World Time Zone Converter

How this converter works

The converter treats your input as a wall-clock time in the "from" city, turns it into one exact instant in UTC (Coordinated Universal Time), and then asks what the wall clock reads in the "to" city at that same instant. Every city on the list is tied to an IANA time zone identifier such as America/New_York or Asia/Kolkata. The browser's built-in Intl.DateTimeFormat API, which uses the IANA time zone database, reports the UTC offset that applies in that zone on the date you chose. Because the offset comes from the date, the tool does not just add or subtract a fixed number of hours: it knows when a city is on daylight saving time and when it is not.

The list has 25 cities, chosen to cover the main business regions: East and South Asia, the Middle East, Europe, South America, North America (including Alaska and Hawaii) and Australasia. It is a convenient sample rather than a full atlas. If your city is missing, pick one that shares its time zone. Washington, D.C. follows the same clock as New York, and Vancouver follows Los Angeles.

Limits. The result depends on the time zone data inside your browser or operating system. If a country changed its rules recently and your device has not been updated, the result may still follow the old rule. Dates in the far future are calculated on the assumption that today's rules continue, and governments do change them. For travel bookings, contracts, deadlines and exams, confirm the local time with the organization that issues the document.

UTC, offsets and why time zones exist

The Earth turns 360 degrees in about 24 hours, so local solar time shifts by roughly one hour for every 15 degrees of longitude. To avoid every town keeping its own clock, the world adopted standard time zones, which are normally defined as an offset from UTC. UTC replaced the older astronomical reference, Greenwich Mean Time, as the basis of civil time; in everyday use the two are treated as the same value, although the United Kingdom uses GMT in winter and British Summer Time (UTC+1) in summer. An offset of UTC-5 means the local clock is five hours behind UTC, and UTC+9 means nine hours ahead. Offsets in use range from UTC-12 to UTC+14.

Not every offset is a whole number of hours. In this list, the cities with a fractional offset are: New Delhi (UTC+5:30). Elsewhere in the world, Nepal uses UTC+5:45. The converter works in minutes, so those differences come out correctly: when it is 09:00 in New York in the January example below, it is 19:30 in New Delhi.

UTC offsets for the 25 cities, computed at build time

The table below was produced when this page was built, using the time zone data available to the build, so none of the figures were typed by hand. It compares the offset on 15 January and on 15 July of 2026. A city whose two offsets differ observes daylight saving time that year: 12 of the 25 cities do and 13 do not. The last column lists the moments in 2026 at which that city's offset changes, as reported by the time zone data, written as the local date and time just after the change. These are results of a calculation, not an official announcement; official dates can change and should be confirmed with the relevant government.

Daylight saving time differs by region

Daylight saving time (DST) moves the clock forward in the warm season and back again afterwards. There is no single worldwide rule. Most of the United States and Canada use it, and so do the European countries on this list. Because the Southern Hemisphere has summer in December to February, Sydney and Auckland are on daylight time during the Northern Hemisphere winter, so their clocks change in the opposite direction. Many places never use it, including Japan, China, Singapore, India, Thailand, Indonesia and the United Arab Emirates, and Hawaii does not either. Some countries have dropped it or fixed their clocks: for instance, the table shows Moscow, Istanbul and São Paulo with no offset change in 2026.

A practical consequence is that the gap between two cities is not constant. Because the US and Europe usually change their clocks on different weekends, there are short windows in spring and autumn when the New York to London gap is one hour shorter than usual. Check the offset table for the actual changeover moments and use the date field of the converter to test any day you care about.

Worked examples, calculated with the same code as the converter

Example 1: mid-winter, 15 January 2026, 09:00 in New York. That is 2026-01-15 14:00 (UTC+0) in London,2026-01-15 23:00 (UTC+9) in Tokyo, 2026-01-15 19:30 (UTC+5:30) in New Delhi, and 2026-01-16 01:00 (UTC+11) in Sydney. Notice that Sydney is on the next calendar day, and that New Delhi lands on a half hour.

Example 2: mid-summer, 15 July 2026, 09:00 in New York. The local time is now 2026-07-15 14:00 (UTC+1) in London,2026-07-15 22:00 (UTC+9) in Tokyo, 2026-07-15 18:30 (UTC+5:30) in New Delhi and 2026-07-15 23:00 (UTC+10) in Sydney. London moved relative to the winter example because the United Kingdom is on summer time, and Sydney moved because it is on standard time while New York is on daylight time. Tokyo has no daylight saving, so it only changed because New York did.

Example 3: 15 March 2026, 09:00 in New York. In the data this page was built with, that gives 2026-03-15 13:00 (UTC+0) in London, a gap of four hours, against five hours in January. The US and Europe are in different phases at this point in the calendar. If you schedule a call with colleagues at this time of year, test the specific date.

Common mistakes

• Memorizing one fixed difference. "New York is 5 hours behind London" holds for most of the year but not all of it. Always include the date.
• Treating a country as one time zone. The contiguous United States spans four, Russia many more, and Australia and Canada several. Choose the right city: Chicago is Central, Denver is Mountain, Los Angeles is Pacific.
• Assuming a big country has many zones. China uses a single standard time (Beijing time, UTC+8) across the whole country.
• Ignoring the changeover day itself. On the spring day, one local hour does not exist, so a time such as 02:30 in New York on that date is skipped; on the autumn day, one hour happens twice. The converter reports an error for a skipped time, and for a repeated time it calculates only one of the two possibilities, so check the hours around a changeover manually.
• Writing "10 AM" in an invitation with no zone. The recipient may read it in their own zone. Always add the zone name or the UTC offset.

Practical tips for scheduling across zones

Put the time zone in every invitation, and use the calendar app's time zone field so that each guest sees their own local time. For recurring meetings, be careful around the clock changes: a weekly call fixed at 9:00 in New York can shift by an hour in London's calendar for a few weeks each spring and autumn, when the two regions are out of step. For deadlines, "23:59 UTC" is unambiguous and unaffected by daylight saving. In server logs and databases, store timestamps in UTC and convert only when displaying them. When you talk about flights, remember that departure and arrival times are printed in local time, so an overnight flight can arrive on a different date than the one you left on. Entering a date in this converter makes the date change visible.

If you need to count the days to an event rather than convert a clock time, theD-day countdown calculator is a better fit. For a simple list of times in any city, see the Timezone Converter, and for background on why the planet's rotation drives all of this, read Earth science facts.

Frequently Asked Questions