Time Zone Converter

Why the converter asks for a date

The gap between two cities is not a constant. New York is normally five hours behind London, but the United States changes its clocks on the second Sunday of March and the first Sunday of November, while Europe changes on the last Sunday of March and of October. For two or three weeks in March and one week in autumn the gap is four hours. Across the equator the swing is larger, because the seasons are reversed: Sydney is 11 hours ahead of London in January, 9 hours ahead in July and 10 hours ahead in the weeks between the two changes.

Times that do not exist, and times that happen twice

When clocks jump forward, an hour of local time is skipped. In New York, 02:30 on 8 March 2026 never appears on any clock, and the converter tells you so instead of guessing. When clocks go back, an hour is repeated: 01:30 on 1 November 2026 happens twice in New York, an hour apart. The converter then asks whether you mean the earlier or the later occurrence. The meeting that moved follows one such invitation through a clock change.

Place names instead of abbreviations

The lists use names such as America/New_York or Asia/Kolkata from the IANA time zone database. A name carries the full set of rules for that place, past and future. An abbreviation only describes one offset in one season, and many are ambiguous: CST can mean Central Standard Time in North America, China Standard Time or Cuba Standard Time, and IST is used for India, Ireland and Israel. Not every offset is a whole hour either: India is 5 hours 30 minutes ahead of UTC and Nepal 5 hours 45 minutes.

Sharing a time with other people

“Copy share link” puts the date, time and places into the address, so whoever opens it sees the same conversion, in their own language if they switch. “Save 1-hour event” downloads a calendar file that stores the instant in UTC; each person’s calendar then shows it in its own local time. For a recurring meeting, create the series in your calendar app, in the time zone of the person whose local time should stay fixed.

Questions and answers

Is UTC the same as GMT?

For everyday planning, yes: the two show the same clock time. UTC is the international standard kept by atomic clocks and never changes with the seasons. GMT is the name of the time zone used in the United Kingdom in winter. London itself moves one hour ahead of UTC in summer.

What is a good time for a call between Europe, America and Asia?

No hour suits all three. Europe and the Americas overlap when it is afternoon in Europe; Europe and Asia overlap when it is morning in Europe. With all three, someone is outside office hours: 08:00 in San Francisco is late afternoon in London and close to midnight in Singapore. Teams that meet regularly often rotate the inconvenient slot.

Does the converter know about future rule changes?

It uses the time zone data built into your browser. Governments sometimes change their rules with only a few weeks’ notice, and a device that has not been updated will not know. Keep your browser and operating system up to date, and check an important conversion again shortly before the day.

Which dates can I convert?

Any date from 1900 to 2100. Past dates follow the historical rules recorded in the time zone database; future dates follow the rules in force today.

Calculations run in your browser. No account is needed, and your inputs are not sent to our server. Read how our clocks work.