What nominal size does a #9 bar represent?

A #9 bar represents a nominal diameter of 1 1/8 inches. The designation of rebar sizes, such as #9, follows a standard system where the number indicates the bar's diameter in eighths of an inch. Specifically, to determine the diameter of a #9 bar, you divide the number 9 by 8, resulting in 1.125 inches, which is equivalent to 1 1/8 inches.

Understanding this sizing system is crucial for ensuring the correct specifications in reinforcement designs, concrete mix, and structural calculations. It helps in predicting the load-bearing capacity, which is vital in maintaining the structural integrity of reinforced concrete elements, such as beams and slabs.

Being familiar with rebar sizing is essential for professionals in the construction and engineering fields, as it directly relates to compliance with building codes and project safety requirements.