# Rebar Weight Calculator

Pick a bar diameter, enter length and quantity to get weight per metre, per bar and total tonnage.

- Page: https://jianzhujisuan.com/en/rebar-weight
- Category: Rebar (https://jianzhujisuan.com/en/c/rebar)
- Chinese version: https://jianzhujisuan.com/zh/rebar-weight.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Bar diameter Φ12, Length per bar 9 m, Quantity 100 pcs, Waste allowance 3%): **Total weight 0.824 t**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Bar diameter | select | Φ12 | — |  |
| Length per bar | number | 9 | m |  |
| Quantity | number | 100 | pcs |  |
| Waste allowance | number | 3 | % | Laps, anchorage and cutting loss, typically 2-5% |

## 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 %)

## Worked example

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.

## Questions

### 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.

## Related tools

- [Rebar Anchorage Length Calculator](https://jianzhujisuan.com/en/rebar-anchorage): Basic and seismic anchorage length from bar grade, diameter and concrete class.
- [Rebar Lap Length Calculator](https://jianzhujisuan.com/en/rebar-lap): Lap length ll / llE by splice percentage, plus the permitted number of splices.
- [Rebar Cut Length Calculator](https://jianzhujisuan.com/en/rebar-cut-length): Cut length and bar weight with standard hook allowances.
- [Rebar Spacing and Bar Count Calculator](https://jianzhujisuan.com/en/rebar-spacing): Bars and actual spacing from run length and design spacing, with total weight.
- [Stirrup Length and Count Calculator](https://jianzhujisuan.com/en/rebar-stirrup): Stirrup length, count and weight with the 11.9d seismic hook allowance.
- [Rebar Mesh Weight Calculator](https://jianzhujisuan.com/en/rebar-mesh): Weight per square metre and total mesh weight from dimensions and spacings.

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