Construction & Structural Engineering

Steel Weight Calculator

Calculate the exact weight of any steel section — rebar / TMT bar, round bar, flat bar, square bar, hollow pipe, angle iron, C-channel, plate/sheet, and I-beam / H-beam. Full step-by-step working, unit weight per metre, total weight in kg & tonnes, and optional cost estimate.

9 Section Types
Step-by-Step Working
kg/m Unit Weight Table
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Steel Weight Calculator — 9 Section Types

Select a section type, enter dimensions and length, get instant weight with complete step-by-step working

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Rebar / TMT Bar
Round deformed bar
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Round Bar
Solid circular bar
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Flat Bar
Width × thickness
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Square Bar
Solid square section
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Pipe / Hollow
Round hollow section
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Angle Iron
L-section / equal angle
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C-Channel
PFC / U-section
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Plate / Sheet
MS plate / GI sheet
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I-Beam / H-Beam
UC / UB section
🔩 Rebar / TMT Bar — Weight (kg/m) = d² ÷ 162.2  ·  Total = kg/m × Length × Qty
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Inner Diameter = OD − 2×t. For square hollow sections use flat bar method (perimeter × thickness × length × density).
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Cross-section area = H×t + 2×B×t − 2×t² (web + 2 flanges, deducting corner overlaps)
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Area = 2×(B×tf) + (H−2×tf)×tw. For standard ISMB/UC/UB sections, use the quick-select buttons for IS 808 dimensions.
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    Steel Weight Calculation — Complete Guide

    The formulas, density constants, and rules every engineer, fabricator, and site supervisor needs to know

    Fundamentals
    Why Steel Weight Matters in Construction

    Knowing the exact weight of steel is essential for structural design, procurement, transportation, and cost estimation. An underestimate leads to under-ordered material and project delays; an overestimate wastes money. Steel is universally priced by weight (₹/kg or ₹/tonne), so accurate weight calculation directly determines material cost.

    The universal formula is: Weight = Volume × Density. For steel, the standard density used in IS 800, BS 5950, and AISC is 7850 kg/m³ (7.85 g/cm³). This applies to mild steel, TMT rebar (Fe415/Fe500), structural steel sections, and most carbon steels. Stainless steel is slightly denser (7900–8000 kg/m³ depending on grade).

    Master formula — works for any steel shape:
    Weight (kg) = Cross-sectional Area (mm²) ÷ 1,000,000 × Length (m) × Density (kg/m³)

    For mild steel (7850 kg/m³) this simplifies to:
    Weight (kg) = Cross-sectional Area (mm²) × Length (m) × 0.00785
    Section-by-Section Formulas
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    Rebar / TMT Bar (Quick Formula)

    kg/m = d² ÷ 162.2 (d in mm). This shortcut is derived from π/4 × d² × 7850 ÷ 10⁶. For 12mm: 144÷162.2 = 0.888 kg/m. For 16mm: 256÷162.2 = 1.579 kg/m. Memorise this formula — it's used on every construction site in India.

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    Plate / Sheet (Quick Formula)

    kg = L(m) × W(m) × t(mm) × 7.85. A full 2.4×1.2m sheet in 6mm: 2.4×1.2×6×7.85 = 135.6 kg. In 10mm: 2.4×1.2×10×7.85 = 226 kg. This formula is used for estimating MS plate, chequered plate, and GI sheet orders.

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    Pipe / Hollow Section

    kg/m = π × (OD − t) × t × 7.85 × 10⁻³ (OD and t in mm). Or equivalently: kg/m = 0.02466 × t × (OD − t). For OD 60.3mm, t 3.6mm: 0.02466 × 3.6 × 56.7 = 5.03 kg/m.

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    Equal Angle Iron

    Area = t × (2a − t) where a = leg length, t = thickness. Example 75×75×6: Area = 6×(150−6) = 864 mm². Weight = 864×7850×10⁻⁶ = 6.78 kg/m. IS 808 tabulates exact values for standard angles.

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    I-Beam / H-Beam (ISMB)

    Area = 2×(B×tf) + (H−2×tf)×tw. This gives the net steel cross-section area excluding fillets. For ISMB 200 (H=200, B=100, tf=10, tw=6): Area = 2×(100×10)+(180×6) = 3080 mm². Weight = 3080×7850×10⁻⁶ = 24.2 kg/m (IS 808 tabulated: 25.4 kg/m including fillets).

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    C-Channel (ISMC)

    Area = H×t + 2×B×t − 2×t² (web + 2 flanges − corner double-counts). ISMC 100 (H=100, B=50, t=6): Area = 100×6 + 2×50×6 − 2×36 = 1128 mm². Weight = 1128×7850×10⁻⁶ = 8.85 kg/m.

    Standard Rebar / TMT Bar Weight Table

    Unit weight per metre for all standard IS 1786 bar diameters — ready reference for site engineers

    Formula: Weight (kg/m) = d² ÷ 162.2  ·  where d = nominal diameter in mm
    This is derived from: (π/4 × d² × 7850) ÷ 10⁶ = d² × 0.006165 ≈ d² / 162.2
    Dia (mm)kg / mkg / 6m barkg / 12m barBars per tonne (12m)IS 1786 Grade
    Rebar grades in India (IS 1786): Fe415 (415 MPa yield) — most common for residential RCC. Fe500 / Fe500D — higher strength, used for columns and foundations. Fe550 / Fe600 — high-strength seismic applications. The "D" suffix indicates improved ductility (elongation ≥ 14.5%). Always match rebar grade to structural engineer's specification.

    Steel Section Weight Formula Reference

    All 9 section types — formulas, cross-section area, and worked examples

    SectionArea Formulakg/m FormulaExampleResult
    Round Bar / Rebarπ/4 × d²d² / 162.2d=20mm, 6m1.234 kg/m → 7.4 kg
    Flat BarW × tW × t × 7.85×10⁻³50×6mm, 6m2.355 kg/m → 14.1 kg
    Square Bara²a² × 7.85×10⁻³25mm sq, 6m4.906 kg/m → 29.4 kg
    Pipe (CHS)π/4 × (OD²−ID²)0.02466×t×(OD−t)OD60, t4mm, 6m5.55 kg/m → 33.3 kg
    Equal Anglet × (2a − t)Area × 7.85×10⁻³75×75×6, 6m6.78 kg/m → 40.7 kg
    Unequal Anglet×(A+B−t)Area × 7.85×10⁻³100×75×8, 6m12.9 kg/m → 77.4 kg
    C-ChannelH×t + 2×B×t − 2×t²Area × 7.85×10⁻³100×50×6, 6m8.85 kg/m → 53.1 kg
    Plate / SheetL × W (per m² = t×7.85)L×W×t×7.85×10⁻³2.4×1.2×10mm226 kg total
    I-Beam / H-Beam2×B×tf + (H−2tf)×twArea × 7.85×10⁻³ISMB 200, 6m≈24.2 kg/m → 145 kg
    Unit conversions: 1 tonne = 1000 kg. Steel density = 7.85 g/cm³ = 7850 kg/m³ = 0.00785 kg/mm² per metre. To convert cm² to kg/m: multiply by 0.785.

    Steel Types, Grades & Their Applications

    From mild steel to high-strength alloys — knowing which grade to use and why it matters

    Steel is not a single material — it is a family of iron-carbon alloys with different proportions of carbon, manganese, silicon, and other alloying elements that dramatically change mechanical properties. The carbon content is the most important variable: low carbon (mild steel) <0.3% is soft and weldable; medium carbon 0.3–0.6% is stronger but less ductile; high carbon >0.6% is very hard but brittle.

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    TMT Rebar — Fe415/Fe500/Fe500D

    Thermo-Mechanically Treated bars. The outer surface is quenched to form a hard martensite rim while the core remains soft and ductile. This gives high yield strength with good elongation. Fe500D is mandatory in seismic zones III, IV, and V in India per IS 13920.

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    Structural Steel — IS 2062 E250/E350

    Mild steel plates, angles, channels, and beams are specified as IS 2062 grade. E250 (formerly Fe 410-W) has 250 MPa yield strength. E350 has 350 MPa. E250 is used for general fabrication; E350 for high-stressed members, bridges, and crane girders.

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    Stainless Steel — 304/316/430

    Grade 304 (18% Cr, 8% Ni) is the most common — kitchens, cladding, handrails. Grade 316 adds molybdenum for superior corrosion resistance in marine and chemical environments. Grade 430 is ferritic (no nickel) — cheaper but lower corrosion resistance. Density: 7900–8000 kg/m³.

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    MS Pipe — IS 1239 / IS 3589

    ERW (Electric Resistance Welded) pipes for water, gas, and structural use. IS 1239 covers light, medium, and heavy class pipes from 6mm to 150mm NB. IS 3589 covers larger diameter pipes. Structural hollow sections (SHS/RHS) are specified to IS 4923.

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    Angle & Channel — IS 808

    IS 808 tabulates dimensions and weights for all standard ISMC (channels) and ISA (angles) sections. ISMC 100 weighs 9.56 kg/m; ISMC 200 weighs 22.1 kg/m. ISA 65×65×6 weighs 5.8 kg/m; ISA 100×100×10 weighs 15.1 kg/m. Always cross-check calculator results against IS 808 tables for standard sections.

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    High-Strength Steel — Fe550/Fe690

    Used in bridges, pre-stressed structures, and offshore platforms where reduced section sizes are needed to save weight. Fe550 rebar has 550 MPa yield strength. High-strength low-alloy (HSLA) steels like Corten/weathering steel offer atmospheric corrosion resistance without painting.

    Frequently Asked Questions — Steel Weight

    Answers to the most common steel weight and calculation questions from engineers, fabricators, and builders

    What is the formula for calculating steel weight?
    The universal formula is: Weight (kg) = Volume (m³) × Density (7850 kg/m³). Volume = Cross-sectional Area (m²) × Length (m). For practical use with dimensions in mm: Weight (kg) = Area (mm²) × Length (m) × 0.00785. For round bars and rebar specifically, the shortcut is: Weight (kg/m) = d² ÷ 162.2, where d is diameter in mm. This is valid for all mild steel and TMT rebar.
    What is the unit weight of steel in kg/m³?
    The standard unit weight (mass density) of mild steel, structural steel, and TMT rebar is 7850 kg/m³ (7.85 g/cm³ or 0.00785 kg/mm² per metre). This value is used in IS 800, BS 5950, Eurocode 3, and AISC specifications. Stainless steel grades 304 and 316 are slightly denser at 7900 and 7950 kg/m³ respectively. Cast iron is approximately 7200 kg/m³ (lighter than steel). Aluminium is only 2700 kg/m³ — about one-third the weight of steel for the same volume.
    How do I calculate rebar weight for a slab?
    Calculate the total length of rebar needed first: count the number of bars in each direction (slab length/spacing + 1) × bar length, for both main and distribution steel. Then use: Weight = (total length in metres) × (d² ÷ 162.2). Example: 6m×4m slab, 12mm @ 150mm c/c both ways. Bars in X = (4000/150+1) = 27 bars × 6m = 162m. Bars in Y = (6000/150+1) = 41 bars × 4m = 164m. Total = 326m. Weight = 326 × (144/162.2) = 326 × 0.888 = 289 kg.
    How do you calculate the weight of an MS plate or sheet?
    Use: Weight (kg) = Length (m) × Width (m) × Thickness (mm) × 7.85. This is the quick formula derived from L × W × (t/1000) × 7850. Examples: A 2.4m × 1.2m sheet in 6mm = 2.4 × 1.2 × 6 × 7.85 = 135.6 kg. Same sheet in 10mm = 226 kg. A 3m × 1.5m plate in 20mm = 3 × 1.5 × 20 × 7.85 = 706.5 kg. Standard IS 2062 plate comes in 2.5m × 1.25m or 2.44m × 1.22m (8×4 feet) sheets.
    What is the weight of a 12mm rebar per metre and per 12m bar?
    Using the formula d²/162.2: 12mm rebar = 144/162.2 = 0.888 kg/m. Per 12m bar: 0.888 × 12 = 10.66 kg per bar. A full tonne bundle (1000 kg) contains 1000/10.66 ≈ 94 bars of 12m. In terms of total length: 1000 ÷ 0.888 ≈ 1126 metres per tonne of 12mm rebar. This is a commonly needed figure when ordering from steel stockists and TMT manufacturers.
    How is the weight of a steel pipe calculated?
    Pipe weight = volume of steel in the tube wall × density. Area of annular cross-section = π/4 × (OD² − ID²), where ID = OD − 2×wall thickness. Quick formula: kg/m = 0.02466 × t × (OD − t), where OD and t are in mm. Example: 114.3mm OD, 6mm wall: 0.02466 × 6 × 108.3 = 16.01 kg/m. For a 6m length: 96.1 kg. This formula is used for ERW, seamless, and hollow structural section (SHS/RHS) pipes.
    What is the difference between Fe415, Fe500, and Fe500D rebar?
    These are TMT rebar grades per IS 1786. The number indicates the minimum yield strength in MPa. Fe415 has 415 MPa yield strength and is the traditional grade used for residential work. Fe500 has 500 MPa yield — stronger, allowing smaller diameter bars for the same structural capacity. Fe500D adds the 'D' for improved ductility: minimum 14.5% elongation and tighter limits on the yield-to-ultimate strength ratio, making it mandatory in seismic zone III, IV, and V structures per IS 13920. The weight per metre is identical for the same diameter across all grades — only the mechanical properties differ.
    How accurate is this steel weight calculator?
    This calculator uses the standard density of 7850 kg/m³ for mild steel/TMT rebar as specified in IS 800 and IS 1786. For round bars and rebar, it uses the exact formula π/4 × d² × 7850 × 10⁻⁶ (equivalent to d²/162.2 rounded to 4 significant figures). Results typically match IS 808 tabulated values for standard sections within 1–2% (the small discrepancy is due to fillets and root radii in rolled sections that this calculator does not include). For procurement purposes, always add a standard wastage allowance of 3–5%.
    How many kg of steel are in one tonne, and how is steel priced?
    One metric tonne = 1000 kg exactly. Steel is typically priced per kilogram (₹/kg) for rebar and structural sections. In India (2024), TMT rebar prices typically range from ₹55–75/kg depending on grade and market conditions; MS structural sections ₹60–80/kg; stainless steel 304 ₹180–250/kg; plates and sheets vary by thickness. Prices fluctuate with global iron ore, coking coal, and scrap metal prices. Always get current market rates from your steel stockist — the cost estimate feature in this calculator uses your entered price per kg for an indicative figure only.