Enter a rebar diameter and total bar length to estimate reinforcement steel weight instantly. The calculator shows kg, tonnes and pounds, then explains the unit-weight method so you can audit the result.
Enter values and calculate.
For ordinary carbon-steel reinforcing bar, a practical estimating formula is unit mass ≈ diameter² ÷ 162.28, where diameter is in millimetres and the result is kilograms per metre. Total weight is then unit mass × total length. This is a geometric mass estimate and should not be confused with a mill test weight or a supplier's exact delivered mass.
| Diameter | Approx. kg/m | Typical use |
|---|---|---|
| 8 mm | 0.394 | Light reinforcement |
| 12 mm | 0.887 | Slabs and secondary reinforcement |
| 16 mm | 1.577 | General structural reinforcement |
| 20 mm | 2.465 | Heavier beams and columns |
| 25 mm | 3.851 | Heavy reinforcement |
| 32 mm | 6.310 | Large structural members |
Weight changes with the square of diameter. Doubling diameter therefore produces roughly four times the cross-sectional area and approximately four times the mass per metre. This makes diameter a critical variable when checking reinforcement schedules, transport weights and procurement quantities.
For 120 m of 16 mm bar, the estimated unit mass is about 1.577 kg/m. The resulting steel mass is approximately 189.2 kg. If the project contains 50 identical 2.4 m bars, the same total length can be entered as 2.4 m and 50 bars.
This calculator does not account for couplers, chairs, tying wire, fabrication tolerances, mill-specific mass variation or additional length created by bends and hooks. For procurement, use the approved bar schedule and supplier documentation. For structural design, use the governing project specification and engineer-approved reinforcement details.
A common estimating formula for steel reinforcing bar is diameter² ÷ 162.28 when diameter is in millimetres.
Yes. Divide kilograms by 1,000. The calculator displays both kilograms and tonnes.
Only if the additional lap length is included in the total length you enter. It does not automatically infer laps.
This version uses millimetres and metres to reduce conversion errors. Convert inch dimensions before entering them.
No. It is an estimating calculation based on nominal diameter and theoretical unit mass.