Time Zone Converter

Converting a time in three simple steps

You do not need to know anything about time zones to use the tool above. If you can say where you are and where your friend is, the tool does the rest.

1. Choose where you are starting from. It is filled in from your device, and the line under the heading tells you what it found. Use the From button to change it.
2. Pick the date and the time. The date matters, because the gap between two places can be different in March than in July.
3. Add the places to compare. Type a city, a country or an abbreviation such as EST. A small badge such as +1 day or −1 day appears when the calendar date is different over there.

The world clock, meeting planner and daylight saving helper are for the moments when one answer is not enough. The rest of this guide explains why the answers look the way they do.

What a time zone actually is

The sun is not overhead everywhere at once. When it is midday in London, people in New York are thinking about breakfast and people in Los Angeles are asleep. If every town kept its own solar time, a train ride of a few hundred kilometres would need a watch you reset at every station. A time zone is the compromise: a whole region agrees to use one clock.

Each zone is described by how far its clock sits from a shared reference. London in winter sits on the reference itself, written UTC+0. New York in winter is five hours behind it, written UTC−5. To get the gap, subtract one offset from the other: 0 minus (−5) is 5 hours. London is further ahead, so its clock shows the later time.

The tool uses names such as Asia/Tokyo and America/New_York, taken from the IANA time zone database that browsers and phones share. A place name is better than a bare number because Asia/Tokyo has one rule all year, while America/New_York switches between two offsets. Using the place keeps the answer right on any date you pick.

UTC and GMT: close cousins, not twins

GMT, Greenwich Mean Time, began as time kept by the sun at the observatory in Greenwich, London. It is also the name of a zone, the one the UK uses in winter and a few countries such as Iceland and Ghana use all year. UTC, Coordinated Universal Time, is the modern standard. It is kept by atomic clocks and occasionally nudged by a leap second to stay in step with the Earth. The last leap second was added at the end of 2016.

A time given in UTC cannot be misunderstood, because UTC never changes for daylight saving. A time given in GMT needs a second look: in summer the UK clocks say British Summer Time, one hour ahead of GMT. For international teams, a good habit is to write the time with a city name, such as “10:00 Colombo time”. The Copy result button does this for you.

Daylight saving time, without the confusion

In many countries the clocks move forward an hour for the lighter months and back again later. It does not add any daylight. It just relabels the hours. Two things make it tricky. Not every country does it: India does not, and neither do Japan, Singapore or the United Arab Emirates. And the countries that do it change on different dates. Seasons in the southern half of the world are the reverse of the north, so Sydney’s summer clock is running while New York is on its winter one. The gap between two places is therefore not a fixed number.

Take 2026, using dates the tool computes from your browser’s database. New York moves its clocks forward on 8 March and back on 1 November. London moves forward on 29 March and back on 25 October. Between 8 and 29 March, New York is on summer time and London is not, so the gap is four hours instead of five. The same happens between 25 October and 1 November. These weeks cause many “I was an hour early” stories, so always pick the actual date rather than doing the sum from memory.

Some places sit out of all this, which is a small gift. When the gap between Tokyo and New York shrinks from 14 hours to 13 hours, it is New York that moved.

Governments set these rules and sometimes revise them. The tool does not guess about the future. It reads the rules your browser currently knows, so after a short-notice change your browser needs an update first. For something that matters, such as a visa interview or a flight, check the official announcement too.

On the change day itself, strange things happen. In spring an hour of local time does not exist: 2:30 AM never appears on a New York clock on the morning of the March change. In autumn an hour repeats, so 1:30 AM happens twice. If you type one of those times above, the tool explains in plain words and, for the repeated hour, lets you choose which one you meant.

A worked example: Sydney to London, in both seasons

Let us do the sum by hand once. Mia in Sydney wants to call her cousin Leo in London. She plans it for 9:00 AM her time on Wednesday 14 October 2026.

Sydney on summer time, London still on summer time (October)

1. On 14 October 2026 Sydney is on daylight saving time, UTC+11. It began on 4 October.
2. London is still on British Summer Time, UTC+1. The UK clocks go back on 25 October.
3. The gap is 11 minus 1, which is 10 hours, with Sydney ahead.
4. Take 10 hours from 9:00 AM Wednesday. Nine hours back reaches midnight, and the last hour lands on 11:00 PM Tuesday.

So 9:00 AM Wednesday 14 October in Sydney is 11:00 PM Tuesday 13 October in London. Leo is about to go to bed. The tool shows a −1 day badge, the clue that the date differs.

London on winter time (January)

1. Sydney is still on UTC+11, because its summer runs from October to April.
2. On 13 January 2027 London is on standard time, UTC+0.
3. The gap is 11 minus 0, which is 11 hours.
4. Take 11 hours from 9:00 AM Wednesday: nine hours back is midnight, and 2 hours more is 10:00 PM Tuesday.

So 9:00 AM Wednesday 13 January in Sydney is 10:00 PM Tuesday 12 January in London. The call moved an hour earlier in the evening there purely because of London’s season.

A quick check goes through UTC. Sydney 9:00 AM is 10:00 PM UTC the day before. Add 1 hour for 11:00 PM in London, or nothing for 10:00 PM. Both routes agree.

Half hours, quarter hours and the date line

Many zones are not whole hours apart. India uses UTC+5:30. Nepal uses UTC+5:45, so Kathmandu is 15 minutes ahead of New Delhi. Adelaide and Darwin sit at UTC+9:30 in standard time, Newfoundland at UTC−3:30, and the Chatham Islands of New Zealand at UTC+12:45. A tool that only handled whole hours would be wrong for well over a billion people, so this one works in minutes.

Then there is the International Date Line, the zigzag in the Pacific where the calendar date changes. At one moment it can be Monday on one side and Tuesday on the other. The earliest clock in the world is UTC+14 on the Line Islands of Kiribati, and the latest is UTC−12 on Baker Island. That is a 26 hour spread, which is why the UTC offset ruler in the tool runs from −12 to +14.

Whenever you cross a big gap, look at the date as well as the hour. A flight from Auckland to the US west coast can land, by the clock, before it took off. That is why every result shows the full weekday and date.

Standard offsets of popular places

Every zone is an offset from UTC. The table lists standard time for places people often convert between, and the summer time offset where the place uses one. Subtract one row’s offset from another to get the gap, and remember that the date you choose decides which column applies.

If a place is missing, add it to the Quick Converter.

Abbreviations that look the same but are not

Three-letter abbreviations are handy in a message and a trap in a contract. They are not official standards, and many mean more than one thing. That is why the search box asks you to choose when you type an unclear one.

IST usually means India Standard Time, UTC+5:30. It can also mean Irish Standard Time, the summer clock in Ireland at UTC+1, or Israel Standard Time, UTC+2 in winter. CST can mean US Central Standard Time (UTC−6), China Standard Time (UTC+8) or Cuba Standard Time (UTC−5). BST is British Summer Time (UTC+1), but also Bangladesh Standard Time (UTC+6). People often write EST all year even when the clock shows EDT. If you are the sender, write a city or the UTC offset.

To convert IST to EST, first decide which IST you mean. For India, the gap to New York is 10 hours 30 minutes in standard time and 9 hours 30 minutes when New York is on EDT. You can also type an offset such as +5:30 in the search box to see which places match on your chosen date.

Meeting etiquette across time zones

Doing the sum right is half of it. The other half is being fair about who gets the awkward hour. Take turns, and say so: “this one is early for me, the next is early for you” avoids the quiet resentment that builds when one city always attends at 10 PM.

The meeting planner shows the whole day for each city. Green is working hours, amber is awake but outside work, and grey is sleep. It highlights the stretch where everyone is at work. If there is none, it offers the least-bad option and explains who bears the cost.

Some pairs overlap well and some do not. London and Dubai share most of a working day, London and New York share a few afternoon hours, and New York and Sydney hardly meet at all, which is why those calls usually fall in someone’s evening or early morning.

A few habits help. Offer two or three options. Put the date and the city in the invite, because “Thursday 8 PM” hides whose 8 PM. Take extra care when a call falls near a clock change.

Tips for travellers, remote workers and students

Travellers: boarding passes use local times at each end, so a flight that leaves London at 11 AM and lands in New York at 2 PM is not 3 hours long. Convert both to one place and subtract. Also check the arrival date, because hotel bookings and visa forms care about it.

Remote workers: share a link instead of a number. The Share link button puts your cities, date, time and working hours into the address. For a recurring call, download the .ics file. It stores the moment in UTC, and calendar apps show each person their own local time, so the invite moves correctly when someone’s clocks change.

Students: online exams and interviews are often announced in the organiser’s time, such as London or Sydney. Convert the date as well as the hour, and add a buffer if the exam falls near a clock change. If the notice only gives an abbreviation, find out which one it means.

Common mistakes, and how to avoid them

The first is using today’s gap for a date months away. London to Sydney is 11 hours in January but 9 hours in July, so a call booked from memory can be two hours out. Set the date you actually mean.

The second is forgetting the calendar. When a result carries a +1 day or −1 day badge, the weekday has changed. “See you Friday morning” from Sydney may be Thursday evening in London.

The third is trusting an abbreviation. If you are not sure what it means, ask. A short question costs less than a missed interview.

The fourth is assuming every country changes clocks on the same weekend. They do not, and some never do. The daylight saving helper shows the dates for your cities.

The last is counting 24 hours forward on a change day. That day can be 23 or 25 hours long, so the clock lands an hour off.