Steel Weight Calculator – Rebar Weight per Meter & Total Weight
Calculate reinforcement steel weight from bar diameter, length and quantity. Quickly estimate kg per metre and total steel weight.
Introduction
The EstiMate Civil Steel Weight Calculator helps estimate the theoretical weight of round steel bars from diameter, length and quantity. It is useful for reinforcement estimation, procurement planning, BOQ preparation and checking quantities obtained from a Bar Bending Schedule.
Steel Weight Formula
For a round steel bar, theoretical unit weight is commonly estimated using Weight per metre = D² / 162.28, where D is the nominal bar diameter in millimetres. Many construction references use the rounded constant 162; the calculator uses 162.28 for its theoretical calculation.
Why the 162 Constant Is Used
The constant comes from the cylindrical volume relationship and the approximate density of steel, about 7,850 kg/m³, with unit conversions from millimetres to metres. It provides a convenient engineering approximation for the weight of a one-metre round bar.
Common Rebar Weights
Approximate theoretical unit weights are: 8 mm ≈ 0.395 kg/m; 10 mm ≈ 0.616 kg/m; 12 mm ≈ 0.888 kg/m; 16 mm ≈ 1.577 kg/m; 20 mm ≈ 2.466 kg/m; 25 mm ≈ 3.851 kg/m. Actual supplied weight can vary within applicable manufacturing tolerances.
How to Calculate Total Weight
Total Weight = Unit Weight × Bar Length × Number of Bars. For example, 100 metres of 12 mm bar has a theoretical weight of approximately 0.888 × 100 = 88.8 kg.
Steel Weight and BBS
A steel weight calculator and BBS calculator complement each other. BBS determines cutting lengths, shapes and quantities; the steel-weight calculation converts those lengths into approximate mass for procurement and costing.
Practical Uses
Use the calculator for rebar quantity checks, material ordering, preliminary BOQs, cost estimates, reconciliation and educational exercises. For procurement, reconcile theoretical weight with supplier documentation and applicable product standards.
FAQs
Q: What is the weight of 12 mm steel per metre? A: Approximately 0.888 kg/m using the theoretical formula.
Q: Is D²/162 exact? A: It is a convenient theoretical approximation. Actual mass depends on nominal dimensions and manufacturing tolerances.
Q: Can it replace a BBS? A: No. It calculates weight; a BBS provides bar-by-bar cutting and bending information.
Important Disclaimer
Use theoretical weight for estimation and checking. Project-specific reinforcement quantities, bar schedules and procurement should be based on approved structural drawings and applicable standards.