World time converter
Pick a reference time and time zone to see the local time and offset of 90+ cities at once, with daylight saving handled and a live search.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Reference time and zone
Conversions use the IANA time zone database through Intl.DateTimeFormat and follow daylight saving time automatically; “Now” is read in the reference zone.
Local times
Press “Now” or enter a reference time to see every city at once.
What this tool does
- Set one reference time and zone before a cross-border meeting, interview or stream, and see the local time and offset of 90 cities at once instead of miscounting by an hour.
- Check whether a city is asleep: the table flags day or night (06:00–17:59 counts as day) and shows the date delta versus the reference zone.
- Debug "but they said tomorrow" situations — the date column gives -1 / 0 / +1 directly instead of making you do the mental arithmetic.
- Copy the whole table (tab-separated) into Excel or a ticket; far faster than looking up each time zone by hand.
Example
Input
Reference time 2026-01-02 09:30, reference zone Asia/Shanghai
Output
Beijing 2026-01-02 09:30:00 +08:00 0h Daytime Same day London 2026-01-02 01:30:00 +00:00 -8h Night Same day New York 2026-01-01 20:30:00 -05:00 -13h Night Previous day Los Angeles 2026-01-01 17:30:00 -08:00 -16h Daytime Previous day
This mirrors the Copy all output (city, country, local time, UTC offset, difference, day/night, date) with 4 of the 90 rows shown. January is winter time, which is why London reads +00:00 and New York -05:00.
Frequently asked questions
Is daylight saving handled automatically?
Yes. Conversion goes through the IANA time zone database and Intl.DateTimeFormat rather than hard-coded offsets. The same reference time differs between January and July: 2026-01-02 09:30 in Shanghai puts London at +00:00, while 2026-07-02 09:30 puts it at +01:00 and moves New York from -05:00 to -04:00.
What time formats are accepted?
Use YYYY-MM-DD HH:mm, optionally with :ss, and T is accepted instead of the space (2026-01-02T09:30). A bare 09:30 is rejected. The value you type is interpreted in the reference zone selected above, not in your own time zone.
My city is not in the list — what now?
Type any IANA zone name into the custom zone field (for example Asia/Kathmandu or Pacific/Fiji); it changes the reference zone used for the calculation, while the table itself always lists the built-in 90 cities. An unknown zone name is reported instead of silently falling back.
Why is the result an hour off from my phone world clock?
Usually this happens near a DST switch, or when a country changed its rules. The tool uses the time zone database shipped with the browser, so an old system with stale tzdata can lag behind the latest rules. Press "Use my zone" to reset the reference to your own zone and re-check.
Is the date and time I enter uploaded?
No. All conversion happens in your browser, the page makes no network requests, it works offline, and the reference time you enter is never recorded.
Keywords：world timetime zone convertertimezoneworld clockutc offset世界时间时区转换时差夏令时世界时钟