Exact Time

How this clock gets the exact time

Your phone or computer shows the time from its own clock, which can be off. This page asks our web server for the time several times in a row. Server clocks are kept in step with atomic time using the Network Time Protocol (NTP).

Each answer is only stamped to the whole second, so a single request can’t tell the time to better than a second. The page times its later requests to land exactly when the server’s second ticks over and narrows the result from each one. After a few rounds the error is usually within a few tens of milliseconds, about the same as half the network round trip.

The status line shows how far your device clock is ahead or behind, and the large clock already includes that correction. If the server can’t be reached, the page falls back to your device clock and says so.

Why device clocks drift

Computers and phones keep time with a quartz crystal. A typical crystal is accurate to about 20 parts per million, which works out to as much as 1.7 seconds a day, or roughly a minute a month if nothing corrects it.

Most devices fix that by syncing with an internet time server every so often, so a phone is usually right to within a fraction of a second. Computers that rarely go online, devices with automatic time turned off, and some smart TVs and older laptops can drift by seconds or minutes. If this page shows a large error, turn on Set time automatically in your system settings.

US time zones and daylight saving time

The United States uses six time zones across the 50 states: Eastern (UTC−5, or UTC−4 in summer), Central (UTC−6/−5), Mountain (UTC−7/−6), Pacific (UTC−8/−7), Alaska (UTC−9/−8) and Hawaii-Aleutian (UTC−10; Hawaii itself never changes). When it is noon in New York in winter, it is 11 AM in Chicago, 10 AM in Denver, 9 AM in Los Angeles, 8 AM in Anchorage and 7 AM in Honolulu.

Daylight saving time in 2026 began on Sunday, March 8 and ends on Sunday, November 1 at 2:00 AM local time, when clocks fall back one hour. In 2027 it runs from March 14 to November 7. Hawaii and most of Arizona do not change their clocks, so Phoenix matches Denver in winter and Los Angeles in summer.

UTC, GMT and atomic time

Coordinated Universal Time (UTC) is the world’s reference time, computed from hundreds of atomic clocks. In the US, the National Institute of Standards and Technology (NIST) and the US Naval Observatory keep the official time, which you can also see at time.gov. Time zones are written as offsets from UTC, such as UTC−5 for US Eastern Standard Time.

GMT is the time zone of the UK in winter and has the same clock reading as UTC, which is why the two names are often used interchangeably. Leap seconds have occasionally been added to UTC to stay in step with the Earth’s rotation; international timekeepers agreed in 2022 to stop adding them by 2035.

Unix time, shown in the stats above, counts the seconds since January 1, 1970 00:00 UTC. Programmers use it because it is the same everywhere, regardless of time zone.