Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

New Web Site Puts Atomic Time on Your Computer

The official U.S. time in any U.S. time zone now can be obtained from the new Internet web site,, maintained by the Boulder Laboratories of the National Institute of Standards and Technology, an agency of the Commerce Department's Technology Administration.

This public service is provided jointly by the two federal agencies that provide the nation's time services: NIST and the U.S. Naval Observatory. Both contribute time from their respective atomic clocks to an international pool that is used to define Coordinated Universal Time (abbreviated UTC from its French name), the official world time. The two clocks should never differ by more than one ten-millionth of a second.

Because of the complexities of international time zones and daylight-saving time, provides local time for U.S. locations only. For times outside the United States, links are offered to a UTC display and an international time zone web site (via the "About This Service" page).

Most users will receive a time reading accurate to much better than one second.

Released October 14, 1999, Updated January 20, 2023