Opening tool…
Runs in your browser. Nothing you enter is uploaded to ALCO.
About this tool.
Enter a date and time in one place and read it off in as many others as you need, with the day change and the UTC offset shown next to each. It handles the two hours a year most converters get wrong: a time that never happened because the clocks went forward is named as such, and one that happened twice because they went back lets you pick which occurrence you meant.
Using this tool.
Where do the time zone rules come from?
From your own device. Browsers ship the IANA time zone database and keep it updated with the operating system, so the answers here agree with the clock on your machine and with any rule change that has already been rolled out to it.
Why does it say a time does not exist?
Because on the morning the clocks go forward, an hour is skipped — in most of Europe 02:30 simply never occurs on the changeover date. Rather than silently pick a nearby time, the tool says so and shows the moment the clocks jumped to.
What is the "which occurrence" question about?
When clocks go back, the same hour is lived twice — once on summer time and once on standard time. Those are two different moments an hour apart, so the tool asks which one you meant instead of guessing.
Does it handle half-hour and 45-minute zones?
Yes. India at UTC+05:30, Nepal at UTC+05:45, Lord Howe Island with its 30-minute daylight saving shift — all of them come from the same database and need no special handling.
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