The modern metric system, called the Syst me International d Unit s (or the International System of Units in English), was finalized in its current form by international agreement in 1960 and is the standard international language of measurement. It has been mandated as the preferred system of measurement in the United States since the Metric Conversion Act was passed by congress in 1975. This was further enhanced by an Executive Order in 1991 that required all government publications to be revised and that a transition plan for conversion be adapted. All federal government construction, and most states, now require metric units to be used for their projects, but not much progress has been made in the United States for total implementation of metric units for material and design used only in this country.

The United States is the last industrialized country that does not completely use the Metric system, but rather a system called inch-pound units. This appendix will provide the most currently accepted means of expressing the various metric measurement units and their abbreviations. They have been obtained from experience with various code bodies and from vendors who supply equipment to both the United States and foreign markets. In addition, a limited table of conversion factors is provided for the most often referred to units used by engineers in the construction industry. For a complete list of conversion factors, refer to standard engineering references. The abbreviations used will refer to either IP for the inch-pound units currently in use in the...