Rectangular Hollow Section Weight Calculator
Enter the external width of the rectangular hollow section.
Enter the external height of the rectangular hollow section.
Enter the thickness of the material.
Enter the total length of the section in meters.
Typical density for steel is 7850 kg/m³.
Calculated Weight
—Weight per Meter: — kg
Outer Volume: — m³
Steel Volume: — m³
The weight is calculated by finding the volume of steel in the hollow section and multiplying it by the material's density. Volume is derived from the outer dimensions and wall thickness.
What is Rectangular Hollow Section Weight?
The "Rectangular Hollow Section Weight" refers to the calculated mass of a structural steel tube with a rectangular cross-section. These sections are widely used in construction, engineering, and manufacturing due to their excellent strength-to-weight ratio, torsional rigidity, and ease of fabrication. Calculating their weight is crucial for several reasons: material procurement, structural load calculations, transportation logistics, and cost estimation. Essentially, it's the product of the volume of steel used in the section and the density of the steel itself.
Who should use this calculator? Engineers, architects, fabricators, construction managers, procurement specialists, and DIY enthusiasts involved in projects utilizing steel structures will find this tool invaluable. Anyone needing to determine the weight of rectangular hollow steel sections for purchasing, installation, or structural analysis benefits from an accurate weight calculation.
Common Misconceptions: One common misconception is that weight can be approximated simply by using external dimensions without accounting for the hollow core. Another is assuming a standard density for all steel types, which can lead to inaccuracies if specific alloys have different densities. This calculator addresses these by precisely calculating the steel volume and allowing for adjustable material density.
Rectangular Hollow Section Weight Formula and Mathematical Explanation
The calculation of the weight for a rectangular hollow section (RHS) involves determining the precise volume of steel used and then multiplying it by the material's density. The formula accounts for the outer dimensions and the wall thickness to calculate the net volume of steel.
Step-by-step derivation:
- Calculate the outer volume of the rectangular prism defined by the external dimensions:
Outer Volume = Outer Width × Outer Height × Length - Calculate the inner dimensions. Subtract twice the wall thickness from both the outer width and outer height:
Inner Width = Outer Width - 2 × Wall Thickness
Inner Height = Outer Height - 2 × Wall Thickness - Calculate the inner volume of the hollow space:
Inner Volume = Inner Width × Inner Height × Length - Calculate the volume of steel by subtracting the inner volume from the outer volume:
Steel Volume = Outer Volume - Inner Volume - Finally, calculate the total weight:
Total Weight = Steel Volume × Material Density
Note: All dimensions must be in consistent units (e.g., meters for volume calculation if density is in kg/m³). The calculator handles the unit conversions internally.
Variables Explained:
| Variable | Meaning | Unit | Typical Range / Notes |
|---|---|---|---|
| Outer Width (OW) | The external width of the rectangular section. | mm | e.g., 20 mm to 500 mm |
| Outer Height (OH) | The external height of the rectangular section. | mm | e.g., 20 mm to 500 mm |
| Wall Thickness (WT) | The thickness of the steel material forming the section walls. | mm | e.g., 1 mm to 25 mm |
| Length (L) | The total length of the hollow section. | m | e.g., 1 m to 12 m |
| Material Density (ρ) | The mass per unit volume of the material. | kg/m³ | Steel: ~7850 kg/m³; Aluminum: ~2700 kg/m³ |
| Outer Volume | The total volume enclosed by the external dimensions. | m³ | Derived |
| Inner Volume | The volume of the hollow space inside the section. | m³ | Derived |
| Steel Volume | The actual volume of the steel material. | m³ | Derived |
| Total Weight | The final calculated mass of the section. | kg | Calculated Result |
Practical Examples (Real-World Use Cases)
Example 1: Structural Steel Beam for a Small Project
A fabrication workshop needs to calculate the weight of a standard steel beam for a small canopy structure. They are using a Rectangular Hollow Section with the following specifications:
- Outer Width: 100 mm
- Outer Height: 50 mm
- Wall Thickness: 4 mm
- Length: 6 meters
- Material: Mild Steel (Density: 7850 kg/m³)
Calculation:
- Outer Volume = (0.100 m × 0.050 m × 6 m) = 0.03 m³
- Inner Width = 100 mm – 2 × 4 mm = 92 mm (0.092 m)
- Inner Height = 50 mm – 2 × 4 mm = 42 mm (0.042 m)
- Inner Volume = (0.092 m × 0.042 m × 6 m) = 0.023184 m³
- Steel Volume = 0.03 m³ – 0.023184 m³ = 0.006816 m³
- Total Weight = 0.006816 m³ × 7850 kg/m³ = 53.51 kg
- Weight per Meter = 53.51 kg / 6 m = 8.92 kg/m
Interpretation: This 6-meter length of RHS weighs approximately 53.51 kg. This information is vital for ordering the correct amount of steel, planning transportation, and ensuring the structural supports can handle the load.
Example 2: Decorative Steel Frame for Furniture
A furniture designer is creating a bespoke table frame using a thinner-walled RHS for a lighter, more modern aesthetic. The dimensions are:
- Outer Width: 40 mm
- Outer Height: 20 mm
- Wall Thickness: 2 mm
- Length: 3 meters (for one leg assembly)
- Material: Mild Steel (Density: 7850 kg/m³)
Calculation:
- Outer Volume = (0.040 m × 0.020 m × 3 m) = 0.0024 m³
- Inner Width = 40 mm – 2 × 2 mm = 36 mm (0.036 m)
- Inner Height = 20 mm – 2 × 2 mm = 16 mm (0.016 m)
- Inner Volume = (0.036 m × 0.016 m × 3 m) = 0.001728 m³
- Steel Volume = 0.0024 m³ – 0.001728 m³ = 0.000672 m³
- Total Weight = 0.000672 m³ × 7850 kg/m³ = 5.27 kg
- Weight per Meter = 5.27 kg / 3 m = 1.76 kg/m
Interpretation: Each leg assembly weighs about 5.27 kg. This helps in understanding the total weight of the furniture piece and ensuring it is manageable for assembly and placement. The relatively low weight per meter (1.76 kg/m) is characteristic of lighter gauge RHS.
How to Use This Rectangular Hollow Section Weight Calculator
Our Rectangular Hollow Section Weight Calculator is designed for simplicity and accuracy. Follow these steps to get your weight calculation:
- Enter Outer Dimensions: Input the 'Outer Width' and 'Outer Height' of your RHS in millimeters (mm).
- Specify Wall Thickness: Enter the 'Wall Thickness' of the steel in millimeters (mm).
- Define Length: Provide the total 'Length' of the section in meters (m).
- Set Material Density: The default density for steel (7850 kg/m³) is pre-filled. Adjust this value if you are calculating the weight for a different material like aluminum or a specific steel alloy with a known different density.
- Click 'Calculate Weight': Once all fields are populated, click the button.
How to Read Results:
- Total Weight: This is the primary result, displayed prominently in kilograms (kg), showing the total mass of the section.
- Weight per Meter: This intermediate value shows the weight of a one-meter length of the section, useful for quick comparisons and pricing.
- Outer Volume & Steel Volume: These values help understand the geometric properties and the actual amount of material used.
Decision-Making Guidance: Use the results to inform purchasing decisions, verify supplier quotes, plan lifting and handling procedures, and accurately calculate the dead load in structural designs. Compare the 'Weight per Meter' across different section sizes to find the most material-efficient option for your needs.
Key Factors That Affect Rectangular Hollow Section Weight Results
Several factors influence the final calculated weight of a rectangular hollow section. Understanding these helps in achieving the most accurate results:
- Outer Dimensions (Width & Height): These are the primary determinants of the overall volume occupied by the section. Larger dimensions directly lead to a higher potential weight, assuming other factors remain constant.
- Wall Thickness: This is critical. A thicker wall means more steel material is present, significantly increasing the section's weight. Even a small increase in thickness can add substantial mass over longer lengths. This is the core of the 'hollow' calculation – the difference between outer and inner volumes.
- Length of Section: Weight scales linearly with length. A longer piece of the same profile will weigh proportionally more. This is why 'weight per meter' is such a common and useful metric in the steel industry.
- Material Density: Different metals have different densities. While steel is typically around 7850 kg/m³, aluminum alloys are much lighter (around 2700 kg/m³). Using the correct density for the specific material being used is essential for accurate weight calculation.
- Manufacturing Tolerances: Real-world manufacturing involves slight variations. Wall thickness and dimensions might deviate slightly from the nominal values. While this calculator uses exact inputs, actual purchased steel may vary slightly in weight due to these tolerances, often within specified industry standards.
- Corner Radii: Hollow sections have rounded internal and external corners. This calculation assumes sharp corners for simplicity, which is standard practice for most engineering calculations where the deviation is minimal for typical wall thicknesses. For extremely precise calculations or very thick-walled sections, more complex geometry might be considered, but it's rarely necessary.
- Surface Coatings or Treatments: Galvanizing, painting, or other protective coatings add a small amount of weight. This calculator calculates the weight of the base steel material only. For critical weight-sensitive applications, the weight of coatings might need to be considered separately.
Frequently Asked Questions (FAQ)
Q1: What is the standard density of steel used in calculations?
A1: The standard density for mild steel is approximately 7850 kg/m³. This is the value pre-filled in the calculator, but it can be adjusted if you are working with different steel alloys or other materials.
Q2: Can this calculator be used for square hollow sections?
A2: Yes, a square hollow section is just a special case of a rectangular hollow section where the outer width and outer height are equal. Simply input the same value for both 'Outer Width' and 'Outer Height'.
Q3: What units should I use for input?
A3: The calculator expects 'Outer Width', 'Outer Height', and 'Wall Thickness' in millimeters (mm), and 'Length' in meters (m). The 'Material Density' should be in kilograms per cubic meter (kg/m³). The output will be in kilograms (kg).
Q4: How accurate is the calculation?
A4: The calculation is highly accurate based on the provided inputs and the standard formula for volume. Accuracy depends on the precision of your measurements and the correctness of the material density value you use. Manufacturing tolerances are not accounted for.
Q5: Does the calculator account for cuts or holes in the section?
A5: No, this calculator determines the weight of a solid, continuous rectangular hollow section based on its overall dimensions. Any modifications like cuts, holes, or welded attachments would alter the final weight and need to be calculated separately.
Q6: Can I calculate the weight for aluminum RHS?
A6: Yes, you can. Simply change the 'Material Density' input. For most aluminum alloys, a density of around 2700 kg/m³ is typical. Ensure you use the correct density for the specific aluminum alloy.
Q7: What is the difference between weight per meter and total weight?
A7: The 'Total Weight' is the mass of the entire length of the section you entered. The 'Weight per Meter' is the total weight divided by the length, giving you the weight of just one meter of that section. This is useful for comparing different sizes and for pricing.
Q8: Why is calculating RHS weight important for structural projects?
A8: Accurate weight is crucial for determining the dead load that a structure must support, ensuring foundations and supporting members are adequately designed. It's also vital for transportation logistics, material ordering, and cost management throughout the project lifecycle.
Weight Comparison by Wall Thickness
Weight per Meter (Outer Dim: 100x50mm) |
Weight per Meter (Outer Dim: 80x40mm)
Illustrates how weight per meter changes with wall thickness for two common RHS sizes.