Rectangular Tube Weight Calculator
Accurate Engineering Tool for Steel, Aluminum & Custom Metals
Calculate Tube Weight
Enter dimensions to instantly calculate total weight and linear density.
Metric (mm, meters, kg)
Imperial (inches, feet, lbs)
Select your preferred unit system.
Steel (Mild)
Stainless Steel (304/316)
Aluminum (6061)
Brass
Copper
Custom Density
Choose standard material or enter custom density.
Enter the specific density of your material.
The external width of the rectangular section.
Width must be greater than 2x thickness.
The external height of the rectangular section.
Height must be greater than 2x thickness.
Thickness of the tube wall.
Total length of the tube.
Number of pieces.
Total Weight
0.00 kg
Weight per Unit Length
0.00 kg/m
Cross-Sectional Area
0.00 mm²
Total Volume
0.00 cm³
Formula Used: Weight = (Outer Volume – Inner Volume) × Density
Specification Breakdown
| Parameter | Value |
|---|---|
| Material | – |
| Dimensions | – |
| Total Length | – |
| Single Piece Weight | – |
Material Weight Comparison
Comparison of your tube dimensions across different materials.
How to Calculate Weight of Rectangular Tube: The Complete Guide
Understanding how to calculate weight of rectangular tube is a fundamental skill for engineers, fabricators, and construction professionals. Whether you are estimating shipping costs, determining structural loads, or purchasing raw materials, accurate weight calculation is critical to project success. This guide explores the mathematics behind the calculation, practical examples, and the factors that influence the final weight of hollow structural sections (HSS).
What is Rectangular Tube Weight Calculation?
Rectangular tube weight calculation involves determining the mass of a hollow rectangular prism based on its physical dimensions and material density. Unlike solid bars, rectangular tubes (often referred to as Rectangular Hollow Sections or RHS) have a void in the center, which significantly reduces their weight while maintaining high structural rigidity.
This calculation is used by:
- Structural Engineers: To ensure load-bearing structures do not exceed dead load limits.
- Fabricators: To estimate material costs and lifting requirements.
- Logistics Managers: To plan shipping capacities and adhere to vehicle weight limits.
Rectangular Tube Weight Formula
To understand how to calculate weight of rectangular tube manually, you must first determine the volume of the material used and then multiply it by the material's density. The most accurate method is the "subtraction method."
Weight = (Outer Volume – Inner Volume) × Density
Mathematically, this is derived as follows:
- Calculate Outer Area ($A_{out}$): Width ($W$) × Height ($H$)
- Calculate Inner Area ($A_{in}$): (Width – 2×Thickness) × (Height – 2×Thickness)
- Calculate Cross-Sectional Area ($A_{cross}$): $A_{out} – A_{in}$
- Calculate Volume ($V$): $A_{cross} \times Length$
- Calculate Weight ($W$): $V \times Density$
Variable Definitions
| Variable | Meaning | Metric Unit | Imperial Unit |
|---|---|---|---|
| W | Outer Width | mm | inches |
| H | Outer Height | mm | inches |
| t | Wall Thickness | mm | inches |
| L | Length | meters | feet |
| ρ (Rho) | Density | kg/m³ | lbs/in³ |
Practical Examples
Example 1: Steel Rectangular Tube (Metric)
Let's calculate the weight of a mild steel tube with dimensions 100mm x 50mm x 4mm, with a length of 6 meters.
- Outer Dimensions: 100mm x 50mm
- Inner Dimensions: (100 – 8) = 92mm, (50 – 8) = 42mm
- Outer Area: $0.1m \times 0.05m = 0.005 m^2$
- Inner Area: $0.092m \times 0.042m = 0.003864 m^2$
- Section Area: $0.005 – 0.003864 = 0.001136 m^2$
- Volume: $0.001136 m^2 \times 6m = 0.006816 m^3$
- Weight: $0.006816 m^3 \times 7850 kg/m^3 \approx 53.51 kg$
Example 2: Aluminum Tube (Imperial)
Consider an aluminum tube 4″ x 2″ x 0.125″ (1/8″), 10 feet long.
- Outer Area: $4 \times 2 = 8 sq in$
- Inner Dimensions: $(4 – 0.25) = 3.75″$, $(2 – 0.25) = 1.75″$
- Inner Area: $3.75 \times 1.75 = 6.5625 sq in$
- Wall Area: $8 – 6.5625 = 1.4375 sq in$
- Volume: $1.4375 sq in \times 120 inches (10ft) = 172.5 cu in$
- Weight: $172.5 \times 0.0975 lbs/cu in \approx 16.82 lbs$
How to Use This Calculator
Our tool simplifies the process of how to calculate weight of rectangular tube. Follow these steps:
- Select System: Choose between Metric (mm/kg) or Imperial (inch/lbs).
- Choose Material: Select standard materials like Steel or Aluminum. The density updates automatically. Use "Custom" for specific alloys.
- Enter Dimensions: Input the outer width, outer height, and wall thickness.
- Set Length & Quantity: Enter the length of the tube and how many pieces you need.
- Review Results: The calculator instantly provides the total weight, weight per meter/foot, and surface area.
Key Factors Affecting Tube Weight
When learning how to calculate weight of rectangular tube, consider these real-world factors that may cause deviations from theoretical calculations:
1. Corner Radius
Most rectangular tubes are not perfectly sharp at the corners; they have a radius. This removes a small amount of material compared to a theoretical square corner, making the actual tube slightly lighter than the calculated result.
2. Manufacturing Tolerances
Steel mills produce tubes within specific tolerance ranges (e.g., ASTM A500). Wall thickness can vary by +/- 10%, which directly impacts the final weight.
3. Material Density Variations
While steel is generally calculated at 7850 kg/m³, specific alloys may vary. Stainless steel is slightly heavier, while different grades of aluminum have varying densities.
4. Surface Coatings
Galvanizing, painting, or powder coating adds mass. While negligible for small pieces, heavy galvanization can add 3-5% to the weight of large structural members.
5. Weld Seams
Welded tubes may have an internal weld bead that adds a small amount of volume and weight compared to seamless tubes.
6. Cut Losses
If you are calculating weight for purchasing, remember that saw cuts remove material (kerf), but you generally pay for the full raw length before cutting.
Frequently Asked Questions (FAQ)
Does this calculator account for corner radius?
This calculator uses the standard geometric subtraction method (Outer Box – Inner Box). It provides a theoretical maximum weight. Actual weight may be 1-3% lighter due to rounded corners.
What is the density of mild steel?
The standard density used for mild steel is 7850 kg/m³ or approximately 0.2836 lbs/in³.
Can I calculate the weight of a square tube?
Yes. Simply enter the same value for both the "Outer Width" and "Outer Height" fields.
Why is my actual tube lighter than the calculated weight?
This is usually due to the corner radius (which removes material) or the wall thickness being on the lower end of the manufacturing tolerance.
How do I calculate weight for stainless steel?
Select "Stainless Steel" in the material dropdown. Stainless steel is slightly denser than mild steel, typically around 7900 kg/m³.
Is this calculator suitable for structural load planning?
While accurate, this tool provides theoretical weights. For critical structural engineering, always refer to the manufacturer's data sheets and apply appropriate safety factors.
What is the difference between RHS and SHS?
RHS stands for Rectangular Hollow Section, while SHS stands for Square Hollow Section. The calculation method for weight is identical for both.
How does wall thickness affect the cost?
Thicker walls increase the weight significantly. Since metals are often sold by weight (e.g., price per kg or lb), increasing thickness increases cost proportionally.
Related Tools and Resources
- Metal Weight Calculator – Calculate weight for plates, rounds, and angles.
- Steel Beam Load Calculator – Determine load capacities for structural beams.
- Aluminum Grade Guide – Compare properties of 6061, 5052, and 7075 aluminum.
- Welding Cost Estimator – Estimate labor and material costs for welding projects.
- Metric to Imperial Converter – Quick conversion for engineering units.
- Pipe vs Tube Differences – Learn the distinction between structural tube and piping.