Rebar Weight Calculator
Pick a bar diameter, enter length and quantity to get weight per metre, per bar and total tonnage.
Inputs
Result
Formula
| Weight per metre | w = 0.00617 × d² (kg/m, d in mm) |
| Per bar | W = w × L |
| Total | W_total = w × L × N × (1 + waste %) |
Φ12 bars, 9 m long, 100 pieces: 0.8885 kg/m → 8.00 kg per bar → 799.6 kg total, 823.6 kg or 0.824 t with 3% waste.
Standard rebar weight per metre (GB/T 1499.2)
| Size | kg per m | 9 m bar (kg) | 12 m bar (kg) |
|---|---|---|---|
| Φ6 | 0.222 | 2.00 | 2.66 |
| Φ8 | 0.395 | 3.56 | 4.74 |
| Φ10 | 0.617 | 5.55 | 7.40 |
| Φ12 | 0.888 | 7.99 | 10.66 |
| Φ14 | 1.21 | 10.89 | 14.52 |
| Φ16 | 1.58 | 14.22 | 18.96 |
| Φ18 | 2.00 | 18.00 | 24.00 |
| Φ20 | 2.47 | 22.23 | 29.64 |
| Φ22 | 2.98 | 26.82 | 35.76 |
| Φ25 | 3.85 | 34.65 | 46.20 |
| Φ28 | 4.83 | 43.47 | 57.96 |
| Φ32 | 6.31 | 56.79 | 75.72 |
FAQ
Where does the 0.00617 factor come from?
Steel density is 7850 kg/m³. A round bar of diameter d mm has area πd²/4 mm². Multiplying by density: 7850 × π × (d/1000)² / 4 = 0.006165 d², rounded to 0.00617 in practice. For Φ12 that gives 0.888 kg/m, matching the standard table.
Should lap and anchorage lengths be included?
Yes. Cut length = clear span + anchorage + lap + hook allowance. Lapped splices use 1.2-1.6 times the anchorage length depending on the lap ratio, while mechanical couplers add no bar length but add coupler count. The waste field covers this.
Why does the scale weight differ from the theoretical weight?
GB/T 1499.2 permits weight tolerance of ±6% for 6-12 mm bars, ±5% for 14-20 mm and ±4% for 22-50 mm. Because mills often roll to the negative side, a whole batch usually weighs 2-4% less than the theoretical figure.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.