World Clock
Live time for 20 major cities with business-hour indicators, UTC offsets, and local dates — all ticking in sync.
| City | Country | Time | Date | Offset | Status |
|---|---|---|---|---|---|
| New York | US | 03:58:03 | Sat, May 9 | UTC-4 | Off Hours |
| London | UK | 08:58:03 | Sat, May 9 | UTC+1 | Off Hours |
| Tokyo | JP | 16:58:03 | Sat, May 9 | UTC+9 | Off Hours |
| Dubai | AE | 11:58:03 | Sat, May 9 | UTC+4 | Off Hours |
| Singapore | SG | 15:58:03 | Sat, May 9 | UTC+8 | Off Hours |
| Sydney | AU | 17:58:03 | Sat, May 9 | UTC+10 | Off Hours |
| Paris | FR | 09:58:03 | Sat, May 9 | UTC+2 | Off Hours |
| Berlin | DE | 09:58:03 | Sat, May 9 | UTC+2 | Off Hours |
| Hong Kong | HK | 15:58:03 | Sat, May 9 | UTC+8 | Off Hours |
| Mumbai | IN | 13:28:03 | Sat, May 9 | UTC+5:30 | Off Hours |
| Shanghai | CN | 15:58:03 | Sat, May 9 | UTC+8 | Off Hours |
| Los Angeles | US | 00:58:03 | Sat, May 9 | UTC-7 | Off Hours |
| Chicago | US | 02:58:03 | Sat, May 9 | UTC-5 | Off Hours |
| Denver | US | 01:58:03 | Sat, May 9 | UTC-6 | Off Hours |
| Sao Paulo | BR | 04:58:03 | Sat, May 9 | UTC-3 | Off Hours |
| Moscow | RU | 10:58:03 | Sat, May 9 | UTC+3 | Off Hours |
| Seoul | KR | 16:58:03 | Sat, May 9 | UTC+9 | Off Hours |
| Bangkok | TH | 14:58:03 | Sat, May 9 | UTC+7 | Off Hours |
| Istanbul | TR | 10:58:03 | Sat, May 9 | UTC+3 | Off Hours |
| Auckland | NZ | 19:58:03 | Sat, May 9 | UTC+12 | Off Hours |
Understanding the World Clock
A world clock displays the current time in multiple cities simultaneously, letting you compare local times across the globe at a glance. The concept is rooted in the way time zones divide the Earth into longitudinal bands, each offset from Coordinated Universal Time (UTC) by a fixed number of hours and, in some cases, half-hours or even quarter-hours. Because the Earth rotates 360 degrees every 24 hours, each 15-degree slice of longitude corresponds roughly to one hour of time difference. In practice, however, political boundaries, economic ties, and historical convention mean that time zone borders rarely follow neat meridian lines. Countries choose offsets that suit their geography and trade relationships, which is why a single continent can span a dozen or more distinct time zones.
The world clock on this page tracks 20 cities spread across North America, South America, Europe, the Middle East, South Asia, East Asia, Southeast Asia, and Oceania. Each city card and table row updates every second using your browser's built-in clock and the IANA timezone database. No server-side requests are involved; all conversion from UTC to local time happens entirely on your device. The green and gray business-hour indicators give you an instant visual signal of whether colleagues, clients, or markets in a given city are likely to be active right now, making the tool especially useful for scheduling international calls, coordinating remote teams, or monitoring global financial markets.
Major Time Zones
The world's most referenced time zones include Eastern Standard Time (EST, UTC-5), used by New York and much of the US East Coast; Greenwich Mean Time (GMT, UTC+0), the baseline time observed in London during winter months; Central European Time (CET, UTC+1), covering Paris, Berlin, and most of Western Europe; Gulf Standard Time (GST, UTC+4), used by Dubai and the United Arab Emirates; India Standard Time (IST, UTC+5:30), a single zone for the entire Indian subcontinent; China Standard Time (CST, UTC+8), applied uniformly across all of China despite the country spanning five geographical time zones; Japan Standard Time (JST, UTC+9), which Tokyo and all of Japan observe year-round without DST; and New Zealand Standard Time (NZST, UTC+12), one of the first zones to greet each new calendar day.
Several time zones use fractional offsets that complicate simple hour-based arithmetic. India's UTC+5:30 and Nepal's UTC+5:45 are the most well-known examples, but Iran (UTC+3:30), Afghanistan (UTC+4:30), Myanmar (UTC+6:30), and the Chatham Islands of New Zealand (UTC+12:45) also use non-integer offsets. When scheduling across these zones, it is important to rely on IANA timezone identifiers rather than manually adding or subtracting hours, because the fractional offsets and DST rules make mental math unreliable.
Daylight Saving Time Around the World
Daylight Saving Time (DST) is the practice of advancing clocks by one hour during warmer months to extend evening daylight. Approximately 70 countries observe DST, with the practice most common in North America and Europe. In the United States and Canada, DST begins on the second Sunday of March and ends on the first Sunday of November. The European Union follows a different schedule, starting DST on the last Sunday of March and ending on the last Sunday of October. Southern Hemisphere countries that observe DST, such as Australia and New Zealand, shift their clocks during the opposite part of the year, typically from October to March or April.
Many countries and regions do not observe DST at all. Japan has not used DST since 1951. China abolished it in 1991. India, South Korea, Singapore, Thailand, and the majority of Africa and South America remain on fixed offsets year-round. Even within countries that observe DST, exceptions exist: Arizona (excluding the Navajo Nation) and Hawaii do not participate in the United States, and Queensland opts out in Australia. Russia experimented with permanent summer time in 2011 before switching to permanent winter time in 2014. The European Union voted in 2019 to end mandatory clock changes, though member states have not yet agreed on a final implementation date. These variations mean the UTC offset between any two cities can change several times per year, reinforcing the importance of using IANA timezone identifiers in software rather than hardcoded numeric offsets.
The IANA Timezone Database
The IANA Time Zone Database, commonly called the tz database or Olson database after its original creator Arthur David Olson, is the authoritative reference for timezone rules used by virtually every operating system, programming language, web browser, and smartphone on the planet. Each entry in the database is identified by a Region/City string such as "America/New_York" or "Asia/Tokyo," chosen to be geographically unambiguous and stable over time. The database records not only current UTC offsets and DST rules but the complete historical timeline of timezone legislation for every region, stretching back to the adoption of standard time in the late 19th century.
The database is maintained by a volunteer community coordinated through the IANA (Internet Assigned Numbers Authority) and receives several updates per year as countries revise their timezone laws. Recent updates have addressed changes in Morocco, Palestine, Fiji, and other regions that frequently adjust DST schedules. When your browser converts a UTC timestamp to local time, it consults a copy of this database that ships with your operating system or browser engine. This is why keeping your OS and browser up to date is important for accurate time display, especially in regions where governments announce DST changes on short notice. The world clock on this page relies entirely on your browser's copy of the tz database, ensuring that displayed times reflect the most current rules your device knows about.
Frequently Asked Questions
How does the world clock determine my local time?
The world clock reads your timezone from your operating system through the browser's Internationalization API. It calls Intl.DateTimeFormat().resolvedOptions().timeZone to retrieve your IANA timezone identifier, then uses the timezone database bundled with your browser to convert UTC to your local time. No server request, GPS lookup, or IP geolocation is involved. All calculations happen entirely on your device.
What do the green and gray dots mean?
A green dot indicates that the city is currently within standard business hours: Monday through Friday, 9:00 AM to 5:00 PM local time. A gray dot means the city is outside business hours, either because it is a weekend or because the local time falls outside the 9-to-5 window. This is useful for quickly identifying which cities have active offices or open financial markets.
Why do some cities share the same UTC offset but show different times during part of the year?
Daylight Saving Time shifts the UTC offset of participating regions by one hour during warmer months. For example, New York is UTC-5 in winter but UTC-4 in summer, while Panama remains UTC-5 year-round. Two cities at the same longitude can therefore differ by an hour for several months each year. The IANA timezone database tracks these transitions so the world clock always displays the correct local time.
How many time zones does the IANA database track?
The IANA Time Zone Database tracks over 400 named timezone regions. These represent not just the 38 distinct UTC offsets currently in use but also historical timezone configurations that have changed over time due to political decisions, border changes, and evolving DST legislation. The database is updated several times per year to reflect new laws and amendments.
Which countries do not observe Daylight Saving Time?
Most countries near the equator do not observe DST because the variation in daylight hours throughout the year is minimal. Notable examples include Japan (since 1951), China (since 1991), India, South Korea, Singapore, Thailand, Indonesia, and the majority of nations in Africa and South America. In the United States, Arizona (excluding the Navajo Nation) and Hawaii do not participate. In Australia, Queensland and the Northern Territory opt out.