Calculate the Weight of Rhs

Accurate Rectangular Hollow Section Weight & Surface Area Calculator

What is "Calculate the Weight of RHS"?

To calculate the weight of RHS is a critical task in structural engineering, logistics, and construction cost estimation. RHS, or Rectangular Hollow Section, is a popular type of steel profile characterized by its flat sides and hollow core. Knowing the exact weight of these sections is essential for ensuring structural integrity, determining crane requirements, and estimating shipping costs.

Engineers and fabricators frequently need to calculate the weight of RHS to determine dead loads in building structures. Unlike solid bars, the hollow nature of RHS provides an excellent strength-to-weight ratio, making it a preferred choice for columns, beams, and architectural frameworks. Miscalculating this weight can lead to logistical failures or structural safety concerns.

Calculate the Weight of RHS: Formula and Mathematical Explanation

The mathematics required to calculate the weight of RHS involves determining the volume of material used and multiplying it by the material's density. The cross-section is essentially a larger rectangle with a smaller rectangle subtracted from its center.

The Core Formula:

$$ Weight = (Area_{outer} – Area_{inner}) \times Length \times Density $$

Where:
$$ Area_{outer} = Width (B) \times Height (D) $$
$$ Area_{inner} = (Width – 2t) \times (Height – 2t) $$

Variables Table

Variable	Meaning	Unit	Typical Range
B	Outer Width	mm	20mm – 400mm
D	Outer Height	mm	20mm – 400mm
t	Wall Thickness	mm	1.6mm – 16mm
ρ (Rho)	Density	kg/m³	7850 (Steel)

Practical Examples (Real-World Use Cases)

Example 1: Structural Steel Column

Imagine you need to calculate the weight of RHS for a structural support column. You are using a standard mild steel section.

• Dimensions: 100mm x 50mm
• Thickness: 4.0mm
• Length: 3 meters
• Material: Steel (7850 kg/m³)

First, calculate the cross-sectional area (CSA).
Outer Area = $100 \times 50 = 5000 \text{ mm}^2$.
Inner Area = $(100 – 8) \times (50 – 8) = 92 \times 42 = 3864 \text{ mm}^2$.
Net Steel Area = $5000 – 3864 = 1136 \text{ mm}^2$.
Volume per meter = $1136 \text{ mm}^2 \times 1000 \text{ mm} = 1,136,000 \text{ mm}^3 = 0.001136 \text{ m}^3$.
Weight per meter = $0.001136 \times 7850 = 8.92 \text{ kg/m}$.
Total Weight: $8.92 \times 3 = 26.76 \text{ kg}$.

Example 2: Aluminum Framework

For a lightweight frame, you might choose Aluminum.

• Dimensions: 50mm x 25mm
• Thickness: 2.0mm
• Length: 6 meters
• Density: 2700 kg/m³

Using the tool to calculate the weight of RHS for this profile reveals a significantly lighter result due to the lower density of aluminum compared to steel. The calculation would show a weight of roughly 0.77 kg/m, totaling approximately 4.62 kg for the full length.

How to Use This Calculator

Our tool is designed to help you calculate the weight of RHS quickly and accurately. Follow these steps:

1. Select Material: Choose the material type (e.g., Mild Steel, Aluminum) from the dropdown. This sets the density automatically.
2. Enter Dimensions: Input the outer Width (B) and Height (D) in millimeters.
3. Set Thickness: Enter the wall thickness (t) in millimeters. Ensure the thickness is not greater than half the width or height.
4. Specify Length: Enter the total length of the tube in meters.
5. Quantity: If you are fabricating a batch, enter the number of pieces.
6. Analyze Results: View the Total Weight, Surface Area, and Weight per Meter instantly.

Key Factors That Affect Weight Calculation Results

When you calculate the weight of RHS, several factors influence the final number beyond simple geometry.

• Material Density: This is the most significant factor. Steel is nearly three times heavier than aluminum. Using the wrong density value will drastically skew your results.
• Corner Radii: In reality, RHS corners are rounded, not sharp. This calculator uses a nominal geometric calculation. Real-world weights might be slightly lower due to the missing material at the corners, or higher if the manufacturing tolerance allows for extra thickness.
• Manufacturing Tolerances: Steel mills produce sections within specific tolerance bands (e.g., EN 10219). Thickness can vary by +/- 5%, affecting the actual weight compared to the theoretical weight.
• Surface Treatments: Galvanizing or painting adds weight. Hot-dip galvanizing can add approximately 0.3 to 0.5 kg/m² to the surface area weight, which should be factored in for precise shipping calculations.
• Length Accuracy: Cutting tolerances (e.g., +/- 2mm) usually have a negligible effect on weight but are crucial for fit-up.
• Material Composition: While "Steel" is generally 7850 kg/m³, specific alloys like stainless steel (approx 8000 kg/m³) are denser. Always verify the specific alloy grade.

Frequently Asked Questions (FAQ)

Does this calculator account for the corner radius?

This tool uses a standard geometric subtraction method (Outer Prism – Inner Prism). While it provides a highly accurate estimate (usually within 1-2%), strictly defined structural tables often apply a small correction factor for the mass of the corner radii.

Why is the weight important for RHS?

When you calculate the weight of RHS, you are determining the "dead load" of a structure. This is vital for safety calculations, transport logistics (truck capacity), and cost estimation, as steel is often sold by weight.

Can I calculate the weight of RHS for stainless steel?

Yes, simply select "Stainless Steel" from the material dropdown menu. It uses a higher density (typically 8000 kg/m³) than mild steel.

What is the formula for kg/m?

The simplified formula for steel kg/m is approximately: $Area (cm^2) \times 0.785$. For more precision, calculate the volume of 1 meter and multiply by density.

How do I calculate the surface area for painting?

Our calculator provides the "Total Surface Area" result. This is calculated as $2 \times (Width + Height) \times Length$. This figure is essential for estimating paint or galvanizing costs.

What happens if my thickness is too high?

If the thickness exceeds half of the width or height, the inner hole would mathematically disappear or invert. The calculator validates this and will show an error if the thickness is physically impossible.

Is RHS the same as SHS?

RHS stands for Rectangular Hollow Section, while SHS stands for Square Hollow Section. You can use this tool for SHS by simply entering the same value for Width and Height.

What is the density of mild steel?

The standard density used to calculate the weight of RHS for mild steel is 7850 kg/m³.

Related Tools and Internal Resources

Enhance your engineering workflow with our other specialized calculators:

• SHS Weight Calculator – Calculate weights for Square Hollow Sections.
• Steel Density Charts – Reference densities for various alloys.
• Beam Load Estimator – Determine load capacities for your sections.
• Fabrication Cost Estimator – Estimate costs based on weight and complexity.
• Metric to Imperial Steel Converter – Switch between standard sizes effortlessly.
• Shipping Volume Calculator – Plan your logistics based on bundle dimensions.

Calculated Weight

' + wt.toLocaleString('en-US', {maximumFractionDigits:2}) + ' kg