What does it mean?
Rebar is steel reinforcement used within concrete as part of a designed structural system. Estimating it requires more than knowing the concrete volume: bar diameters, spacing, lengths, bends, laps and layers all affect quantity. A weight-per-volume allowance can support an early budget but is not a substitute for an engineer’s details or a bar bending schedule.
In practice
Using the approximate d²/162 relationship, a 12 mm bar weighs 0.889 kg per metre. One hundred metres therefore weighs about 88.9 kg before extra length for laps or fabrication details.
Keep in mind
When preparing an estimate, record the specification reference, units and source of each assumption. Separate the net measured quantity from purchase allowances so changes remain easy to trace. Confirm product dimensions, yields and installation requirements with the supplier. Quantities do not establish structural adequacy or material suitability: use the project’s approved design and details, and seek the responsible designer’s clarification where the specification is incomplete.