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| Diameter (mm) | Weight per Metre (kg/m) | Weight per Foot (kg/ft) | Weight per 12m Bar (kg) |
|---|---|---|---|
| 6 mm | 0.222 | 0.068 | 2.66 |
| 8 mm | 0.395 | 0.120 | 4.74 |
| 10 mm | 0.617 | 0.188 | 7.40 |
| 12 mm | 0.889 | 0.271 | 10.67 |
| 16 mm | 1.580 | 0.482 | 18.96 |
| 20 mm | 2.469 | 0.753 | 29.63 |
| 25 mm | 3.858 | 1.176 | 46.30 |
| 28 mm | 4.834 | 1.473 | 58.01 |
| 32 mm | 6.316 | 1.925 | 75.79 |
| 36 mm | 7.990 | 2.435 | 95.88 |
| 40 mm | 9.864 | 3.007 | 118.37 |
| Thickness (mm) | Weight per m² (kg) | 2500×1250 mm Plate (kg) | 2000×1000 mm Plate (kg) |
|---|---|---|---|
| 3 mm | 23.55 | 73.6 | 47.1 |
| 5 mm | 39.25 | 122.7 | 78.5 |
| 6 mm | 47.10 | 147.2 | 94.2 |
| 8 mm | 62.80 | 196.3 | 125.6 |
| 10 mm | 78.50 | 245.3 | 157.0 |
| 12 mm | 94.20 | 294.4 | 188.4 |
| 16 mm | 125.60 | 392.5 | 251.2 |
| 20 mm | 157.00 | 490.6 | 314.0 |
| 25 mm | 196.25 | 613.3 | 392.5 |
| 32 mm | 251.20 | 785.0 | 502.4 |
Steel weight calculation is essential for construction estimation, logistics planning, and material procurement across India. The weight of any steel section depends on three factors: the cross-sectional area, the length, and the density of the material (7,850 kg/m³ for mild steel).
The most commonly used formula in steel construction is d² ÷ 162.2, where d is the bar diameter in mm. This gives weight in kg per metre. For example, a 16mm TMT bar: 16² ÷ 162.2 = 1.580 kg/m. A standard 12-metre bar weighs 18.96 kg. This formula is derived from the circular cross-section area (πd²/4) multiplied by the density of steel.
For flat products, use: Weight (kg) = L × W × T × 7.85 ÷ 1,000,000 (all dimensions in mm). A quicker method: Thickness (mm) × 7.85 = weight per square metre. So a 10mm plate weighs 78.5 kg/m².
For hollow round sections: Weight (kg/m) = (OD − WT) × WT × 0.02466, where OD is outer diameter and WT is wall thickness, both in mm.
Accurate steel weight calculation is fundamental to every stage of the construction and manufacturing supply chain. From initial project estimation to final invoice verification, knowing the exact weight of steel sections determines material costs, transport logistics, crane capacities, and structural load calculations. This comprehensive guide covers every formula, material grade, and section type used in modern steel construction.
Steel is purchased by weight — typically per kilogram or per metric tonne. Even a 2% error in weight estimation on a 500-tonne project translates to 10 tonnes of material, which at current market rates can represent a significant financial difference. Accurate weight calculations are critical for:
The d²/162.2 formula is the most widely used steel weight formula globally. It calculates the weight per metre of any round steel bar — including TMT rebar, bright bar, and round sections. The formula is derived as follows:
Cross-section area = π/4 × d² mm²
Volume per metre = π/4 × d² × 1000 mm³
Weight per metre = Volume × Density = π/4 × d² × 1000 × 7.85 × 10&sup6; kg
Simplifies to: d² ÷ 162.2 kg/m
The constant 162.2 comes from: 4 × 10&sup6; ÷ (π × 1000 × 7850) = 162.19. In practice, 162 is sometimes used as a rough approximation, but 162.2 gives results accurate to <0.1%. Common examples: 8mm TMT = 0.395 kg/m, 12mm = 0.889 kg/m, 16mm = 1.580 kg/m, 20mm = 2.469 kg/m, 25mm = 3.858 kg/m, 32mm = 6.316 kg/m.
Flat products — MS plates, HR sheets, chequered plates, and galvanised sheets — use the rectangular volume formula. With all dimensions in millimetres: Weight (kg) = L × W × T × 7.85 ÷ 1,000,000. The shortcut for quick estimation is: Thickness (mm) × 7.85 = weight per m². For example, a 10mm plate weighs 78.5 kg/m². A standard 2500 × 1250 mm plate at 10mm thickness weighs 78.5 × 3.125 = 245.3 kg.
For round pipes and tubes: Weight (kg/m) = (OD − WT) × WT × 0.02466, where OD is outer diameter and WT is wall thickness in mm. The constant 0.02466 = π × 7850 ÷ 10&sup6;. For square and rectangular hollow sections (SHS/RHS), the formula adapts to: Weight (kg/m) = (Perimeter − 4 × WT) × WT × 0.00785.
Steel angles use: Weight (kg/m) = (A + B − T) × T × 0.00785, where A and B are the leg lengths and T is the thickness, all in mm. For equal angles (e.g., 50 × 50 × 5mm), A = B = 50 and T = 5, giving (50 + 50 − 5) × 5 × 0.00785 = 3.73 kg/m.
Channel weight is best looked up from standard IS tables (IS 808) as the formula depends on exact fillet radii and web/flange dimensions. As an approximation: Weight ≈ (2 × Flange + Web − 2T) × T × 0.00785. Common sizes: ISMC 75 = 6.8 kg/m, ISMC 100 = 9.56 kg/m, ISMC 150 = 16.4 kg/m, ISMC 200 = 22.2 kg/m.
Like channels, I-beam weights are standardised per IS 808 and should be referenced from tables. Approximate formula: Weight ≈ (2 × B × tf + (H − 2tf) × tw) × 0.00785, where B = flange width, H = overall depth, tf = flange thickness, tw = web thickness. Common sizes: ISMB 100 = 11.5 kg/m, ISMB 150 = 14.9 kg/m, ISMB 200 = 25.4 kg/m, ISMB 300 = 44.2 kg/m.
Not all steel is the same density. While mild steel (MS) and carbon steel share a density of 7,850 kg/m³, other materials differ significantly:
To convert any mild steel weight to another material, multiply by the density factor. For example, if a round bar weighs 3.858 kg/m in MS, the same bar in aluminium weighs 3.858 × 0.344 = 1.327 kg/m.
TMT (Thermo-Mechanically Treated) bars come in several grades defined by IS 1786. The grade number indicates the minimum yield strength in MPa. Common grades include:
Importantly, the grade does not affect weight. All TMT grades use the same base steel density of 7,850 kg/m³. A 12mm Fe500 bar weighs exactly the same as a 12mm Fe550D bar — 0.889 kg/m. The grade only affects mechanical properties (yield strength, elongation, UTS) and the cost per kg.
All calculator results show theoretical weight based on nominal dimensions and standard density. Actual weight may differ by ±2–5% due to:
For commercial transactions, IS 1786 specifies that TMT bars should have a mass tolerance of ±5% for individual bars (diameter ≤10mm) and ±3% (diameter >10mm). For invoicing purposes, theoretical weight is typically accepted unless the buyer and seller agree on actual (weigh-bridge) weight.
Different steel sections serve different structural and construction purposes:
For preliminary estimation before detailed design, engineers use thumb rules to estimate reinforcement steel requirements:
These are rough estimates for initial budgeting. Actual quantities must be derived from structural drawings and the Bar Bending Schedule (BBS) prepared by the structural engineer.
Use the appropriate formula for the section type. For round bars/TMT: d² ÷ 162.2 = kg/m. For plates: L × W × T × 7.85 ÷ 1,000,000. For pipes: (OD − WT) × WT × 0.02466 = kg/m. All formulas assume mild steel density of 7,850 kg/m³.
The d²/162 formula (precisely d²/162.2) calculates TMT bar or round bar weight per metre. Square the diameter in mm, divide by 162.2, and you get kg/m. Example: 12mm bar = 144 ÷ 162.2 = 0.889 kg/m. The constant 162.2 is derived from 4 × 10&sup6; ÷ (π × 1000 × 7850).
A 12mm TMT bar weighs 0.889 kg per metre. A standard 12-metre bar weighs approximately 10.67 kg. This applies to all grades (Fe500, Fe500D, Fe550D) as the grade affects strength, not weight.
Mild steel density is 7,850 kg/m³ (7.85 g/cm³). Stainless steel SS304 is 8,000 kg/m³ and SS316 is 8,027 kg/m³. Our calculator adjusts automatically when you select a different grade.
Multiply Length × Width × Thickness (all in mm), then multiply by 7.85 and divide by 1,000,000. Quick shortcut: thickness in mm × 7.85 gives you weight per square metre in kg.
Theoretical weight is calculated from nominal dimensions and standard density (7,850 kg/m³). Actual weight may differ by ±2–5% due to manufacturing tolerances, rib weight on TMT bars, and section rolling tolerances. IS 1786 allows ±5% for bars ≤10mm and ±3% for bars >10mm.
As a rough estimate: residential buildings require 4–6 kg of rebar per square foot of built-up area, and commercial buildings require 6–8 kg/sqft. These are preliminary figures — actual quantities depend on structural design, span, load, and seismic zone.
No. Steel grade (Fe415, Fe500, Fe500D, Fe550D) affects mechanical properties (yield strength, elongation, ductility) but not weight. All grades of mild steel and TMT rebar have the same density of 7,850 kg/m³. A 16mm Fe500 bar weighs the same as a 16mm Fe550D bar — 1.580 kg/m.