Convert any date and time between two time zones, with the live difference — in your browser.
A time zone is not a fixed number of hours away from you: it is a rule that changes with the calendar. Half the world moves its clocks twice a year, the switch happens on different dates in the northern and southern hemispheres, and a few zones sit at half or quarter-hour offsets — India is UTC+05:30 and Nepal UTC+05:45. That is why "just add three hours" quietly fails when you schedule a call weeks ahead. This converter takes one specific date and time in one zone and gives you the exact wall-clock time in another, using the rules that apply on that particular day.
Inside, the tool reads the IANA time zone database that already ships with your browser, through the standard Intl API. The conversion uses the mirror technique: it formats a candidate instant in the chosen zone, reads back the year, month, day, hour and minute, and compares that reading with the time you typed. The gap between the two is the zone offset at that instant, and applying it pins down the exact UTC moment, which is then formatted again in the destination zone. The offset is checked a second time, so a date that falls on a daylight-saving transition resolves correctly instead of landing an hour off, and a time that does not exist — the hour skipped when clocks spring forward — is pushed forward, the same behaviour calendar apps use.
In practice it answers the questions that make remote work awkward: what 9 a.m. in São Paulo means for a colleague in Lisbon, when a 6 p.m. webinar in New York starts in Brasília, whether a deadline set in Tokyo has already passed. The two zones you pick also get a live clock, so you can glance at the current time on both sides before sending an invitation. The zone list, the offsets and the conversion all run on your device, so no dates, meetings or locations are ever transmitted.
The time you type is formatted in the source zone with Intl.DateTimeFormat and read back part by part; the difference between that reading and the candidate instant is the zone offset at that moment. Applying the offset gives the exact UTC instant, which is formatted once more in the destination zone. The offset is re-checked after the first pass so daylight-saving transitions and half-hour zones resolve correctly.
Yes. The offset is calculated for the exact date you enter, not for today, so a meeting in July and one in December are converted with the rules in force on each of those days.
From your own browser, which exposes the IANA time zone database — the same list operating systems use. Zones are shown by city with their current UTC offset.
Because some zones are offset by 30 or 45 minutes, such as India at UTC+05:30. The converter always shows the exact difference in hours and minutes.
On the night clocks spring forward an hour is skipped, so that time never happens. The converter moves it forward by the length of the gap, which is what calendars and phones do.
No. The conversion runs entirely in JavaScript on your device. No dates, zones or event names are sent to any server.
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