Round Bar (Rod)
Square Bar
Rectangular / Flat Bar
Hexagonal Bar
Select the cross-sectional shape.
Length of the bar in millimeters.
Length must be greater than 0.
Outer diameter in mm.
Value must be greater than 0.
Thickness in mm.
Value must be greater than 0.
Number of bars.
Quantity must be at least 1.
Enter material cost to estimate total value.
Total Weight
15.41 kg
Unit Weight
15.41 kg
Total Volume
1963.5 cm³
Estimated Cost
–
Formula Used: Weight = Volume × Density.
For a Round Bar: Volume = π × (Diameter/2)² × Length.
Calculated as: π × (25mm)² × 1000mm × 7850 kg/m³.
Weight Breakdown & Comparison
Figure 1: Comparison of calculated weight against other common materials for the same dimensions.
Specification Summary
Parameter
Value
Material
Steel
Shape
Round
Dimensions
Dia: 50mm, Len: 1000mm
Quantity
1
Comprehensive Guide to Calculate Weight of Bar
What is Calculate Weight of Bar?
To calculate weight of bar is a fundamental process in engineering, construction, and logistics that involves determining the mass of a structural element based on its dimensions and material density. Whether you are ordering steel reinforcement for concrete, estimating shipping costs for aluminum profiles, or designing a brass component, knowing the exact weight is crucial for safety and budgeting.
This calculation is essential for fabrication shops, civil engineers, and procurement managers. A common misconception is that weight can be estimated solely by visual size; however, different materials vary significantly in density. For example, a gold bar weighs nearly three times as much as a steel bar of the exact same size. Accurate calculation prevents structural failures and cost overruns.
Calculate Weight of Bar Formula and Mathematical Explanation
The core mathematics to calculate weight of bar relies on the relationship between volume and density. The universal formula used is:
Weight (W) = Volume (V) × Density (ρ)
To find the weight, you must first calculate the volume of the bar, which depends on its cross-sectional shape.
Formulas by Shape
Round Bar: V = π × r² × L (where r is radius, L is length)
Square Bar: V = a² × L (where a is side width)
Rectangular (Flat) Bar: V = Width × Thickness × Length
Hexagonal Bar: V = (3√3 / 2) × a² × L (where a is side length)
Variable
Meaning
Unit (Metric)
Typical Range
W
Total Weight
kg
0.1 – 5000+
V
Volume
m³ or cm³
Varies
ρ (Rho)
Material Density
kg/m³
2700 (Al) – 7850 (Steel)
L
Length of Bar
mm or m
100mm – 12m
Practical Examples (Real-World Use Cases)
Example 1: Steel Reinforcement Bar (Rebar)
A construction site needs to calculate weight of bar for 50 pieces of 16mm diameter steel rebar, each 6 meters long.
Material: Steel (Density ≈ 7850 kg/m³)
Radius (r): 8mm = 0.008m
Length (L): 6m
Volume per bar: π × (0.008)² × 6 ≈ 0.001206 m³
Weight per bar: 0.001206 × 7850 ≈ 9.47 kg
Total Weight: 9.47 kg × 50 ≈ 473.5 kg
Financial Impact: At $1.20 per kg, this order costs approx $568.
Example 2: Aluminum Flat Bar for Fabrication
A workshop needs to check the shipping weight of an aluminum flat bar measuring 50mm wide, 10mm thick, and 3 meters long.
Material: Aluminum (Density ≈ 2700 kg/m³)
Volume: 0.05m × 0.01m × 3m = 0.0015 m³
Weight: 0.0015 × 2700 = 4.05 kg
How to Use This Calculator
Select Material: Choose from common metals like Steel, Aluminum, or Brass. If your material isn't listed, select "Custom Density" and enter the value in kg/m³.
Choose Shape: Select the profile of your bar (Round, Square, Flat, or Hex).
Enter Dimensions: Input the length and cross-sectional dimensions (diameter, width, thickness) in millimeters (mm).
Set Quantity: Enter the number of bars you need to calculate.
Input Cost (Optional): If you know the price per kg, enter it to see an estimated total cost.
Review Results: The tool will instantly display the unit weight, total weight, and visual comparisons.
Key Factors That Affect Weight Results
When you calculate weight of bar, several real-world factors influence the final accuracy:
Specific Alloy Density: "Steel" is a generic term. Stainless steel (304) is slightly denser (7900 kg/m³) than mild steel (7850 kg/m³). Always check the specific alloy grade.
Dimensional Tolerances: Manufacturing standards allow small deviations in diameter or thickness. A "50mm" bar might actually be 50.5mm, increasing weight by ~2%.
Corner Radius: Square and flat bars often have rounded corners (radius) rather than sharp 90-degree edges, slightly reducing the actual volume and weight.
Surface Coating: Galvanizing or painting adds a small amount of mass, usually negligible for heavy structural steel but relevant for precision parts.
Temperature: Metals expand with heat. While mass remains constant, volume changes. Standard densities are usually quoted at 20°C (68°F).
Hollow Sections: This calculator assumes solid bars. If you are calculating pipe or tube, you must subtract the volume of the inner void.
Frequently Asked Questions (FAQ)
Why does the calculator use kg/m³ for density?
Kilograms per cubic meter is the standard SI unit for density in engineering. It provides a consistent baseline for calculations across different scales.
How accurate is the result when I calculate weight of bar?
The calculation is mathematically exact based on the inputs. However, real-world weights may vary by 1-3% due to manufacturing tolerances and specific alloy compositions.
Can I calculate weight for plastic or wood bars?
Yes. Select "Custom Density" and enter the density of your specific plastic (e.g., Nylon approx 1150 kg/m³) or wood.
What is the difference between weight and mass in this context?
Technically, mass is the amount of matter (kg), and weight is the force of gravity acting on it (Newtons). However, in industry and commerce, "weight" is colloquially used to refer to mass in kg or lbs.
How do I convert millimeters to meters for manual calculation?
Divide the millimeter value by 1000. For example, 50mm becomes 0.05m. This is crucial before multiplying by density in kg/m³.
Does length affect density?
No. Density is an intrinsic property of the material. Length only affects the total volume and thus the total weight.
Is the price estimation legally binding?
No. The price output is a rough estimation based on your input. Metal prices fluctuate daily based on global markets.
Can I calculate weight of bar for hexagonal profiles?
Yes, select "Hexagonal Bar" in the shape dropdown. The calculator uses the distance across flats (the standard sizing method for hex keys and bars) to determine the area.
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