Time zone converter

How time zone conversion works

Every civil time on Earth is UTC plus or minus an offset. Converting is two steps: take the source offset away to reach UTC, then add the target offset. The only hard part is knowing which offset each place uses on that date, because daylight saving time moves about a hundred zones by an hour (one by half an hour) for part of the year, on dates that differ from country to country.

A worked example, winter and summer

A call at 3:00 PM in New York on January 15, 2027: New York is on EST, UTC−5, so that is 20:00 UTC, which is 8:00 PM GMT on January 15 in London, 1:30 AM IST on January 16 in India and 5:00 AM JST on January 16 in Tokyo.

The same 3:00 PM on July 15, 2027: New York is now on EDT, UTC−4, so it is 19:00 UTC. London is on BST, so it reads 8:00 PM BST on July 15; India does not change its clocks, so it is 12:30 AM IST on July 16, an hour earlier than in January. Same wall time in New York, different answers abroad. That is why this converter asks for the date.

Abbreviations are labels, not zones

EST means UTC−5 and nothing else, but New York only uses EST in winter. In summer it is on EDT (UTC−4), yet many people keep writing “EST” for any time on the East Coast. When you convert “3 PM EST” in July, ask whether the writer meant the fixed offset or New York’s clocks; the pair pages answer both. The generic names ET, CT, MT and PT avoid the problem, because they always mean the local time of the region.

Abbreviations also repeat. The IANA time zone database only uses letters “in common use among English speakers” and otherwise writes numeric labels such as +0530 or −03, so the letters alone can never identify a zone. Ambiguous ones you will meet:

Daylight saving time: skipped and repeated hours

On March 14, 2027, clocks in New York jump from 2:00 AM straight to 3:00 AM. A time such as 2:30 AM does not exist that night; the converter flags it and reads it as 3:30 AM EDT, the way most software does. On November 7, 2027, clocks go back from 2:00 AM to 1:00 AM, so 1:30 AM happens twice, first as EDT (UTC−4) and an hour later as EST (UTC−5). The converter shows the first and tells you about the second. Book overnight events for those nights with a UTC time or an explicit offset.

Countries do not change on the same day. The US moves on the second Sunday of March and the first Sunday of November (15 U.S.C. §260a). The EU moves on the last Sundays of March and October, at 01:00 GMT everywhere at once (Directive 2000/84/EC): on March 28, 2027, London goes from 1:00 to 2:00, Berlin from 2:00 to 3:00 and Athens from 3:00 to 4:00 in the same instant. That is why New York and London are 4 hours apart, not 5, for a few weeks each spring and autumn.

The southern hemisphere runs the other way. Sydney leaves daylight saving time on April 4, 2027 and starts it again on October 3, 2027, so the gap between Sydney and London changes four times a year: 11 hours in the northern winter, 9 in the northern summer and 10 in between.

Rules also change. In 2026 alone, British Columbia, Alberta, the Northwest Territories and Manitoba stopped changing their clocks, Morocco moved to permanent UTC+0, and Cuba decided not to fall back in November. Phones and browsers pick up such changes only when their time zone data is updated, which can take months. This site carries its own copy of the IANA database (tzdata) and is rebuilt with each release, so these places are correct even where your device is not.

Offsets that are not whole hours

About a dozen zones sit on a half or three-quarter hour. Converting to or from them moves the minutes too: in winter, 9:00 AM in London is 2:30 PM in India and 2:45 PM in Nepal.

The date line and three dates at once

The earliest clocks in the world are on UTC+14 (Kiritimati, Kiribati) and the latest of any place in the database on UTC−11 (Niue, American Samoa): 25 hours apart. So for one hour every day, from 10:00 to 11:00 UTC, three calendar dates are in use at the same time. It is just after midnight of the next day in Kiritimati, late evening of the previous day in Pago Pago, and the current day almost everywhere else. Conversions across the Pacific often change the date, and the converter always shows it.

Writing a time so nobody converts it wrong

• Name a city or the region’s generic zone (“3 PM New York time”, “3 PM ET”) rather than EST or EDT, unless you really mean the fixed offset.
• Add the UTC offset when it matters: “15:00 UTC−4”, or in ISO 8601 form 2027-03-14T15:00-04:00. An offset is unambiguous; an abbreviation is not.
• Use the 24-hour clock, or write “noon” and “midnight”: 12 AM and 12 PM confuse people (see AM and PM explained).
• Save calendar events in a named zone (America/New_York) so they move correctly when daylight saving time starts or ends on one side only.