See the current time across multiple cities and time zones at once, and convert a specific time from one zone to any others — handy for scheduling calls across countries.
Time zones are political, so some offsets land on 30 or 45 minutes (India +5:30, Nepal +5:45). Whether daylight saving applies — and on which dates it flips — varies by country, so an offset worked out in March or November may not hold a few days later.
In theory each 15° of longitude is an hour. In practice the boundaries follow borders and administrative convenience.
China spans five theoretical zones and uses one (UTC+8). In the far west, summer sunsets fall close to 10pm.
Thirty and forty-five minute offsets exist — India (UTC+5:30), Iran (+3:30), Nepal (+5:45), central Australia (+9:30).
Mental arithmetic from longitude therefore fails often. Checking by city name is the reliable approach.
Regions observing DST change their offset twice a year. The gap between New York and London is five hours most of the time — and briefly four or six, because the two change on different dates.
The US switches on the second Sunday in March and the first Sunday in November; the EU on the last Sundays of March and October. The weeks in between run on unusual offsets.
The southern hemisphere is inverted — Australia, New Zealand and Chile observe DST during the northern winter.
Japan, China, India and Korea do not observe it at all.
This tool uses the browser's IANA time zone database, so it reflects the rule actually in force on that date.
Never write just "10am". Always attach the zone — "10:00 EST".
Writing in UTC is safest, since it is the one reference unaffected by daylight saving. "14:00 UTC" is the same instant everywhere.
Watch the date boundary. 9am in Seoul is the previous evening in New York, so "Tuesday's meeting" may be Monday for the other party.
For Asia–US calls the practical overlaps are early morning in Asia against late afternoon US Eastern, or late evening in Asia against morning US Eastern.
Crossing the International Date Line changes the date by one day — forward going west, back going east.
The line is not straight; it detours around territories. Kiribati moved it east in 1995 so the whole country would share a date.
That produces extreme spans: Kiribati (UTC+14) and Howland Island (UTC−12) are 26 hours apart — two calendar days coexisting.
Samoa skipped 30 December entirely in 2011 to align its dates with Australia and New Zealand.
UTC is the atomic-clock-based international standard. GMT is the historical Greenwich Mean Time; in everyday use they are treated as equivalent.
Do not trust abbreviations. CST can mean US Central Time (UTC−6), China Standard Time (UTC+8) or Cuba Standard Time (UTC−5).
IST is shared by India (+5:30), Ireland and Israel.
This is why technical documents and calendars use UTC offsets or IANA identifiers (Asia/Seoul) instead.
Using the browser's Intl.DateTimeFormat with IANA time zone data. No external API, so it works offline.
Time zone rules change by government decision, several times a year worldwide. Browser updates refresh the data — a very old browser may not know about recent changes.
Search for a city or region and add it; your chosen zones are saved for next time.
Yes — it uses the browser's time zone data, so DST is applied automatically per region.
Add everyone's city, then adjust the reference time until you find a slot that lands in reasonable hours for each location — daylight saving is factored in automatically.
What this tool bases its numbers on, and how far those numbers go.
Every city is an IANA time zone identifier (Asia/Seoul, America/New_York). One absolute instant is formatted into each zone with Intl.DateTimeFormat, so daylight saving and historical offset changes come from the runtime's data rather than from arithmetic on a fixed offset.12:00 UTC is 21:00 in Asia/Seoul, which is UTC+09:00 all year. The same instant is 08:00 in America/New_York while US daylight saving is in effect (UTC−04:00) and 07:00 outside it (UTC−05:00).