How to calculate rebar weight
Reinforcement bar weight per metre is found with the well-known D²/162 rule, where D is the bar diameter in millimetres:
Weight (kg/m) = D² ÷ 162
This comes from the circular cross-sectional area (π/4 × D²) multiplied by the density of steel (7,850 kg/m³). Multiply the weight per metre by the bar length and the number of bars to get the total weight.
Rebar weight chart (kg per metre)
| Bar diameter | Weight (kg/m) | Per 12 m bar |
|---|---|---|
| 8 mm | 0.395 | 4.74 kg |
| 10 mm | 0.617 | 7.40 kg |
| 12 mm | 0.888 | 10.66 kg |
| 16 mm | 1.578 | 18.94 kg |
| 20 mm | 2.466 | 29.59 kg |
| 25 mm | 3.854 | 46.25 kg |
| 32 mm | 6.313 | 75.76 kg |