World Clock
Current local time in cities around the world
No cities match your search.
How does a world clock work?
The world is divided into time zones based on longitude. Each zone is roughly 15 degrees wide, representing one hour of difference from its neighbour. As the Earth rotates, the sun appears to move across the sky at different times in different places — noon in London is still night in New York. Time zones let every region set its clocks to match local solar time.
UTC (Coordinated Universal Time) is the global standard that all time zones are offset from. It replaced GMT as the international reference in 1972 and is kept precise using atomic clocks. Every city on a world clock is expressed as UTC plus or minus a number of hours — for example, New York is UTC−5 and Tokyo is UTC+9.
Clockr uses the browser's built-in Intl.DateTimeFormat API with IANA timezone identifiers to display accurate local times for every city. Each city card is linked to a named timezone like "America/New_York" or "Asia/Tokyo", and the API handles daylight saving changes, half-hour offsets, and historical adjustments automatically — updating every second without any server round-trip.
Frequently asked questions
How many time zones are there in the world?
There are 24 primary longitudinal time zones, one for each hour of the day. In practice, however, there are around 38 different UTC offsets in use worldwide because countries adopt zones that don't align neatly with 15-degree segments. Some nations use half-hour or quarter-hour offsets, and daylight saving time adds further variation throughout the year.
What is UTC and how does it work?
UTC (Coordinated Universal Time) is the world's primary time standard. It is based on atomic clocks and is accurate to within a fraction of a second. All time zones are defined as an offset from UTC — for example, UTC+1 is one hour ahead and UTC−8 is eight hours behind. UTC occasionally adds a leap second to stay aligned with Earth's rotation, though leap seconds are being phased out.
Which country has the most time zones?
France holds the record with 12 or 13 time zones, depending on how overseas territories are counted — including locations in the Pacific, Indian Ocean, and South America. Russia spans 11 time zones across its vast territory, and the United States covers 11 when including territories like Guam and American Samoa.
What is the International Date Line?
The International Date Line is an imaginary boundary running roughly along the 180° meridian in the Pacific Ocean. Crossing it eastward moves the calendar back one day; crossing westward moves it forward one day. It exists so that neighbouring regions on opposite sides of the globe don't share the same date while being 24 hours apart in local time. The line zigzags around island nations to keep entire countries on the same calendar day.
Why do some countries have half-hour time zones?
Half-hour and quarter-hour offsets exist because political and geographic boundaries don't always align with neat 15-degree longitude segments. India uses UTC+5:30 so that the entire country shares one time zone despite spanning nearly 30 degrees of longitude. Nepal uses UTC+5:45, and Australia's Lord Howe Island uses UTC+10:30 in summer and UTC+11 in winter. These offsets reflect practical decisions about national unity and local solar time.
What is daylight saving time and which countries use it?
Daylight saving time (DST) shifts clocks forward by one hour in spring and back in autumn to make better use of evening daylight. It is used in parts of North America, Europe, Australia, and a handful of other regions — but not uniformly. Many countries, including Japan, India, and most of Africa, do not observe DST at all. Clockr automatically reflects DST changes through IANA timezone data, so city times stay accurate year-round.
What is the biggest time difference between two places on Earth?
The maximum offset between two inhabited places is 26 hours. Howland and Baker Islands in the Pacific (UTC−12) are a full day behind Kiritimati in Kiribati (UTC+14) — so when it is noon on Monday in Kiritimati, it is still 10:00 on Sunday in Howland Island. Even between major cities, the gap can be 20 hours or more, such as between Honolulu and Auckland.
What time zone is GMT and is it the same as UTC?
GMT (Greenwich Mean Time) is the time zone centred on the Royal Observatory in Greenwich, London. For almost all practical purposes, GMT and UTC are identical — both are at offset zero. Technically, GMT is based on Earth's rotation while UTC is based on atomic clocks, but the difference is less than a second. In winter, the UK uses GMT; in summer it switches to BST (British Summer Time, UTC+1).