Metal · Reinforcement
TMT bar weight chart
A TMT bar weighs D²/162 kg per metre, D its diameter in millimetres: a 12 mm bar is 0.888 kg/m and 10.65 kg for a 12 m rod. An 8 mm bar is 0.395 kg/m, a 16 mm 1.58 kg/m and a 20 mm 2.47 kg/m. The chart gives every size from 6 to 40 mm per metre, per foot, per rod and how many rods make a tonne.
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Per metre
— kg/m
Per rod
— kg
Total
— kg
Cost
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TMT bar weight chart
| Diameter | kg per metre | kg per foot | kg per 12 m rod | Rods per tonne |
|---|---|---|---|---|
| 6 mm | 0.222 | 0.068 | 2.66 | 375.5 |
| 8 mm | 0.395 | 0.120 | 4.74 | 211.2 |
| 10 mm | 0.617 | 0.188 | 7.40 | 135.2 |
| 12 mm | 0.888 | 0.271 | 10.65 | 93.9 |
| 16 mm | 1.578 | 0.481 | 18.94 | 52.8 |
| 20 mm | 2.466 | 0.752 | 29.59 | 33.8 |
| 25 mm | 3.853 | 1.175 | 46.24 | 21.6 |
| 28 mm | 4.834 | 1.473 | 58.00 | 17.2 |
| 32 mm | 6.313 | 1.924 | 75.76 | 13.2 |
| 36 mm | 7.990 | 2.435 | 95.88 | 10.4 |
| 40 mm | 9.865 | 3.007 | 118.38 | 8.4 |
Nominal mass at 7850 kg/m³. IS 1786 allows a tolerance on the actual mass (larger for small diameters), so the weighbridge figure can differ by a few per cent.
Where D²/162 comes from
mass per metre = area × density = π/4 × D² × 7850 / 1 000 000
= D² / 162.2 kg/m (D in mm)
rod of 12 m = D² / 162 × 12
The area of a 12 mm bar is π/4 × 12² = 113.1 mm²; times 7850 kg/m³ and one metre, 0.8878 kg. Dividing by 162 instead of 162.2 is the site shortcut and changes the answer by about 0.1 %.
What this page does not do
- It does not take off the steel from drawings. Bar bending schedules (cut lengths, hooks, laps) are a separate job; the bar cutting optimiser nests the cut lengths into 12 m rods.
- It does not grade the steel. Fe 415, Fe 500 and Fe 550 weigh the same per metre; the grade is about strength.
Questions people ask
- What is the weight of a 12 mm TMT bar?
- 0.888 kg per metre, so a 12 m rod weighs 10.65 kg: 12² / 162 × 12.
- What is the weight of an 8 mm TMT bar per metre?
- 0.395 kg per metre; a 12 m rod is 4.74 kg.
- What is the weight of a 16 mm rod?
- 1.58 kg per metre and 18.9 kg per 12 m rod.
- How many rods are there in one tonne of 10 mm TMT?
- About 135 rods of 12 m: one rod weighs 7.40 kg.
- Why is the formula D²/162?
- Because a bar's mass per metre is π/4 × D² × 7850 / 1 000 000, which is D² / 162.2 with D in millimetres and steel at 7850 kg/m³.