About The Personal World Clock – Applet Version

It is recommended that your computer is enabled with an up-to-date browser when using the Personal World Clock applet version.

Go directly to the Personal World Clock ― Applet version. Snapshot of Personal World Clock ― Applet version


Java support must also be enabled. If Java is not installed in your browser, you can download it from java.com. Look below in the Troubleshooter section for more details.

If the applet version does not work or you are not allowed to enable or install Java, please use the regular Personal World Clock instead.

User registration recommended

Although most of the functions are available without registration, it is recommended that you register and is log in. User registration will allow access to additional functions and your settings will not be lost if you change to another computer or your browser's cookies are lost.

How to use the Personal World Clock

If you have never used the Personal World Clock before, there will be no cities displayed. On the Personal World Clock - Applet Version page, please click the "Setup..." button to add cities to your Personal World Clock. Please click the "Setup..." button to add cities to your Personal World Clock.

Main clocks display

Once configured, the applet will display your clocks. Depending on how many cities you have selected and your configuration, the clocks will be shown in a grid with many columns and rows. If you click on a city, you will see detailed information about it. This option is available only when your Personal World Clock does not have unsaved changes. After clicking an individual location, you can use the Back button on your browser to return to the complete clock display.

Home location time

If you have configured a home location in the Site configuration, it will be displayed below the main clocks.

UTC/GMT time

Current Universal Coordinated Time (UTC) or Greenwich Mean Time (GMT) will always be shown below the clocks.

"Info" button

Clicking this button changes the applet to show usage information about the Personal World Clock. Clicking “Info” again will reset the applet to your personal clock display.

The "Synchronize status" below the middle of the applet gives a clue to the clock’s accuracy. The time difference displayed is the maximum error that the clock was believed to have had when it was loaded or last synchronized. You can click the “Synchronize” button to synchronize again. The difference will generally not go below 0.2 seconds unless you have a very fast Internet connection. You can read more about clock accuracy here.

Click "Info" again to come back to the clock display.

"Share" button

If you like, you can share most of your setup with other users. Click the "Share" button, and the address (URL) will appear in the applet. Click the URL to see the shared version of the clock. Highlight the URL in your browser to copy it, then you can either bookmark it, e-mail it or link to it from your web site.

Please note that only your locations will be available in this shared version. If you have made any other changes under "Other options" or added alternative names or notes for a location, they will not be available in the shared version.

If you are not able to save your settings, you can bookmark the URL shown here and use it later, as it does not require cookie support in your browser.

Click "Share" again to reset the applet to your personal clock display.

"Setup..." button

The "Setup..." button opens a new window where you can configure cities and other settings for your clock. More details about the Personal World Clock configuration are available on the Configuration help page.

"Synchronize" button

Click this button to synchronize the applet clock with the server clock. You normally do not need to do this, as the clock is automatically synchronized when it is loaded. Read more about clock accuracy here.

"Save" button

This button will be available if you have made any changes in the “Setup…” window. Click this button to have your current settings saved until next time you make changes.

If for some reason you are not able to save your settings, please press the "Share" button and bookmark the address given there.

How accurate is the Personal World Clock?

Click the "Info" button to show any errors of the clock at the time it was loaded. If your computer clock is running slow or fast or is altered in any way, the Personal World Clock will also be affected. Click the "Synchronize" button to re-synchronize the clocks.

Background details

Your computer clock does not have to be correct, as the clock synchronizes with the web server to show the correct time. The web server in turn is synchronized with reliable atomic clocks through an Internet protocol called Network Time Protocol (NTP). Each synchronization introduces a small error, depending on factors such as the network latency between the two computers’ synchronization, the accuracy of the source computer's clock and the demands on each computer.

In most network conditions, the error will be on a sub-second level, but on slow or congested networks, the error could be seconds long. The Personal World Clock is not intended for high-precision milli- or microsecond accuracy; for those purposes, specialized hardware should be considered instead.

After the initial clock synchronization, the applet uses your local computer clock to advance the seconds and minutes. It remembers how large the difference was between your computer clock and the server clock. For instance, if your computer clock runs one second slower every hour, the Personal World Clock will do so as well. Once every 24 hours, the Personal World Clock will re-synchronize automatically to avoid significant time loss.

Using the Personal World Clock to adjust a watch, wall clock or other device

It is recommended that you click the "Synchronize" button before using the Personal World Clock to adjust other clocks.

Using the clock to adjust your computer clock

Since the Personal World Clock depends on your local system clock to advance its seconds, any changes made to the local system clock will affect the Personal World Clock. For example, if your computer clock is manually advanced by one minute, the Personal World Clock will also jump one minute.

Therefore, please click the "Synchronize" button every time you have made a change to your system clock.

The Personal World Clock is able to detect some local adjustments and will give a message reading "Please resynchronize" when it detects that the local system clock has been altered.


Here are suggested solutions for some problems.

Startup problems

If you do not see the applet, check to make sure you have a Java-enabled browser and that you have configured the browser to support Java applications. Java is available for download from java.com.

The Java applet contacts the timeanddate.com web server in order to synchronize, retrieve data and save settings, so firewall settings must allow HTTP traffic (port 80 to www.timeanddate.com) and DNS lookups. Network Time Protocol (NTP) does not have to be open.

If you have taken the above steps and the applet still doesn’t show up, you may be behind a company firewall that filters out Java applets. Remember that many computers have a software firewall in addition to any other firewalls.

If the applet loads incorrectly, it might show one of these codes:

  • "Error code: D1"
  • "Error loading cities Error code: D2"
It is likely that firewall settings block the Java applet's attempts to connect with the timeanddate.com server.

Not able to save

You might see an error message that says, "Error during save (Error code: S1)" (or S2 or S3). Please try to use the normal configuration page and save there, and then return to the Personal World Clock applet version.

Settings are lost

If your settings disappear, this could be because the cookie used to store your information was lost. Read how to troubleshoot cookies or consider registering to store your settings permanently.

If you are registered but the old settings have disappeared, please check the top of the page to see if you are still logged in.

The Personal World Clock does not show the correct time

If the time for all locations is incorrect, please click the "Synchronize" button.

If you believe that the time zone for a location is incorrect, please check that you have selected the right location (some locations have similar names but are in different time zones). If the location is correct, please use the feedback e-mail at the bottom of the page to report the error. Please provide as many details as possible.

Topics: Help

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