World Clock

World Clock & Meeting Time Planner for Global Teams

A world clock and meeting time planner that displays the current time in multiple cities side by side, with UTC offsets and accurate time differences shown in hours and minutes (including half- and quarter-hour zones). The built-in Meeting Time Planner shades each city's business hours on a 24-hour timeline and highlights the overlapping working-hours window, so you can schedule international calls without waking anyone at 3am. Everything runs in your browser and respects each region's daylight-saving rules automatically.

What time is it in Tokyo, London, or New York right now?

Add any of those cities to the world clock and you will see the local wall-clock time updated every second from your own machine's clock. Tokyo is UTC+9 year-round (no DST), London is UTC+0 in winter and UTC+1 in British Summer Time, and New York is UTC-5 in winter and UTC-4 during Eastern Daylight Time. Because this tool reads time from your device and then offsets it using the IANA time-zone database, the displayed value matches the official civil time published by each country's metrology institute as long as your own system clock is correct. If you see a mismatch of an hour, your operating system probably has the wrong DST rules and needs an OS update so the tzdata package is current.

How do I find a meeting time that works for everyone across 3+ time zones?

Add every participant's city, then open the Meeting Time Planner below the clocks. Set the date you want to schedule and each side's business hours (default 09:00–18:00), and the planner shades every city's local working window on a 24-hour strip and highlights the green overlap band — the span where it is daytime for all cities at once. Drag the slider to any moment and the readout shows the exact local clock time in every city simultaneously, so you can pick a slot like 'New York 09:30, London 14:30, Tokyo 22:30' without doing mental arithmetic. Because the planner derives every offset live from the IANA database via the browser's Intl API, it automatically respects each region's daylight-saving rules for the chosen date — so a recurring meeting you plan today will still land in business hours after a DST change. When no green band appears it means the zones share no common working hours; widen one side's business hours, or accept that one participant must take an early or late call. To share the result, just tell each person their own local time from the readout — that survives time-zone confusion better than sending a single absolute time.

How do I add a new city to my world clock list?

Pick the city from the searchable selector, or type the IANA zone name directly such as Europe/Paris, America/Argentina/Buenos_Aires, or Pacific/Auckland. The tool stores your list in browser local storage so it persists across reloads and works offline. You can give any clock a custom label, remove it with the close icon, and the time is shown in clear 24-hour digital format. The IANA database includes more than 350 named zones covering every populated region of Earth, so even small islands such as Niue, Pitcairn, or Norfolk Island are represented with their own offsets. Some countries such as India and China use a single zone despite spanning a wide longitude range.

Can I save my favorite cities so they come back next visit?

Yes — the world clock writes your list of cities to localStorage under a single key, so the same set reappears whenever you open the page in the same browser profile. Clearing site data, switching browsers, or opening in a private window will reset to the defaults. If you want the same list on a phone and a laptop, simply note down the IANA zone names (such as Europe/Paris or Asia/Tokyo) and re-add them on the other device. Local storage holds roughly 5 MB per origin, far more than needed for hundreds of cities, so there is no practical limit on how many clocks you can pin.

What is the difference between UTC and GMT, and which should I use?

Greenwich Mean Time was defined by the Royal Observatory in the 19th century from astronomical observation of the Sun crossing the meridian. Coordinated Universal Time was introduced in 1972 and is maintained by atomic clocks at the BIPM in Sèvres, France. The two are kept within 0.9 seconds of each other through leap-second insertions, so for civil purposes they are interchangeable, and Britain even uses GMT as its winter zone name. For technical work — APIs, logs, aviation, finance — always specify UTC, because GMT is officially a time zone (the UK's winter offset) while UTC is the universal time standard. The CGPM resolved in 2022 to phase out leap seconds by 2035, after which UT1 and UTC will drift slowly apart.

Why does daylight saving time exist and which countries still use it?

Daylight saving time was proposed by George Hudson in New Zealand in 1895 and first implemented nationally by Germany in 1916 to conserve coal during World War I. The idea is to shift waking hours into the longer evening daylight of summer, saving artificial lighting. Modern studies are mixed: small electricity savings exist in some climates but are offset by increased cooling and morning heating loads. About 70 countries still observe DST, mostly in Europe, North America, parts of Australia, and a few in South America. China, India, Japan, most of Africa, and large parts of Asia never use it. Mexico abolished DST nationwide in 2022, and the EU has been debating abolition since 2018 without final action.

Why does Nepal use UTC+5:45 and India use UTC+5:30 — what are the strangest offsets?

Most countries use whole-hour offsets from UTC, but a handful use half-hour or quarter-hour offsets to better align local noon with solar noon. Nepal Standard Time is UTC+5:45, chosen so Nepali time would be exactly 15 minutes ahead of Indian Standard Time at UTC+5:30. The Chatham Islands in New Zealand use UTC+12:45 (and +13:45 in DST), the most outlying quarter-hour offset on Earth. Iran, Afghanistan, Myanmar, Sri Lanka, and parts of Australia also use half-hour offsets. At the extremes, Kiribati's Line Islands use UTC+14, the world's earliest zone, while American Samoa uses UTC-11. Kiribati moved the date line east in 1995 so its territory would share a single calendar day.

How accurate is the time shown — is it synced to atomic clocks?

The world clock reads time from your device via JavaScript's Date object, which itself is set by the operating system. On modern OSes the system clock is disciplined by NTP (Network Time Protocol), typically against pool.ntp.org or vendor-run servers like time.apple.com or time.windows.com. NTP keeps a desktop within 10–100 milliseconds of UTC under normal network conditions; PTP (Precision Time Protocol, IEEE 1588) reaches sub-microsecond on local Ethernet. The world's reference is TAI (International Atomic Time) maintained by about 400 cesium and hydrogen-maser clocks worldwide, coordinated by the BIPM. UTC is TAI minus leap seconds, currently TAI − 37 seconds as of 2026. For sub-millisecond accuracy in the browser use performance.now(), not Date.now().

How does the IANA time-zone database handle historical and political changes?

The IANA (formerly Olson) tz database is the canonical source for civil time worldwide and is updated roughly every six months as governments change their rules. Each zone such as America/New_York stores the full history of UTC offsets and DST transitions back to roughly 1970, with some entries going further. Zones are named after the largest city in a region rather than country, so political renaming does not break records — Asia/Saigon was renamed to Asia/Ho_Chi_Minh, Europe/Kiev to Europe/Kyiv. When a country changes DST policy, the IANA maintainers issue a new tzdata release (such as 2026a, 2026b) that operating systems and browsers must pull in. Bundled Java runtimes, container base images, and air-gapped systems are common sources of stale zone data.

Key Features

• Display current time in multiple timezones simultaneously
• Meeting Time Planner with working-hours overlap finder
• Accurate time differences in hours and minutes (half/quarter-hour zones)
• Real-time clock updates every second
• Add/remove timezones easily
• Search timezones by city or name
• Popular timezones quick access
• View UTC offset for each timezone
• See time difference from your local time
• Date display (shows different days)
• Automatic DST (Daylight Saving Time) handling
• Fullscreen mode for better viewing
• Clear all timezones at once
• Responsive mobile-friendly design
• Dark mode support
• Bookmark-friendly (saves your setup)
• No data sent to server
• 100% client-side
• Fast and accurate
• Works offline
• Timezone abbreviations shown
• Perfect for remote teams