Accurately calculate steel weight per meter for various shapes and sizes
Steel Weight Estimator
Round Bar
Square Bar
Flat Bar / Plate
Pipe / Tube (Hollow)
Select the cross-sectional shape of the steel.
Enter the diameter in millimeters.
Please enter a valid positive number.
Enter the side width in millimeters.
Please enter a valid positive number.
Enter the width in millimeters.
Enter the thickness in millimeters.
Thickness of the pipe wall.
Wall thickness cannot exceed radius.
Standard lengths are often 6m or 12m.
Enter current market price per kg for cost estimation.
Weight Per Meter
2.47 kg/m
Based on standard steel density of 7850 kg/m³
Total Weight (All Pieces)
14.82 kg
Total Volume
0.0019 m³
Estimated Total Cost
$22.23
Specification Breakdown
Parameter
Value
*Calculations assume nominal dimensions and standard density.
Material Density Comparison (Weight per Meter)
Comparing your selected shape against Aluminum and Stainless Steel.
How to Calculate Steel Weight Per Meter: The Complete Guide
Understanding how to calculate steel weight per meter is a fundamental skill for engineers, fabricators, quantity surveyors, and construction professionals. Whether you are estimating transport costs, checking structural loads, or purchasing raw materials, knowing the theoretical weight of steel sections is critical for accurate budgeting and safety planning.
This guide provides a deep dive into the formulas, methodologies, and practical examples used to determine the weight of various steel profiles. By mastering these calculations, you can avoid costly ordering errors and ensure your projects remain within structural limits.
What is Steel Weight Calculation?
Steel weight calculation involves determining the mass of a steel section based on its volume and density. Since steel is sold by weight (typically per kilogram or ton), converting linear dimensions (length, width, thickness) into weight is the primary method for pricing and logistics.
The industry standard density for mild steel is approximately 7850 kg/m³ (kilograms per cubic meter). While different alloys like stainless steel may vary slightly, this figure is the baseline for most construction steel calculations.
Why is this important?
If you order 1000 meters of 20mm steel bar, you aren't just buying length; you are buying approximately 2.47 tons of material. Miscalculating this weight can lead to overloaded trucks, crane failures, or significant budget overruns.
Steel Weight Formula and Mathematical Explanation
The core formula for how to calculate steel weight per meter is derived from the relationship between mass, density, and volume. The general equation is:
Weight (kg) = Volume (m³) × Density (kg/m³)
To find the weight per meter, we calculate the volume of a one-meter length. This simplifies to:
Weight/m = Cross-Sectional Area (m²) × 7850
Variable Definitions
Variable
Meaning
Unit
Typical Value
A
Cross-Sectional Area
Square Meters (m²)
Depends on shape
L
Length
Meters (m)
6m, 12m
ρ (Rho)
Density
kg/m³
7850 (Mild Steel)
Formulas by Shape
Round Bar: $Weight/m = \frac{\pi \times d^2}{4000000} \times 7850$ (where d is in mm)
Square Bar: $Weight/m = \frac{side^2}{1000000} \times 7850$
Flat Bar: $Weight/m = \frac{width \times thickness}{1000000} \times 7850$
Scenario: A site engineer needs to order 500 lengths of 16mm diameter rebar, each 6 meters long. He needs to know the total weight to book a delivery truck.
Result: At a steel price of $1.50/kg, the material cost is approximately $353.25.
How to Use This Steel Weight Calculator
Our tool simplifies the complex math into a few clicks. Follow these steps to get an instant estimation:
Select Shape: Choose between Round, Square, Flat, or Pipe from the dropdown menu.
Enter Dimensions: Input the required dimensions in millimeters (mm). For pipes, ensure the wall thickness is less than half the diameter.
Set Length & Quantity: Input the length in meters and the number of pieces required.
Review Results: The calculator instantly updates the "Weight Per Meter" and "Total Weight".
Cost Estimation: Optionally, enter a price per kg to see the estimated total cost of the material.
Key Factors That Affect Steel Weight Results
While the theoretical formula is precise, real-world weights can vary due to several factors:
Rolling Tolerances: Steel mills produce steel within specific tolerance ranges (e.g., +/- 2.5%). A bar sold as 20mm might actually be 20.2mm, increasing the weight slightly.
Material Density: While 7850 kg/m³ is standard for mild steel, Stainless Steel (Grade 304/316) is denser, typically around 7930 kg/m³.
Galvanization: Hot-dip galvanizing adds a layer of zinc, which increases the weight by approximately 3-5% depending on the surface area.
Corner Radius: Square and rectangular hollow sections often have rounded corners, which slightly reduces the actual steel volume compared to a perfect geometric square.
Rust and Corrosion: Heavily rusted steel may have lost mass, while surface scale can add negligible weight.
Alloy Composition: High-carbon steels or specific tool steels may have densities ranging from 7750 to 8050 kg/m³.
Frequently Asked Questions (FAQ)
1. Is the calculated weight exact?
No, it is a "theoretical weight." Actual weight varies due to manufacturing tolerances (rolling margins) which can be +/- 2% to 5%.
2. How do I calculate steel weight in lbs/ft?
To convert kg/m to lbs/ft, multiply the result by 0.6719. For example, 10 kg/m is approximately 6.72 lbs/ft.
3. Does this calculator work for Stainless Steel?
This calculator uses the density of mild steel (7850 kg/m³). For stainless steel, add approximately 1% to the final weight.
4. What is the density of steel?
The standard engineering density for Carbon Steel is 7850 kg/m³ or 7.85 g/cm³.
5. How do I calculate the weight of a steel pipe?
Subtract the volume of the inner void from the total cylinder volume. Formula: Weight = π × (OuterRadius² – InnerRadius²) × Length × Density.
6. Why is steel sold by weight and not length?
Weight is a more constant measure of material quantity than volume or length, which can fluctuate with temperature and shape complexity. It also correlates directly to shipping costs.
7. How do I calculate the weight of a steel beam (I-Beam)?
I-Beams have complex cross-sections. It is best to use standard tables provided by manufacturers or specialized beam calculators rather than simple geometric formulas.
8. Does painting affect the weight?
Paint adds negligible weight for general structural purposes, usually ignored in standard tonnage calculations unless precision aerospace engineering is involved.