Time Zone Converter
Pick a zone, date and time, then see the same moment in every city on your list — daylight-saving aware, with day changes flagged.
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About this tool
"Is 9 am in London 4 am or 5 am in New York this week?" The answer changes twice a year, and the US and Europe don't even switch on the same weekend. This free time zone converter takes the guesswork out of scheduling calls, webinars and flights across time zones: choose a source zone, enter the date and time, and every city on your list updates at once with its UTC offset (such as GMT+9) and a clear +1 day or −1 day badge when the calendar date differs. Because it uses the IANA time zone database built into your browser rather than a hard-coded table, daylight-saving transitions, half-hour zones like India and even quarter-hour zones like Nepal are handled correctly.
Your browser's own zone is detected automatically and the form starts at the current moment, so a single click answers "what time is it there right now?". Add the cities your team or family live in and the list is remembered on this device. Everything runs in your browser — no account, no server, no tracking of what you convert.
How to convert between time zones
- Choose the source time zone and enter the date and time you want to convert (or press Now).
- Read the converted time for each zone in the To list, noting the offset and any +1 / −1 day badge.
- Add cities by typing a name, or remove ones you don't need — your list is saved for next time.
Frequently asked questions
Does the converter handle daylight saving time?
Yes. It uses the time zone database built into your browser, which knows the daylight-saving rules for every IANA zone, so the same wall-clock time in New York converts differently in January and July. Always enter the actual date of the event, not just the time, so the right rule applies.
What does +1 day or −1 day mean next to a result?
The converted time falls on a different calendar day than the time you entered. For example, noon in New York is 1:00 the next morning in Tokyo, so Tokyo shows +1 day. It is the most common source of missed calls across the Pacific, which is why it is flagged separately.
Why are zones named after cities instead of abbreviations like EST or CET?
Abbreviations are ambiguous — CST is used for Central Standard Time in the US, China Standard Time and Cuba Standard Time — and they do not say whether daylight saving applies. The city-based IANA names such as America/Chicago are unambiguous and carry the full DST history, so converters, calendars and operating systems all use them.
Can I keep my own list of cities?
Yes. Add or remove target zones with the controls under the list; your selection is saved in your browser's local storage on this device, so it is there the next time you open the page. Nothing is sent to a server, and clearing site data resets the list to the defaults.
Which zone does the tool start from?
It detects your device's zone from the browser settings and preselects it with the current date and time. You can switch the source to any other zone — handy when a meeting invite says 9 am London and you need to know what that is for the rest of the team.