TMT Bar Weight Chart
Weight per metre, weight per 12 metre bar, bars per tonne — and the rolling margin trick that quietly costs you steel.
| Diameter | Area (mm²) | kg / metre | kg / 12 m bar | Bars / tonne |
|---|---|---|---|---|
| 6 mm | 28.3 | 0.222 | 2.66 | 376 |
| 8 mm | 50.3 | 0.395 | 4.74 | 211 |
| 10 mm | 78.5 | 0.617 | 7.40 | 135 |
| 12 mm | 113.1 | 0.888 | 10.66 | 94 |
| 16 mm | 201.1 | 1.580 | 18.96 | 53 |
| 20 mm | 314.2 | 2.470 | 29.64 | 34 |
| 25 mm | 490.9 | 3.850 | 46.20 | 22 |
| 28 mm | 615.8 | 4.830 | 57.96 | 17 |
| 32 mm | 804.2 | 6.310 | 75.72 | 13 |
| 36 mm | 1017.9 | 7.990 | 95.88 | 10 |
| 40 mm | 1256.6 | 9.860 | 118.32 | 8 |
Rolling margin — the number nobody checks
IS 1786 allows the actual weight of a bar to fall below the nominal figure by a set tolerance: up to 7% on 8 mm and 10 mm, 5% on 12 mm and 16 mm, and 3% above 16 mm, measured on individual samples.
That tolerance is legal. It is also money. A supplier consistently rolling at the bottom of the band on 8 mm bar is delivering roughly 70 kg less steel in every tonne you pay for, and your bar bending schedule will run short at exactly the wrong moment.
We hold our despatch weight inside ±2% of nominal and check it on our own weighbridge before the trailer leaves. Ask any supplier for their weighbridge slip. The ones who hesitate are telling you something.
How to check weight on site
- Take a full 12 metre bar, not an offcut.
- Weigh it. Compare against the kg per 12 m column above.
- Repeat on three bars from three different bundles.
- If the average is more than 3% light, raise it before you unload the rest.
