How to Check the Official Time and Your Device’s Clock

If two clocks disagree, guessing which one is right isn’t much help. time.gov shows official U.S. time across multiple zones and compares the time on your device with its reference.

Quick answer: Open time.gov, find the time zone you need, and look at Your Device’s Clock to see the reported difference. Check the zone label as well as the clock: the correct minutes can still appear under the wrong local time if your device’s time-zone setting is wrong.

We opened the desktop site, observed its U.S. time-zone clocks and device-clock comparison, and selected the 24-hour option. An informational alert appeared; the browser connection timed out before we could verify the changed display. The image below is a historical NIST example, not the time now.

Read the zone and the time

1. Visit time.gov and allow the clocks to finish synchronizing.
2. Find your region or the zone relevant to your meeting. The page labels each clock with its time zone and UTC offset. Check the full label instead of assuming every state falls entirely within one zone.
3. Read the time and AM/PM, or choose 24-Hour Clock Display if you prefer. NIST says you can bookmark the resulting page to save that preference.

The page also displays Coordinated Universal Time (UTC). UTC is useful as a shared reference, but don’t mistake it for your local time. Regions may have different daylight-saving rules; time.gov marks areas where daylight saving is not observed. For a future appointment, confirm the date and local zone with the organizer rather than relying on today’s offset.

Compare your device’s clock

Look for Your Device’s Clock and the “Your clock is off by” reading. NIST explains that the page compares your device clock with its time reference and estimates network delay. A small displayed difference is an estimate in this browser session, not a guarantee of precision for another device or network.

If the displayed local hour seems wrong, first check the time zone and daylight-saving settings on the device. If the clock itself is wrong, use your operating system’s date-and-time settings to turn on automatic time and choose the appropriate zone where available. Settings and names vary by device; we did not change device settings for this guide. Reopen time.gov and compare again after the device synchronizes.

Know its limits

NIST describes time.gov as a time-of-day service, not an instrument for measuring time intervals or establishing measurement traceability. It estimates transmission delay; connection conditions and your device can affect what you see. The website shows a comparison—it does not automatically set your computer’s clock. For technical synchronization, see NIST’s Internet Time Service.

How we checked: We opened time.gov in a desktop browser and inspected the zone labels, UTC, and device-clock comparison. We attempted the 24-hour option, but could not verify its resulting display after the browser timed out. Screenshot source: NIST’s 2022 presentation; it is not a capture of our session.