Timezone Converter – Convert Time Between Zones

How a timezone converter handles UTC offsets and DST

A timezone converter maps a civil clock time in one IANA zone onto the equivalent instant in another. The world uses offsets from Coordinated Universal Time (UTC): India at UTC+5:30 is five and a half hours ahead of UTC, while US Eastern standard time is UTC−5. Those offsets are why the same meeting can be 09:00 in one city and 14:00 in another.

Daylight saving time changes offsets seasonally in many regions, so a fixed “plus five hours” rule is often wrong around spring and autumn transitions. This timezone converter uses the browser IANA database via Intl.DateTimeFormat, so DST, half-hour offsets, and historical rule changes apply to the date you enter.

When you convert timezone for an international invite, name both zones in the message. Use the timezone converter to align participants, then put explicit zone names or a UTC timestamp in the calendar event so nobody has to guess.

DST transitions create “missing” or “duplicate” hours once a year. Confirm whether a meeting uses local wall-clock time or a UTC timestamp. Aviation and trading systems often standardize on UTC internally; this timezone converter can show both the local result and the UTC equivalent by setting one side to UTC.

Typical uses: scheduling a call across continents, checking a flight arrival in local time, reading a log timestamp against a colleague’s zone, or converting a webinar start time before you add it to your calendar. Pair this timezone converter with the date-difference calculator when a multi-day span also crosses a DST shift.

The dropdowns cover major business cities plus UTC. For a route you use every week, open one of the city-pair pages linked below — each is a focused timezone converter for that corridor, with the live offset, sample meeting hours, and a reverse link. The hub on this page is the general timezone converter: any date, any pair among the listed zones, DST included.

A common mistake is converting the time but forgetting the calendar date. Crossing the International Date Line, or converting evening hours in the Americas into the next morning in East Asia, changes the day as well as the clock. Read both result cards before you send the invite. If you also need how many days sit between two dates, use the date-difference calculator after you convert timezone.

How to read the result

Type the date and time as it reads on the clock in the “from” zone — the label shows which zone that is — and the converter shows the same moment in the “to” zone, with the date, because converting evening times across the Atlantic or Pacific often lands on a different day. The input always means wall-clock time in the source zone, whatever time zone your own computer is set to.

Times that do not exist or happen twice because of daylight saving are handled predictably: 02:30 on the night New York springs forward is treated as 03:30 on the new offset, and 01:30 on the night it falls back is the first of the two 01:30s.

Worked examples

• 09:00 in New York on 15 January is 14:00 in London and 23:00 in Tokyo.
• 09:00 in New York on 15 July is still 14:00 in London — both observe summer time — but 22:00 in Tokyo, which does not.
• In the weeks between the US and European clock changes (mid-March and late October to early November), New York and London are only 4 hours apart instead of 5.
• India is UTC+5:30 all year, so its offset to other zones includes half an hour; Nepal is UTC+5:45.

Scheduling across time zones

• Put the time in every participant’s zone in the invitation, or anchor it to UTC, and name the zones (“10:00 New York / 15:00 London”) rather than writing EST or BST, which are often used incorrectly.
• Calendar apps store events in UTC and convert for each attendee; a time zone set wrongly on one person’s device is the usual cause of “I joined an hour late”.
• For recurring meetings, check the weeks around daylight-saving changes, when the gap between regions moves by an hour.