About Steel Weight Calculation
This steel weight calculator determines the theoretical mass of metal profiles based on cross-sectional dimensions, length, and material density. It supports round bars and rebar, round pipes, I-beams, channels, angles, plates, T-sections, and rectangular or square hollow sections.
For I-beams and channels, the calculator also provides calculations based on the tabulated mass of standard European IPE, HEA, HEB, UPN, and UPE profiles. The results help determine the mass per metre, the mass of an individual piece, and the total mass of multiple identical pieces when purchasing steel, manufacturing metal components, or planning transportation.
Guidelines and Recommendations
General Principle of Mass Calculation
Calculation from geometry. First, the cross-sectional area of the metal, S, is determined in mm2 using the section dimensions in millimetres. The area is converted to m2 and multiplied by the material density ρ in kg/m3. The resulting value is the mass per linear metre in kg/m.
M1 = S × ρ / 106
The factor 106 converts the cross-sectional area from mm2 to m2. The mass per metre is then multiplied by length L in metres, and the mass of one piece is multiplied by quantity N.
Mpiece = M1 × L
Mtotal = Mpiece × N
Steel density. The default value is 7850 kg/m3, a commonly used design density for structural carbon steel. When the density changes, the calculated mass changes proportionally: a 2% increase in density produces a 2% increase in mass if the geometry remains unchanged.
For example, a round steel bar with a diameter of 16 mm and a density of 7850 kg/m3 has a theoretical mass of approximately 1.578 kg/m. For a length of 2 m, the mass of one bar is about 3.157 kg.
Round Bars and Rebar
Circular cross-sectional area. The area is calculated from diameter d in millimetres. The mathematical constant π ≈ 3.141592653589793 is used without preliminary rounding to 3.14.
S = π × d2 / 4
For reinforcing steel bars, the area is calculated using the nominal diameter of a circular section. No separate correction factors are applied for the ribs of deformed rebar.
Round Pipes
Annular cross-sectional area. The area of the internal opening is subtracted from the area of the outer circle. The internal diameter equals the outside diameter d minus twice the wall thickness t.
S = π × t × (d - t)
Dimensions d and t are expressed in millimetres. For an internal opening to exist, the wall thickness must be less than half the outside diameter: 2t < d. The formula accounts for the hollow interior without additional correction factors.
I-Beams, Channels, and T-Sections with Custom Dimensions
Composite cross-section. The area is calculated by adding the areas of the rectangular parts of the profile. Areas shared by the web and flanges are counted only once. Fillet radii and flange slopes are not modelled in these formulas.
I-beam. The area of two flanges of width b and thickness h1 is added to the area of the central web of thickness t. The web height between the flanges equals h − 2h1.
S = (h - 2h1) × t + 2 × b × h1
Channel. The area of the web, with thickness s and height h − 2t, is added to the area of two flanges of width b and thickness t.
S = (h - 2t) × s + 2 × b × t
T-section. The area of one flange of width b and thickness h1 is added to the area of the web of thickness t located below that flange.
S = b × h1 + (h - h1) × t
For I-beams and channels, the combined thickness of the two flanges must be less than the total section height. For T-sections, the flange thickness must be less than the overall height. The web thickness must not exceed the flange width. If these geometric conditions are not satisfied, the mass is not calculated.
Angles, Plates, and Hollow Sections
Angle section. The area equals the sum of the areas of two perpendicular legs minus their overlapping square region. The same formula applies to equal-leg and unequal-leg angles.
S = t × (a + b - t)
Here, a and b are the leg dimensions, and t is their common thickness. The thickness must be smaller than each leg dimension. Internal and external corner radii are not included in the calculation.
Plate or flat bar. The rectangular cross-sectional area is calculated by multiplying width b by thickness t.
S = b × t
Rectangular hollow section. The area is calculated as the difference between the areas of the outer rectangle and the internal opening. For height h, width b, and uniform wall thickness t, the formula is:
S = 2 × t × (h + b - 2t)
The wall thickness must be less than half the smaller outside dimension: 2t < min(h, b). The calculation assumes square corners without corner radii. No additional reduction factor is applied for the corners of the hollow section.
Standard European Steel Profiles
Tabulated mass. For standard I-beams of the IPE, HEA, and HEB series and channels of the UPN and UPE series, the mass per linear metre is taken directly from the built-in table of profile sizes. The cross-sectional area is not recalculated: the selected tabulated value in kg/m is used as the starting point for calculating mass from length.
For example, the table specifies 22.4 kg/m for IPE 200 and 25.3 kg/m for UPN 200. For an IPE 200 beam with a length of 2.5 m, the mass of one piece is 22.4 × 2.5 = 56 kg, while three identical pieces have a total mass of 168 kg.
Assumed density. The tabulated masses of standard profiles correspond to a nominal steel density of 7850 kg/m3. No separate density adjustment is applied to these values. Unlike calculations based on simplified rectangular cross-sections, the tabulated mass accounts for the characteristics of the nominal geometry of rolled steel profiles.
Selection of the calculation method. For a standard profile, the final result is determined from its tabulated mass. For a profile with custom dimensions, the geometric cross-sectional area and specified density are used. The results of these two methods are not averaged, and no percentage correction factors are added.
Precision and Rounding
Intermediate calculations. The cross-sectional area and mass per metre are calculated without intermediate rounding. Rounding is applied when displaying the results. For masses of 10 kg or more, up to two decimal places are shown; from 0.01 kg to less than 10 kg, three decimal places are used; and for smaller values, four decimal places are used. Values below 0.0001 kg are displayed in scientific notation.
Total mass. The total mass is calculated by multiplying the rounded mass of one piece by the integer quantity, after which the result is also rounded for display. Therefore, the displayed total mass is consistent with the displayed mass of an individual piece within the precision of the output.
Related European Standards
I-beams and channels. EN 10365 "Hot Rolled Steel Channels, I and H Sections — Dimensions and Masses" specifies the nominal characteristics of rolled steel profiles, including the IPE, HE, UPN, and UPE series. Dimensional and shape tolerances are also covered by EN 10034 "Structural Steel I and H Sections — Tolerances on Shape and Dimensions" and EN 10279 "Hot Rolled Steel Channels — Tolerances on Shape, Dimensions and Mass".
Angle sections. EN 10056-1 "Structural Steel Equal and Unequal Leg Angles — Part 1: Dimensions" specifies the nominal dimensions and characteristics of hot-rolled angle sections. Shape and dimensional tolerances are defined in EN 10056-2 "Part 2: Tolerances on Shape and Dimensions".
Structural hollow sections. EN 10219-2 "Cold Formed Welded Structural Hollow Sections of Non-Alloy and Fine Grain Steels — Part 2: Tolerances, Dimensions and Sectional Properties" and EN 10210-2 "Hot Finished Structural Hollow Sections of Non-Alloy and Fine Grain Steels — Part 2: Tolerances, Dimensions and Sectional Properties" provide reference data for comparing calculated pipe and hollow-section masses with standard steel product characteristics.
Reinforcing steel. EN 10080 "Steel for the Reinforcement of Concrete — Weldable Reinforcing Steel — General" establishes general requirements for reinforcing steel products. When comparing mass calculated from nominal diameter with supplier data, the characteristics of the specific reinforcing steel product should be considered.
Nominal values from standards and catalogues may differ from the actual mass of a product within manufacturing tolerances. When estimating the mass of a specific batch of steel products, the mass per metre from the manufacturer's specification and the actual lengths of the supplied pieces are commonly used.
FAQs
Why Does the Mass of a Standard I-Beam Differ from the Result Calculated from Its Dimensions?
In standard steel profile tables, the mass per metre is specified using a tabulated value that accounts for the nominal shape of the rolled section. When calculating an I-beam from its dimensions, the web and flanges are represented as rectangles without fillets and transition regions. As a result, the values may differ even when the main dimensions are identical.
What Steel Density Should Be Used for Weight Calculation?
For ordinary structural steel, a commonly used design density is 7850 kg/m3. If the density of a particular material is known, it can be used for calculations based on geometry. The calculated mass changes in direct proportion to the ratio of the new density to the original value.
Why Can Rebar Have a Different Mass Than a Smooth Round Bar of the Same Diameter?
The calculator determines theoretical mass from the circular cross-sectional area and nominal diameter. Deformed reinforcing bars have ribs and indentations, while their nominal mass is defined by the characteristics of the specific product. For standard rebar, the tabulated mass per metre can provide a more accurate reference value.
How Is the Total Weight of Multiple Identical Steel Pieces Calculated?
First, the mass per metre of the cross-section is determined, followed by the mass of one piece of the specified length. This value is then multiplied by the number of identical pieces. All pieces in the batch are assumed to have the same dimensions, length, and material density.
Which Method Is More Accurate for an I-Beam or Channel: Standard Profile Data or Custom Dimensions?
If the steel section corresponds to a standard IPE, HEA, HEB, UPN, or UPE series, the tabulated mass of the selected profile size is preferable. For a non-standard section, mass is calculated from the specified dimensions and steel density. The difference between the methods mainly results from how the nominal geometry of the rolled profile is accounted for.