Instantly estimate the weight and material cost of hollow metal bars, tubes, and pipes. Ideal for engineering procurement, logistics planning, and cost analysis.
Metric (mm, meters, kg)
Imperial (inches, feet, lb)
Select your preferred measurement units.
Steel (Carbon) – ~7850 kg/m³
Stainless Steel (304) – ~7900 kg/m³
Stainless Steel (316) – ~8000 kg/m³
Aluminum (6061) – ~2700 kg/m³
Brass – ~8500 kg/m³
Copper – ~8960 kg/m³
Titanium – ~4500 kg/m³
Cast Iron – ~7200 kg/m³
Base density affects the final weight calculation.
Please enter a valid positive diameter.
Must be less than half of Outer Diameter.
Wall thickness is too large for this diameter.
Enter price per unit of weight to estimate total cost.
Total Estimated Weight
0.00 kg
Weight Per Meter/Foot
0.00
Cross-Section Area
0.00
Total Estimated Cost
$0.00
Logic Used:
Weight = Volume × Density.
Volume is calculated by subtracting the inner cylinder volume from the outer cylinder volume (π × L × (R² – r²)).
Specification
Value
Unit
Material Density
7850
kg/m³
Outer Dimensions
50
mm
Inner Dimensions
40
mm
Total Volume
0.00
m³
Table 1: Detailed specification breakdown of the current calculation.
Figure 1: Weight comparison between the calculated hollow bar and a solid bar of equivalent outer diameter.
What is a Hollow Bar Weight Calculator?
A hollow bar weight calculator is an essential engineering and procurement tool used to estimate the mass of cylindrical metal tubes, pipes, or bushings based on their dimensional properties and material density. Unlike simple geometric calculations, this tool integrates specific material densities—such as steel, aluminum, or brass—to provide precise weight figures critical for logistics, structural analysis, and cost estimation.
Engineers, metal fabricators, and purchasing managers use this calculator to determine shipping loads and raw material costs. A common misconception is that one can simply guess the weight of a hollow section by percentage; however, slight variations in wall thickness can drastically alter the total mass (and subsequently the cost) of a project. Using a precise hollow bar weight calculator eliminates this guesswork.
Hollow Bar Weight Calculator Formula and Explanation
The mathematics behind the hollow bar weight calculator involves calculating the volume of the material and multiplying it by its density. The geometric shape is technically an annulus (a ring shape) extruded over a length.
Step 1: Calculate Cross-Sectional Area
The area is the difference between the outer circle area and the inner circle area. Area = π × (R² – r²)
Where R is the Outer Radius and r is the Inner Radius.
Step 2: Calculate Volume Volume = Area × Length
Step 3: Calculate Weight Weight = Volume × Density
Variable
Meaning
Metric Unit
Imperial Unit
OD
Outer Diameter
mm
inches
WT
Wall Thickness
mm
inches
ID
Inner Diameter (OD – 2×WT)
mm
inches
ρ (Rho)
Material Density
kg/m³
lb/in³ or lb/ft³
Table 2: Variables used in the weight calculation formula.
Practical Examples (Real-World Use Cases)
Example 1: Steel Pipe for Construction
A construction manager needs to order 50 pieces of hollow structural steel sections for a support framework.
Material: Carbon Steel (Density ~7850 kg/m³)
Dimensions: 100mm OD, 5mm Wall Thickness
Length: 6 meters per piece
Quantity: 50 pieces
Using the hollow bar weight calculator, the manager finds that each pipe weighs approximately 70.3 kg. The total order weight is 3,515 kg. If steel costs $1.20 per kg, the estimated material cost is $4,218. This precise figure allows for accurate budget allocation.
Example 2: Aluminum Bushing Stock
A machine shop is turning custom bushings from 6061 Aluminum hollow bars.
Material: Aluminum 6061 (Density ~2700 kg/m³)
Dimensions: 3 inch OD, 0.5 inch Wall Thickness
Length: 12 feet
The calculator determines the weight is roughly 55.4 lbs per bar. Knowing this weight helps the machinist ensure the lathe is rated for the stock weight and helps logistics calculate shipping via standard ground carriers versus freight.
How to Use This Hollow Bar Weight Calculator
Getting accurate results from this tool is straightforward. Follow these steps for the best results:
Select Unit System: Toggle between Metric (mm/kg) and Imperial (inch/lb) based on your supplier's specs.
Choose Material: Select the metal type from the dropdown. This sets the density automatically.
Input Dimensions: Enter the Outer Diameter (OD) and Wall Thickness. The tool calculates the Inner Diameter (ID) automatically.
Set Quantity: Enter the length per bar and the total number of bars required.
Review Cost (Optional): If you know the price per kg or lb, enter it to get a financial estimate.
The "Results" panel will update instantly. Use the "Copy Results" button to paste the data directly into your purchase order email or Excel sheet.
Key Factors That Affect Hollow Bar Weight Results
While the math is exact, real-world factors can influence the final calculation of your hollow bar weight calculator results.
Manufacturing Tolerances: Seamless and welded pipes have allowable tolerances (ASTM/ISO). A nominal 5mm wall might actually be 5.2mm, increasing weight by 4-5%.
Material Grade Variations: "Steel" is a broad term. Stainless steel (304 vs 316) has slightly different densities due to alloying elements like molybdenum.
Coatings and Linings: Galvanization or paint adds weight that is not accounted for in a pure geometric volume calculation.
Corner Radii (Rectangular): While this calculator focuses on round bars, if calculating for rectangular hollow sections (RHS), corner radii reduce the volume compared to a perfect rectangle.
Temperature: Metals expand with heat. While negligible for weight (mass remains constant), volume changes can affect fitment, though weight for shipping remains the same.
Scrap & Cut Loss: From a financial perspective, you must account for the kerf (material lost during cutting). Always order 5-10% more weight than the theoretical net weight.
Frequently Asked Questions (FAQ)
1. Can I use this for plastic or PVC pipes?
Yes, but you must know the density of the specific plastic. While the preset dropdowns cover metals, the formula applies to any material if the density is correct.
2. What is the difference between Pipe and Tube for weight?
The math is the same, but the sizing standards differ. Pipes are measured by Nominal Pipe Size (NPS), which doesn't always match the actual OD. Tubes are measured by exact OD. Always measure the physical OD for this hollow bar weight calculator.
3. Why is the Wall Thickness important?
Since the volume is calculated based on the area of the annulus, the wall thickness has a non-linear impact. Doubling the wall thickness often more than doubles the weight because you are adding material at the widest part of the circle.
4. Does this calculator account for welded seams?
No, it assumes a perfect geometric cylinder. Welded pipes may have a small weld bead that adds a negligible amount of weight, usually within standard tolerance limits.
5. How accurate is the cost estimation?
The cost is a theoretical estimate based on raw weight. It does not include processing fees, shipping, taxes, or surcharges often applied by metal suppliers.
6. Is the Inner Diameter (ID) calculated automatically?
Yes. By inputting OD and Wall Thickness, the calculator derives the ID ($ID = OD – 2 \times WT$). This ensures the geometry is physically possible.
7. Can I calculate for square hollow bars?
This specific tool is optimized for round hollow bars. Square bars require a formula using Width, Height, and Wall Thickness.
8. What if my Wall Thickness is half the Diameter?
If Wall Thickness is half the Outer Diameter, the Inner Diameter becomes zero, meaning it is a solid bar. The calculator will validate this limits.
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