MistriCalc → Steel Weight Calculator
Steel Weight Calculator
Rebar weight using the trade-standard d²/162 rule — per metre, per foot, and total for a full bundle of bars.
Materials & quantities explainer
Run your numbers first, then read how it works. Start with the calculator below — the example values are pre-filled — then keep scrolling for the method, a worked example and the questions builders ask most. Everything runs in your browser; nothing you type is stored.
Calculator
The weight of a round steel bar is d² ÷ 162 kilograms per metre, where d is the diameter in millimetres. A 12 mm bar weighs 0.888 kg/m (12² ÷ 162), so a 12 m bar is about 10.67 kg. For weight per foot, use d² ÷ 533. Total weight is simply weight per metre × length × number of bars.
Key takeaways
- kg/m = d² ÷ 162 (d in mm).
- kg/ft = d² ÷ 533.
- 12 mm → 0.888 kg/m; 16 mm → 1.58 kg/m.
- Total = kg/m × length (m) × quantity.
- Works for mild steel, TMT and Fe415/Fe500 alike.
How the d²/162 formula works
Weight = volume × density. For a round bar, the cross-section area is π/4 × d², and steel density is 7,850 kg/m³. With diameter in mm and length in metres, the constants collapse to a single divisor.
The exact divisor is 162.28 (from 4,000,000 ÷ (π × 7,850)); the trade rounds it to 162. The per-foot divisor 533 is just 162 × 3.281 feet per metre.
Worked example: a bundle of 10 nos. 12 mm × 12 m bars
A slab needs 10 bars of 12 mm, each 12 m long. Weight per metre = 12² ÷ 162 = 0.888 kg/m. Each bar = 0.888 × 12 = 10.67 kg. Ten bars = 10.67 × 10 = 106.7 kg ≈ 0.107 tonne. If the mill quotes per foot, 0.888 ÷ 3.281 = 0.27 kg/ft, matching 12² ÷ 533.
Standard bar weight table (kg/m and per 12 m bar)
| Diameter (mm) | Weight (kg/m) | Weight (kg/ft) | Per 12 m bar (kg) |
|---|---|---|---|
| 6 | 0.222 | 0.068 | 2.67 |
| 8 | 0.395 | 0.120 | 4.74 |
| 10 | 0.617 | 0.188 | 7.41 |
| 12 | 0.888 | 0.270 | 10.67 |
| 16 | 1.580 | 0.481 | 18.96 |
| 20 | 2.469 | 0.751 | 29.63 |
| 25 | 3.858 | 1.173 | 46.30 |
| 28 | 4.840 | 1.471 | 58.07 |
| 32 | 6.321 | 1.922 | 75.85 |
All figures use d² ÷ 162 (kg/m) and d² ÷ 533 (kg/ft).
Where this fits in your build
Use it to convert a bar schedule into ordering weight or tonnage. To estimate how much steel a slab needs in the first place (≈ 80 kg/m³), use the RCC slab calculator; for the concrete around that steel, the concrete calculator gives cement, sand and aggregate.
Frequently asked questions
What is the d²/162 formula for steel weight?
Weight per metre (kg/m) = diameter² (mm) ÷ 162. A 12 mm bar = 144 ÷ 162 = 0.888 kg/m.
How much does a 12 mm steel bar weigh per metre?
0.888 kg/m. A 12 m length weighs about 10.67 kg; per foot it is 0.27 kg.
Where does the number 162 come from?
From (π/4 × d²) × 7,850 ÷ 1,000,000 with d in mm — the constants give 162.28, rounded to 162.
How do I get weight per foot?
Use d² ÷ 533. A 12 mm bar = 144 ÷ 533 = 0.27 kg/ft, which is the kg/m figure ÷ 3.281.
How many 12 mm bars make one tonne?
A 12 m bar weighs 10.67 kg, so about 94 such bars make 1,000 kg.
Does d²/162 work for TMT and Fe500 bars?
Yes — it depends on geometry and density, not grade, so it covers mild steel, TMT and Fe415/Fe500. Allow a small rolling tolerance.
The d²/162 rule derives from the unit weight of steel (7,850 kg/m³) and the circular cross-section, and matches the sectional weights used as standard trade practice for high-strength deformed bars. Per-foot figures use d² ÷ 533 (= d²/162 ÷ 3.281). Delivered bars carry a small mass tolerance per the common site standard.
Last reviewed 2026-06-14