| Reinforcing Bar: Inches or Millimeters?
Today, the inch-pound and the metric measurement systems co-exist throughout the U.S. construction industry. Virtually all federally funded construction is being designed and built using the metric system.
Starting in 1997, CRSI member steel mills took the initiative to convert to "soft metric" reinforcing bar production - which enables the industry to furnish the same reinforcing bars to inch-pound construction projects as well as to metric construction projects.
"Soft metric" means that units in these two systems of measurement can be used to designate the same regularly used, equivalent sizes of construction materials. The sizes of the bars have not changed. The metric sizes correspond exactly to inch-pound sizes.
From the Manual of Standard Practice:
ASTM Standard Inch-Pound Rebar table ASTM Standard Metric Rebar table