
| Channel (U / C) | Height h, flange b, web tw, flange tf | h × tw + 2 × tf × (b − tw) |
| I / H beam | Height h, flange b, web tw, flange tf | 2 × b × tf + (h − 2tf) × tw |
| T-section | Flange b, height h, tf, tw | b × tf + (h − tf) × tw |
| Known area | Area from a catalog or CAD, length | Entered directly |
Notes on each product
- Round bar and rebar: pick a rebar size to fill the nominal diameter and steel density automatically.
- Hex bar: the dimension is the distance between two parallel flats, not the corner-to-corner width.
- Plate and sheet: choose a steel gauge to fill the thickness. Gauge numbers differ between steel, stainless and aluminum, so use a measured thickness for non-steel sheet.
- Tube and pipe: uses the outer diameter and wall thickness. For pipe, take the actual OD and wall from the schedule table.
- Square tube: corner radii are ignored, so real weights run slightly lower than catalog values.
- Channel, I-beam and tee: treated as parallel-flange sections with no fillets. For tapered flanges (such as UPN or S-beams) use the catalog area through “Known area”.
Metal Density Table
| Metal / alloy | g/cm³ | kg/m³ | lb/in³ |
|---|---|---|---|
| Carbon steel | 7.85 | 7,850 | 0.284 |
| Stainless steel 304 / 316 | 8.00 | 8,000 | 0.289 |
| Cast iron | 7.20 | 7,200 | 0.260 |
| Aluminum 6061 | 2.70 | 2,700 | 0.098 |
| Copper | 8.96 | 8,960 | 0.324 |
| Brass | 8.50 | 8,500 | 0.307 |
| Bronze | 8.80 | 8,800 | 0.318 |
| Titanium (commercially pure) | 4.51 | 4,510 | 0.163 |
| Zinc | 7.14 | 7,140 | 0.258 |
| Lead | 11.34 | 11,340 | 0.410 |
| Nickel 200 | 8.89 | 8,890 | 0.321 |
| Magnesium | 1.74 | 1,740 | 0.063 |
Typical values. Exact density varies by alloy, temper and supplier by about 1–2%.
Because aluminum 6061 is about 34% as dense as carbon steel, the same shape in aluminum weighs roughly two-thirds less. Stainless 304 is about 2% heavier than carbon steel. The “compare metals” table in the results shows this for your own dimensions.
Quick Reference Weights
Plate weight per unit area
| Metal | kg per m² per 1 mm | lb per ft² per 1 in |
|---|---|---|
| Carbon steel | 7.85 | 40.8 |
| Stainless 304 | 8.00 | 41.6 |
| Aluminum 6061 | 2.70 | 14.0 |
| Copper | 8.96 | 46.6 |
| Brass | 8.50 | 44.2 |
| Titanium (CP) | 4.51 | 23.4 |
Steel rebar weight
| US bar | Diameter | lb per ft | Metric bar | kg per m |
|---|---|---|---|---|
| #3 | 0.375 in | 0.376 | 8 mm | 0.395 |
| #4 | 0.500 in | 0.668 | 10 mm | 0.617 |
| #5 | 0.625 in | 1.043 | 12 mm | 0.888 |
| #6 | 0.750 in | 1.502 | 16 mm | 1.578 |
| #8 | 1.000 in | 2.670 | 20 mm | 2.466 |
| #10 | 1.270 in | 4.303 | 25 mm | 3.853 |
Steel sheet gauge thickness
| Gauge | Thickness (in) | Thickness (mm) | lb per ft² |
|---|---|---|---|
| 7 | 0.1793 | 4.55 | 7.32 |
| 10 | 0.1345 | 3.42 | 5.49 |
| 12 | 0.1046 | 2.66 | 4.27 |
| 14 | 0.0747 | 1.90 | 3.05 |
| 16 | 0.0598 | 1.52 | 2.44 |
| 18 | 0.0478 | 1.21 | 1.95 |
| 20 | 0.0359 | 0.91 | 1.47 |
| 24 | 0.0239 | 0.61 | 0.98 |
Ordering and Planning Tips
- Buy by stock length. Enter the mill length (for example 6 m or 20 ft) in More options to see how many pieces fit per bar and how many bars to order, including saw kerf.
- Add a waste allowance of 3–10% for cuts, end trimming and mistakes.
- Know your unit. Metal is priced per kg, lb, cwt or ton. A US ton is 2,000 lb and a tonne is 1,000 kg, a mix-up covered in the ton vs tonne section of our Asphalt Calculator.
- Check lifting and transport limits. A 6 m, 200 mm I-beam weighs about 130 kg, which is too heavy to move by hand.
- Coatings add weight. Hot-dip galvanizing adds a few percent to steel; ask your galvanizer for an allowance.
Planning a renovation that involves a steel beam or lintel? See how the budget fits your income in the House Affordability Calculator. Structural repairs may also be financed through an FHA 203(k) renovation loan, which you can price with the FHA Loan Calculator.
Frequently Asked Questions
How do you calculate the weight of metal?
Multiply the cross-section area by the length to get volume, then multiply by the metal’s density. For a 20 mm steel round bar, 1 m long: 3.1416 cm² × 100 cm × 7.85 g/cm³ ≈ 2.47 kg.
What is the density of steel?
Carbon steel is typically 7.85 g/cm³, which equals 7,850 kg/m³ or 0.284 lb/in³. Stainless steel 304 and 316 are about 8.0 g/cm³.
How much does a steel plate weigh per square metre or square foot?
Steel plate weighs about 7.85 kg per square metre for each millimetre of thickness. In US units, it is about 40.8 lb per square foot for each inch of thickness, so a ¼ in plate is roughly 10.2 lb/ft².
How much does rebar weigh per foot or per metre?
A #4 (½ in) bar weighs about 0.668 lb per foot, and a #5 bar about 1.043 lb per foot. In metric, a 12 mm bar weighs about 0.888 kg per metre and a 16 mm bar about 1.578 kg per metre.
How do you calculate the weight of a pipe or tube?
Use area = π × wall thickness × (outer diameter − wall thickness), then multiply by length and density. Choose “Round tube / pipe” and enter the outer diameter and wall thickness.
Is aluminum much lighter than steel?
Yes. Aluminum 6061 has a density of about 2.70 g/cm³ against 7.85 for carbon steel, so the same shape weighs about two-thirds less. Open the compare table in the results to see it for your dimensions.
Why does my calculated weight differ from the supplier’s weight?
Suppliers use actual section areas that include rounded corners and fillets, mill tolerances and sometimes a different density. Differences of 1–5% are normal. For rolled beams, enter the catalog area in the “Known area” option.
Is stainless steel heavier than carbon steel?
Slightly. Stainless 304 at about 8.00 g/cm³ is roughly 2% denser than carbon steel at 7.85 g/cm³, so identical shapes weigh about 2% more in stainless.
More calculators: House Affordability · FHA Loan · Asphalt · Summation
Last updated: October 2026. Densities are typical values; always confirm with your supplier’s data sheet for critical work.