What does the number assigned to a rebar size indicate?

The number assigned to a rebar size specifically indicates the diameter of the bar in eighths of an inch. For instance, if a rebar is labeled as #4, this signifies that the diameter of the rebar is 4/8 inches, which simplifies to ½ inch. This system of sizing is used consistently in the construction industry to denote standard rebar sizes, making it easier for engineers and builders to communicate specifications and ensure compatibility in reinforced concrete structures. Understanding this sizing system is crucial for proper material selection and structural integrity in construction projects.