Rebar weight calculator
Calculate the weight per metre and the total weight of reinforcing bar from its nominal diameter and total length.
How it is calculated
Weight per metre (kg/m) = d² ÷ 162, with d in mm. Total weight = kg/m × total length in metres.
Worked example
12 mm bar, 100 m: 12² ÷ 162 = 0.8889 kg/m, total = 88.89 kg.
Steps
- Enter the nominal bar diameter from the bar schedule.
- Enter the total length for all bars of that size, including laps.
- Read the total weight and add an allowance for cutting waste.
Frequently asked questions
Where does d² ÷ 162 come from?
Steel density 7850 kg/m³ times the area of a circle, π d² ÷ 4, gives 0.006165 d² kg/m, which is the same as d² ÷ 162.
Is this the same for deformed bars?
Yes. The nominal diameter is defined so that the weight matches the plain-bar formula.
Should I include laps and hooks?
Yes. Add lap splices and bent hook lengths to the total before ordering.
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References
Nominal mass of reinforcing bar from ASTM A615 (bar sizes and nominal weights) and ISO 6935-2 (steel for reinforcement).
Estimates for information only. Verify critical values with a qualified engineer or your supplier standards.