Derivation of the D² / 162.2 TMT Bar Weight Formula (IS 1786:2008)
Deterministic Engineering Equation (IS 1786 / IS 2502)
Unit Weight (kg/m) = D² ÷ 162.2 | 12m Full Rod Weight (kg) = (D² ÷ 162.2) × 12
The cross-sectional area of a cylindrical steel bar of diameter D mm is (π/4) × D² mm² = (π/4) × D² × 10⁻⁶ m². Multiplying by the standard steel density of 7,850 kg/m³ gives Weight/m = 0.785398 × 7850 × 10⁻⁶ × D² = D² × 0.0061654 = D² / 162.196 ≈ D² / 162.2 kg/m. In site practice, 10 to 13 kg of 16-SWG annealed black binding wire is required per 1 Metric Tonne (1,000 kg) of tied reinforcement.
Official IS 1786 TMT Bar Weight Chart (Per Meter, Per 12m Rod & Rods Per Tonne)
Use the verified 2026 commercial procurement and site-execution benchmarks below when reviewing contractor quotations across Noida, Greater Noida, Gurugram, New Delhi, Faridabad, and major Indian metros:
| Specification / Grade | Governing Standard | 2026 Benchmark Rate / Constant | Engineering Application & QA Hold-Point |
|---|---|---|---|
| 8 mm Fe550D TMT | IS 1786 (±7% Tol.) | 0.395 kg/m • 4.74 kg / 12m rod | ~211 Rods per Metric Tonne | 135° seismic stirrups & slab temperature mesh. |
| 10 mm Fe550D TMT | IS 1786 (±5% Tol.) | 0.617 kg/m • 7.40 kg / 12m rod | ~135 Rods per Metric Tonne | Two-way RCC floor slabs, chajjas & lintel bars. |
| 12 mm Fe550D TMT | IS 1786 (±5% Tol.) | 0.888 kg/m • 10.66 kg / 12m rod | ~94 Rods per Metric Tonne | Heavy commercial slabs, retaining walls & footing mats. |
| 16 mm Fe550D TMT | IS 1786 (±3% Tol.) | 1.578 kg/m • 18.94 kg / 12m rod | ~53 Rods per Metric Tonne | Primary floor beams, columns & staircase waist slabs. |
| 20 mm / 25 mm / 32 mm | IS 1786 (±3% Tol.) | 2.466 / 3.853 / 6.313 kg/m | 33 / 21 / 13 Rods per MT (12m) | High-rise columns, pile caps & deep raft foundations. |
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