Rebar weight estimator (bar schedule quantities)
Reinforcement is ordered and priced by weight, but drawings show diameters and lengths. The standard relationship for the density of steel is d²/162 kilograms per metre with the diameter in millimetres — the number every detailer keeps in their head. This estimator applies it to a bar mark, adds the lap and wastage allowance that turns a drawn length into an ordered length, and shows the tonnage.
Rebar weight estimator
- Total weight (ordered)
- 497.2kg
- Tonnage
- 0.497t
- Weight per metre
- 1.578kg/m
- Weight per bar
- 9.47kg
- Net weight (drawn length)
- 473.5kg
- Bar cross-sectional area
- 201.1mm²
Formula
kg/m = d² / 162.2, total = kg/m × length × bars × (1 + waste)Derived from a steel density of 7850 kg/m³: (π/4)d² × 7850 / 10⁶ simplifies to d²/162.2. It holds for plain and deformed bar to every common standard, since rib volume is included in the nominal mass.
Worked examples
| Input | Result |
|---|---|
| T16 bar | 1.578 kg/m — 50 no. x 6 m = 473 kg net |
| T12 bar | 0.888 kg/m |
| T25 bar | 3.855 kg/m |
Questions
What is the weight of a 12 mm rebar per metre?
0.888 kg/m (12² ÷ 162.2). A standard 12 m length weighs 10.66 kg.
Why 162 and not 162.2?
162 is the site shorthand; 162.2 comes from the exact 7850 kg/m³ density. The difference is about 0.1%, immaterial against ordering tolerances.
How much should I allow for laps and wastage?
5% covers ordinary cutting waste on a scheduled job. Where laps are not shown on the drawing, allow 8–10%, or schedule the laps explicitly for anything priced competitively.
Does this work for mesh reinforcement?
No — fabric is ordered by sheet area and grade (A142, A252, A393). Use the sheet weight from the manufacturer's table instead.
Need a certified CAD/BIM specialist to modify or detail this drawing?
TaskBider drafters, detailers and BIM coordinators work remotely and every listing shows the pay. Typical published range for this work: $18–$45/hr.
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