Round Bar Weight Calculator
Enter round-bar diameter, stock length, quantity, and material to calculate theoretical weight. Use ordered blank dimensions for purchasing and finished dimensions only when you need the mass of the finished cylindrical part.
Planning a purchase? See what to include in your enquiry
Use this checklist when asking a supplier for a quote. Mark anything you are unsure about for confirmation.
- Material
- Grade and any specified material standard.
- Dimensions
- Plate, pipe or bar; dimensions and units.
- Quantity
- Number of pieces, length per piece or required weight.
- Tolerances
- Permitted dimensional variation, if specified.
- Finish and processing
- Surface finish, delivery condition and cutting requirements.
- Delivery
- Destination and preferred arrival date.
Add any inspection-document or packaging requirements. Theoretical weight is for planning; confirm the billing basis with the supplier.
Formula
Round bar cross-sectional area = π × diameter² / 4.
Theoretical mass per bar = cross-sectional area × length × nominal density.
Total theoretical mass = mass per bar × quantity.
Because area changes with diameter squared, a small diameter change can produce a larger percentage change in mass.
Common examples
Load a calculated example, then adjust its dimensions or quantity.
| Example | Inputs | Calculated answer | Load example |
|---|---|---|---|
| General fabrication stockSteel round bar, 25 mm × 6 mFull stock lengths can be totaled before cutting, then compared with the required pieces and the remnant expected from each bar. | Material or alloy: Carbon steel; Shape: Round bar; Diameter: 25 mm; Length: 6 m; Quantity: 20 | Total theoretical weight459.457926 kg | |
| Shaft blank planningSteel round bar, 50 mm × 6 mOrdered shaft length should already include facing, workholding, and machining allowance when the weight is calculated. | Material or alloy: Carbon steel; Shape: Round bar; Diameter: 50 mm; Length: 6 m; Quantity: 12 | Total theoretical weight1,102.699021 kg | |
| Stainless steel 304Food-equipment components304 stainless round bar, 30 mm × 3 mA 304 stainless estimate assumes a smooth solid cylinder; confirm grade, finish, diameter tolerance, and required certification separately. | Material or alloy: Stainless steel 304; Shape: Round bar; Diameter: 30 mm; Length: 3 m; Quantity: 8 | Total theoretical weight134.020343 kg | |
| Prototype machining blank6061 aluminum round bar, 75 mm × 3 mAlloy-specific density and oversize stock dimensions give a more useful prototype estimate than finished-part dimensions alone. | Material or alloy: Aluminum 6061; Shape: Round bar; Diameter: 75 mm; Length: 3 m; Quantity: 6 | Total theoretical weight214.708223 kg | |
| Turned fittings productionC360 brass round bar, 20 mm × 3 mIncoming C360 bar weight supports material planning, while chip yield and finished fitting weight require separate production calculations. | Material or alloy: Brass C360; Shape: Round bar; Diameter: 20 mm; Length: 3 m; Quantity: 16 | Total theoretical weight128.17698 kg | |
| US machine-shop rack1018 round bar, 1 in × 12 ftMultiple 1018 bars can be totaled for rack and order planning, then checked against the receiving scale when required. | Material or alloy: Steel AISI 1018; Shape: Round bar; Diameter: 1 in; Length: 12 ft; Quantity: 24 | Total theoretical weight350.057589 kg | |
| Heat-treatment blank order4140 round bar, 2 in × 6 ftGrade condition and ordered oversize should be confirmed because heat treatment and machining change the finished part, not this geometry result. | Material or alloy: Steel AISI 4140; Shape: Round bar; Diameter: 2 in; Length: 6 ft; Quantity: 10 | Total theoretical weight291.343991 kg | |
| Stainless steel 316Corrosion-resistant parts316 stainless round bar, 1.5 in × 12 ftCold-finished and hot-finished 316 bar may use different tolerances, so retain the exact grade and density source with the estimate. | Material or alloy: Stainless steel 316; Shape: Round bar; Diameter: 1.5 in; Length: 12 ft; Quantity: 6 | Total theoretical weight200.910594 kg | |
| High-strength fixture blank7075 aluminum round bar, 3 in × 6 ftAerospace-grade 7075 stock still needs approved material data and traceability; this calculation supports handling and quote screening only. | Material or alloy: Aluminum 7075; Shape: Round bar; Diameter: 3 in; Length: 6 ft; Quantity: 4 | Total theoretical weight93.741597 kg | |
| High-value inventory checkGrade 2 titanium round bar, 1 in × 3 ftComparing calculated and measured titanium stock mass can reveal an input or identification problem, but it does not verify the material grade. | Material or alloy: Titanium Grade 2; Shape: Round bar; Diameter: 1 in; Length: 3 ft; Quantity: 5 | Total theoretical weight10.448166 kg |
Frequently asked questions
Do I enter finished part length or stock length?
Enter stock length for purchasing and handling. Finished length is appropriate only when calculating the theoretical mass of the finished cylindrical part.
Does the calculation include machining allowance?
Only when the allowance is included in the entered diameter or length. The calculator does not infer saw, turning, grinding, or heat-treatment allowances.
Can I use the formula for rebar?
Not as a substitute for a rebar standard mass table. Ribs, nominal diameter conventions, and standard tolerances require the applicable rebar data.
Why does diameter accuracy matter so much?
Round area is proportional to diameter squared. An input or unit error in diameter therefore has a larger effect on estimated mass than the same percentage error in length.
Sources
Circumference, Area and Volume (Opens in a new tab)
National Institute of Standards and Technology
- Supports
- Geometry or calculation formula
- Checked
NIST Guide to the SI, Appendix B.8 and footnotes (Opens in a new tab)
National Institute of Standards and Technology
- Supports
- Unit conversion
- Checked
Code of Standard Practice for Steel Buildings and Bridges (Opens in a new tab)
American Institute of Steel Construction
- Supports
- Material density
- Checked