Online Metal Weight Calculator
Select a metal and stock shape, enter its dimensions and quantity, and instantly calculate theoretical weight per piece, total weight, and weight per length.
Calculator is for informational purposes only. Terms and Conditions
This is a theoretical geometry × density calculation; actual stock weight can differ because of material composition, mill tolerances, corner radii, scale, and coatings.
Choose the metal and enter dimensions
The dimension fields change with the selected shape. Existing values are converted when units change.
Metal weight result
Theoretical weight based on ideal geometry and the active density.
Result details
- Check—
Show calculation stepsReview geometry, density, substitutions, conversions, and checks
- Enter valid values to see the complete calculation.
Selected shape diagram
Dimension symbols correspond to the active input fields.
Method, Sources, and Assumptions
Reference densities, calculation scope, and limitations.
Mass is calculated from idealized geometric volume and density. Preset densities are reference values; a custom density can be entered for supplier-specific material.
- Preset density applies to listed materials; Custom material requires a user-entered density.
- Tube and angle geometry is idealized with uniform thickness and sharp corners.
- For purchasing or critical lifting/shipping decisions, verify actual section weight and material data with the supplier.
Calculator guide
How the Online Metal Weight Calculator Works
The online metal weight calculator determines the theoretical mass of metal stock from the selected material, stock shape, dimensions, and quantity. It first calculates the volume of the solid metal, then multiplies that volume by material density. For constant cross-sections such as bar, tube, and angle, the same relationship can be written as mass = density × cross-sectional area × length.
The calculator above supports plate or sheet, flat bar, round bar, square bar, hex bar, round tube or pipe, square tube, rectangular tube, angle, round disc, and ring or washer. Results can be displayed in kilograms, pounds, metric tonnes, or short tons; length-based shapes also return kg/m and lb/ft.
- Minimum inputs
- Material, shape, required dimensions, and quantity.
- Primary output
- Total theoretical metal weight, or order weight when overage is applied.
- Core relationship
- Metal mass equals material density multiplied by metal volume.
How to Use the Metal Weight Calculator
Start with the material and stock profile, then enter only the dimensions shown for that shape. The calculator updates automatically as valid values change, so there is no separate Calculate button.
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Select the material and shape
Choose carbon or structural steel, 304L stainless steel, 316L stainless steel, aluminum 6061-T6, copper, titanium Grade 5, or Custom material. Then choose the stock shape that matches the actual cross-section.
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Enter the real dimensions
Use actual outside dimensions for the selected profile. For hollow tube or pipe, enter outside size and wall thickness. For hex bar, use the across-flats dimension. For a ring or washer, use outside diameter, inside diameter, and thickness.
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Choose units without changing the physical size
The U.S. Customary and Metric / SI selections convert the entered dimensions rather than simply relabeling them. Individual dimension units can also be changed where offered.
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Set quantity and review the result details
Quantity is the number of identical pieces. The result panel shows weight per piece, total weight in kg and lb, volume per piece, density used, and—when the shape has a length input—weight per meter and weight per foot.
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Use Advanced Options only when needed
Waste / Overage adds an ordering allowance, Material Price estimates cost from order weight, Answer Units changes the primary display unit, and Displayed Precision controls rounding. If the selected material is Custom material, enter the density supplied for that material.
Metal Weight Formulas by Shape
Every shape uses the same physics: calculate the volume occupied by metal and multiply by density. What changes from one stock profile to another is the geometry used to find volume or cross-sectional area.
General metal weight formula
Plain language: mass equals density multiplied by the volume of metal.
For a constant cross-section with area \(A\) and length \(L\), volume is \(V=AL\), so \(m=\rho AL\). Use one internally consistent unit system before multiplying.
- \(m\)
- Metal mass, reported by the calculator in kg, lb, tonnes, or short tons.
- \(\rho\)
- Material density, with kg/m³ as the calculator’s internal density basis.
- \(V\)
- Volume of solid metal, excluding hollow portions of tube, pipe, and rings.
- \(A\)
- Cross-sectional area of a constant-section bar, tube, pipe, or angle.
- \(L\)
- Piece length along the stock.
- \(t\)
- Plate thickness, wall thickness, or section thickness as applicable.
| Shape | Metal volume or mass relationship | Dimension meaning |
|---|---|---|
| Plate / Sheet | \(m=\rho Lwt\) | \(L\) length, \(w\) width, \(t\) thickness. |
| Flat Bar | \(m=\rho Lwt\) | \(L\) length, \(w\) width, \(t\) thickness. |
| Round Bar / Rod | \(m=\rho L\left(\frac{\pi D^2}{4}\right)\) | \(D\) is the solid bar diameter. |
| Square Bar | \(m=\rho La^2\) | \(a\) is the side length. |
| Hex Bar | \(m=\rho L\left(\frac{\sqrt{3}}{2}F^2\right)\) | \(F\) is measured across opposite flat faces. |
| Round Tube / Pipe | \(m=\rho L\left[\frac{\pi}{4}\left(D_o^2-(D_o-2t)^2\right)\right]\) | \(D_o\) outside diameter; inner diameter is \(D_o-2t\). |
| Square Tube | \(m=\rho L\left[a^2-(a-2t)^2\right]\) | \(a\) outside side length, \(t\) wall thickness. |
| Rectangular Tube | \(m=\rho L\left[wh-(w-2t)(h-2t)\right]\) | \(w\) and \(h\) are outside dimensions. |
| Angle | \(m=\rho L\left[t(a+b-t)\right]\) | \(a\) and \(b\) are leg lengths; the model uses uniform thickness \(t\). |
| Round Disc | \(m=\rho t\left(\frac{\pi D^2}{4}\right)\) | \(D\) diameter, \(t\) disc thickness. |
| Ring / Washer | \(m=\rho t\left[\frac{\pi}{4}\left(D_o^2-D_i^2\right)\right]\) | \(D_o\) outside diameter and \(D_i\) inside diameter. |
Weight per foot or per meter
For any constant-section stock, mass per unit length depends on only density and cross-sectional area:
This is why changing the piece length changes total piece weight but not kg/m or lb/ft. For example, doubling the length of the same round bar doubles piece weight while leaving its unit weight unchanged.
Quick check for carbon-steel plate
Using the calculator’s carbon-steel density of approximately 7,850 kg/m³, plate mass per square meter can be checked quickly when thickness \(t\) is in millimeters:
For example, a 10 mm carbon-steel plate is approximately \(7.85(10)=78.5\ \mathrm{kg/m^2}\). This shortcut is a density-specific check, not a replacement for the general formula when another material is selected.
Quick check for carbon-steel round bar
For a solid carbon-steel round bar with diameter \(D\) in millimeters, the calculator’s 7,850 kg/m³ density gives the useful approximation:
A 25 mm steel round bar therefore weighs approximately \(25^2/162.2=3.85\ \mathrm{kg/m}\), which provides a quick independent check of the live result.
Metal Density Reference Values
Density controls how much a given metal volume weighs. The calculator uses the following reference presets; they are appropriate for theoretical estimating, while supplier or material-certificate density should be used when a project requires a specific product value.
| Material | Density (kg/m³) | Approx. density (g/cm³) | Source basis |
|---|---|---|---|
| Carbon / Structural Steel | 7,850 | 7.85 | SSAB steel reference |
| Stainless Steel 304L | 8,000 | 8.00 | Alfa Laval 304L physical-property reference |
| Stainless Steel 316L | 8,000 | 8.00 | Alleima 316/316L material data |
| Aluminum 6061-T6 | 2,700 | 2.70 | Kaiser Aluminum 6061 reference |
| Copper | 8,960 | 8.96 | NIST elemental copper reference |
| Titanium Grade 5 / Ti-6Al-4V | 4,430 | 4.43 | CERN Ti-6Al-4V material-property reference |
The authoritative reference basis for each preset is documented in Sources and Calculation Verification.
How different metals compare at the same volume
When geometry is held constant, mass changes directly with density. Relative to the calculator’s carbon-steel preset, equal-volume 6061-T6 aluminum has about \(2700/7850\approx0.344\), or 34.4%, of the theoretical mass. Copper has about \(8960/7850\approx1.142\), or 114.2%, of the theoretical mass of the same-volume carbon-steel part.
Worked Example: Steel Plate Weight
Consider the calculator’s default example: one carbon-steel plate measuring 96 in × 48 in × 0.25 in, using the 7,850 kg/m³ carbon-steel density preset. This example is useful because the geometry can be checked independently in either U.S. or SI units.
Calculate the plate volume
Multiply volume by steel density
Result
148.19 kg ≈ 326.7 lb
With quantity 1 and 0% overage, the total theoretical weight is the same as the per-piece weight.
How to Interpret the Results
Treat the primary value as a theoretical mass estimate for the entered geometry and density. Use the secondary outputs to check whether the number is reasonable before using it for purchasing, shipping, fabrication planning, or another downstream estimate.
Weight per piece vs. total weight
Weight per piece is the calculated mass of one item. Total weight is that value multiplied by quantity. With identical pieces, doubling quantity doubles total weight exactly.
Weight per length
For bar, tube, pipe, and angle, kg/m and lb/ft depend on density and cross-sectional area, not on piece length. If changing only length also changed unit weight, recheck the entered geometry or units.
Density sensitivity
With geometry and quantity held constant, calculated mass changes in direct proportion to density. A 10% higher density produces a 10% higher theoretical mass.
Waste / overage and order weight
When overage is greater than zero, the calculator changes the primary result from net total weight to order weight using:
Here, \(w\) is the waste or overage percentage. A 5% overage does not make each finished part 5% heavier; it adds 5% to the material quantity used for ordering or estimating.
Material cost
If Material Price is entered, estimated cost is based on the calculated order weight and the selected $/kg or $/lb price. It is a material-only estimate from the price you enter; it does not supply live commodity pricing or automatically include freight, tax, cutting, machining, finishing, or supplier minimum charges.
How to Measure Metal Shapes Correctly
Most large errors in a geometry-based metal weight calculation come from using the wrong dimension convention rather than from the multiplication itself. Match the measurement to the shape definition used by the calculator.
Hex bar: use across flats
The hex-bar field \(F\) is the distance between two opposite flat faces. Do not substitute the across-corners dimension or the side length; those represent different regular-hexagon relationships.
Round tube / pipe: use actual OD
The model needs actual outside diameter and wall thickness. A nominal pipe designation is a naming convention and should not be entered as OD unless it is actually equal to the pipe’s outside diameter.
Square and rectangular tube: use outside size
Width, height, or side are outside dimensions. The calculator subtracts \(2t\) from each affected dimension to form the idealized hollow interior.
Ring / washer: distinguish OD and ID
Outside diameter defines the full disc area; inside diameter defines the removed center. The inside diameter must remain smaller than the outside diameter.
Angle: use leg dimensions and thickness
The calculator treats the angle as two rectangular legs of uniform thickness and subtracts the double-counted corner square. Rolled-section root and toe radii are not included in this idealized geometry.
Gauge is not a thickness unit
Do not enter a sheet-metal gauge number directly into a thickness field. Gauge is a material-dependent designation, not a dimensional unit, and the same gauge number can correspond to different thicknesses for steel, stainless steel, galvanized sheet, and aluminum. Convert the gauge to an actual thickness first.
Keep dimensions physically consistent
For hollow sections, wall thickness must leave a positive interior opening. A wall thickness equal to or greater than half of the relevant outside dimension is not valid for the model.
Theoretical Weight, Assumptions, and Accuracy
The calculator is an exact closed-form geometry calculation for its idealized shapes, but the real-world accuracy of the result depends on how closely the entered dimensions and density represent the actual product.
Uniform material density
The calculation assumes one density throughout the metal volume. Coatings, cladding, composite sections, voids, or mixed materials require separate treatment.
Ideal geometry
Plate, bars, discs, and rings use their nominal mathematical geometry. Tube and angle calculations assume uniform wall or section thickness. Corner radii, fillets, seams, and localized profile features are not added unless they are part of the entered ideal dimensions.
Nominal vs. actual dimensions
Mill and manufacturing tolerances mean an actual piece can be slightly thicker, thinner, larger, or smaller than its nominal size. Because volume is calculated from those dimensions, dimensional variation changes mass.
Standard structural sections
If a manufacturer or recognized section database publishes a unit weight for a named structural shape, that published value can better represent rolled fillets and profile details than rebuilding the section from simplified sharp-corner dimensions.
Density variation
The built-in densities are reference presets, not certified values for every heat, product form, or supplier. A specific supplier value can be entered with Custom material when tighter agreement is required.
Mass is not strength or capacity
A correct metal weight does not determine beam strength, lifting capacity, pipe pressure rating, stability, connection capacity, freight class, or code compliance. Those require separate inputs and methods.
Sources and Calculation Verification
The geometry formulas are derived from standard areas and volumes, while density and unit-conversion claims are checked against authoritative technical references. The worked example was recomputed independently in both SI and U.S. customary units.
- SSAB — 20 questions about steel — supports a steel density of 7.85 g/cm³, equivalent to 7,850 kg/m³.
- Alfa Laval — EN 1.4307 / AISI 304L — provides an 8,000 kg/m³ physical-property density for 304L.
- Alleima — Sanmac 316/316L — gives 316/316L density of 8.0 g/cm³, equivalent to 8,000 kg/m³.
- Kaiser Aluminum — Alloy 6061 rod and bar technical data — gives nominal 6061 density of 2.70 Mg/m³ at 20 °C.
- NIST — elemental copper composition — gives copper density of 8.960 g/cm³.
- CERN — Ti-6Al-4V material data — reports Ti-6Al-4V density of 4,430 kg/m³ at 20 °C in the cited material dataset.
- NIST Guide to the SI — conversion factors — supports the avoirdupois pound-to-kilogram conversion used for independent unit checks.
How the calculation was checked: the plate example was first solved in meters and kilograms using \(m=\rho Lwt\), then independently solved from 1,152 in³ and the converted steel density in lb/in³. Both paths give approximately 326.7 lb.
Frequently Asked Questions
These questions cover common cases that need an additional decision beyond the main calculator workflow.
Can I enter sheet-metal gauge instead of thickness?
No. The calculator requires an actual thickness dimension, not a gauge designation. Gauge-to-thickness relationships depend on the material, so convert the gauge first with the Sheet Metal Gauge Chart, then enter that thickness in the calculator.
Can the calculator estimate an irregular metal part?
Not directly unless the irregular part can be represented by one of the supported shapes. For a complex part, determine its material volume from CAD or divide it into simpler volumes, subtract holes or voids, then multiply the net volume by density.
Should I use calculated geometry or a published section weight?
Use idealized geometry when the entered dimensions accurately describe the stock you need to estimate. For a named commercial structural section, a current supplier or recognized section-table unit weight is often preferable because it can account for rolled fillets and profile details omitted by a sharp-corner model.
What should I do if I know the material mass and volume but not its density?
Calculate density first from \(\rho=m/V\), then enter that value with Custom material. The Density Calculator can perform that calculation when mass and volume are known.