Frequently asked questions (FAQ)
NIST continually broadcasts the time using shortwave radio signals from two radio stations:
• WWV near Ft. Collins, Colorado broadcasts on 2.5, 5, 10, 15 and 20 MHz
• WWVH in Kauai, Hawaii broadcasts on 2.5, 5, 10 and 15 MHzThe announcement of the time occurs at the top of each minute and states Coordinated Universal Time (UTC) so it will be necessary to adjust the hour to your local time zone.
For more information about the stations, see the Time and Frequency Radio Broadcast section.
There are two telephone numbers that allow you to listen to NIST time:
• 303-499-7111 (Colorado)
• 808-335-4363 (Kauai, Hawaii)Please note that these are not toll-free numbers. Calls from outside the local area may be subject to long-distance charges.
When calling these numbers, you will hear the same audio that is broadcast by WWV and WWVH, respectively. Note: The use of cellular phones can add a small delay to the broadcast.
There are other local time telephone services in operation. These services are not affiliated with NIST.
www.time.gov - it synchronizes with NIST every ten minutes. There is an accuracy statement based on a measurement of the round-trip network delay. This delay is measured using your computer clock as a timer each time synchronization is made. The site provides a time-of-day service, and it should not be used to measure frequency or time interval, nor should it be used to establish traceability to NIST.
You can also put a NIST clock on your own site using our time widget.
Internet Time Service (ITS) or via a telephone line (through a modem) using our Automated Computer Time Service (ACTS). Several computer operating systems have an option to automatically synchronize the computer clock to NIST time servers. Double-clicking the desktop clock should lead to the options available.
For more information, see the section on NIST radio broadcasts.
NIST web page describing WWVB radio-controlled clocks. We include links to manufacturers for additional technical support on their products.