Time zone converter

Converting a time between zones looks like simple arithmetic, until daylight saving time gets in the way. New York is five hours behind London for most of the year, but four hours behind for a few weeks in March and October, because the United States and Europe change their clocks on different Sundays. India is five and a half hours ahead of London in summer and five and a half hours ahead of GMT all year, Nepal keeps a quarter hour of its own, and a call at 4 pm in California is already the next morning in Sydney. This converter does the arithmetic for the date you choose. Write the whole question in one line, such as "9:30 am PST to IST", or add places one at a time: a town from the search box, a time zone abbreviation, a UTC offset, an IANA name such as Europe/Berlin, or any point you click on the map. Each place gets its own time field, so you can change the time where you are or where the other person is, and the rest follow. Places on another day are marked +1 or −1. The map shows where it is day and night at that moment, and the meeting planner below lists the whole day hour by hour, so you can see which hours fall in everyone's working day.

How to use it

1. Type a time and the places in the top box, such as "3pm EST to CET, Tokyo", and press Convert.
2. Or add towns, time zones (EST, CET, UTC+5:30, Asia/Tokyo) or points on the map one at a time.
3. Change the date, or the time in any place; every other place shows the same moment.
4. Use the meeting planner to find hours that suit everyone, then copy the list as text, save it as CSV or copy the share link.

How accurate is it?

Daylight saving time on the date you choose

The converter turns the time you type into one instant and then reads the clock in every other place at that instant, using the IANA time zone database built into your browser – the same rules phones and servers use. That is why the answer is right on dates when only one of two places has changed its clocks, such as the weeks in March and late October or early November when Europe and North America are out of step, and in the southern hemisphere, where summer time runs from about October to April. When a country changes its rules, the converter is right as soon as your browser has been updated.

Abbreviations are fixed offsets

EST means Eastern Standard Time, UTC−5, and that is how the converter reads it, also in July. Most people who write "3pm EST" in summer mean the clock in New York, which is then on EDT, UTC−4. When that happens, the converter says so under the list; write ET (Eastern Time) or New York to follow the local clock instead. The same goes for PST/PDT, CET/CEST, BST and the other abbreviations with a season in their name. ET, CT, MT, PT and UK follow the clock of New York, Chicago, Denver, Los Angeles and London through the year.

Towns and points on the map

A town or a point on the map gets the time zone of the place, from the timezone-boundary-builder polygons built from OpenStreetMap. The boundaries are simplified for the browser and are correct to within about 1 km; for a town close to a zone boundary, such as on the border between Indiana's two zones, check the point on the time zone map. Out at sea, a point gets the nautical time zone for its longitude.

Good to know

One abbreviation, several zones

IST is India Standard Time (UTC+5:30) here, but the same letters are used for Irish Standard Time and Israel Standard Time; CST is taken as Central Standard Time in North America, not China or Cuba; AST is Atlantic Standard Time, not Arabia. If you mean one of the others, type a town or a UTC offset instead – the label in the list shows how each place was read.

A time that does not exist, or happens twice

When the clocks go forward, an hour is skipped: 2:30 on the last Sunday of March does not exist in Berlin. When they go back, an hour happens twice. The converter tells you when the time you typed is one of these and which moment it shows. Avoid scheduling recurring meetings at those hours.

Midnight and the date line

A time near midnight, or a conversion across the Pacific, often lands on another date. Read the date in each row, not only the time: in January, 11 pm on Monday in Los Angeles is 8 pm on Tuesday in Auckland. The +1 and −1 marks compare each date with the date in the first place.