2 CFR 700.6: Metric system of measurement.

(a) The Metric Conversion Act, as amended by the Omnibus Trade and Competitiveness Act (15 U.S.C. 205) declares that the metric system is the preferred measurement system for U.S. trade and commerce.

(b) Wherever measurements are required or authorized, the recipient must make, compute, and record in metric system units of measurement, unless the Agreement Officer authorizes in writing that such usage is impractical or is likely to cause U.S. firms to experience significant inefficiencies or the loss of markets. Where the metric system is not the predominant standard for a particular application, the recipient may express the measurements in both the metric and the traditional equivalent units, provided the metric units are listed first.