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UTC(NIST) Time Scale

Coordinated Universal Time, abbreviated as UTC, is the official, internationally agreed upon standard for world time. The National Institute of Standards and Technology (NIST) maintains its own representation of UTC, called UTC(NIST), which provides official time for the United States. This was codified into law by the America COMPETES Act of 2007, which states that the official time for the United States is Coordinated Universal Time (UTC), as “interpreted or modified by the Secretary of Commerce, in coordination with the Secretary of the Navy.” The Secretary of Commerce delegates the timekeeping responsibility to NIST, an agency of the Department of Commerce, and the Secretary of the Navy delegates the timekeeping responsibility to the United States Naval Observatory (USNO) in the Department of Defense. NIST and USNO both serve as the official U.S. timekeepers.

Of course, NIST was well established and recognized as an official United States timekeeper long before the passage of the America COMPETES Act. The first implementations of the UTC(NIST) time scale were built in the 1960s, more than half a century ago, by NIST’s predecessor, the National Bureau of Standards. In subsequent years, the time kept by UTC(NIST) became the official time reference for numerous sectors of U. S. industry, including stock exchanges and the electric power sector.

To learn more about UTC(NIST), please visit the following sections:

Section 1 – Introduction to UTC(NIST)

Section 2 – How UTC(NIST) Works

Section 3 – Performance of UTC(NIST) and UTC(NIST) Adjustments

Section 4 – Reliability of UTC(NIST)

Section 5 – Secondary UTC(NIST) Time Scales and UTC(NIST) Distribution


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Created November 18, 2020, Updated February 7, 2024