What does rebar size mean?
Rebar size generally refers to the nominal diameter of the steel bar in millimetres. A request for “12 mm rebar,” for example, identifies the diameter but does not by itself confirm the grade, standard, length or quantity.
Common diameter range
Construction projects use different bar diameters based on approved structural specifications. The correct diameter must come from the approved structural design—not from a general online guide.
Diameter is only one part of the specification
- Grade or standard: identifies required material properties.
- Length: confirm standard or project-specific bar length.
- Quantity: state bars, bundles, kilograms or tonnes.
- Schedule: a multi-size project should list every diameter separately.
- Timing: include when the material is needed.
Avoid vague quotation requests
“Send steel price” is difficult to quote accurately. A better request is: “Please quote 12 mm deformed rebar, specified grade, required quantity, for collection or delivery on the stated date.”
Engineering safety
This guide explains purchasing terminology only. It does not determine the correct reinforcement for any structure. Use the drawings, bar-bending schedule and instructions approved by the responsible engineer.