WorldClock is a free, browser-based utility designed to solve one deceptively simple problem: knowing what time it is, somewhere else, right now. Whether you are scheduling a video call with a client in Tokyo, coordinating a family gathering across three continents, or simply curious whether your friend in London is awake, the information you need should be one glance away — not buried behind calculations, mental math, or dated conversion tables.

Every feature on this site is built around that principle. Our main clock shows your local time down to the second, synchronized to your device's own timezone. You can pin up to ten additional city clocks from a curated list of forty-eight major world cities, each displayed at the same generous size so no location feels secondary. The timers and alarms work entirely in your browser — no accounts, no tracking, no data leaves your device — making this a reliable companion for focused work sessions, cooking, workouts, and daily routines.

We built WorldClock because the tools we found online were either cluttered with intrusive features, slow to load, or aesthetically tired. A clock is something you might look at fifty times a day. It deserves to be beautiful.

The Origin of Standard Time

Until the late nineteenth century, every town kept its own clock, set by the position of the sun overhead. Noon in one village might be eleven minutes after noon in the next. This worked fine when people rarely traveled faster than a horse could carry them. It broke completely the moment railways began connecting cities at a speed that made local time a scheduling nightmare.

In 1884, representatives from twenty-five nations met at the International Meridian Conference in Washington, D.C., and agreed to divide the globe into twenty-four time zones, each fifteen degrees of longitude wide, with the prime meridian passing through the Royal Observatory at Greenwich, England. Every zone would be exactly one hour offset from its neighbors. The elegant geometry of this system is why we still talk about GMT and UTC today.

GMT, UTC, and the Difference Between Them

You will encounter two abbreviations constantly when dealing with international time: GMT (Greenwich Mean Time) and UTC (Coordinated Universal Time). For most practical purposes they are identical — both describe the time at the prime meridian with no timezone offset and no daylight-saving adjustment. The technical distinction is that GMT is based on astronomical observation of the sun, while UTC is based on atomic clocks and is therefore far more precise. Since 1972, UTC has been the global civil time standard, and all other time zones are described as an offset from it (for example, UTC+5:30 for India, or UTC−8 for the Pacific coast of North America).

Why Some Offsets Are Not Whole Hours

Most countries chose a whole-hour offset from UTC, but a handful adopted half-hour or even quarter-hour offsets for geographic or political reasons. India uses UTC+5:30, Iran uses UTC+3:30, Newfoundland uses UTC−3:30, and Nepal uses the unusual UTC+5:45. These offsets are not mistakes — they typically reflect the longitude of a central national city and a desire to have clocks that match the sun's actual position.

Daylight Saving Time

Many countries in the temperate latitudes shift their clocks forward by one hour in spring and back again in autumn. This practice, called daylight saving time (DST), aims to make better use of evening daylight during summer months. In practice it means a city's offset from UTC can change twice a year — New York, for example, is UTC−5 in winter but UTC−4 in summer. Our clocks handle these transitions automatically using your browser's timezone database, so you never need to adjust anything manually.

Not every country observes DST. Most of Asia, nearly all of Africa, and much of South America keep the same offset year-round. This can be a source of confusion when scheduling across regions that handle DST differently — what was a six-hour difference in January might become a seven-hour difference in June.

The International Date Line

If you kept moving west around the globe, each new time zone would set you one hour further behind the previous one. After twenty-four zones, you would be an entire day behind — which cannot be right. The International Date Line, running roughly along the 180-degree meridian in the Pacific Ocean, resolves this paradox. Cross it going west, and you skip a day forward. Cross it going east, and you repeat a day. This is why a flight from Los Angeles to Tokyo appears to arrive before it departed, at least on the calendar.

City	UTC Offset	Region	Observes DST
London	UTC+0	United Kingdom	Yes
Paris	UTC+1	Central Europe	Yes
Berlin	UTC+1	Central Europe	Yes
Cairo	UTC+2	North Africa	Yes
Moscow	UTC+3	Eastern Europe	No
Dubai	UTC+4	Middle East	No
Karachi	UTC+5	South Asia	No
Mumbai / Delhi	UTC+5:30	India	No
Colombo	UTC+5:30	Sri Lanka	No
Dhaka	UTC+6	Bangladesh	No
Bangkok	UTC+7	Southeast Asia	No
Singapore	UTC+8	Southeast Asia	No
Beijing / Shanghai	UTC+8	China	No
Hong Kong	UTC+8	Hong Kong	No
Tokyo	UTC+9	Japan	No
Seoul	UTC+9	South Korea	No
Sydney	UTC+10	Australia	Yes
Auckland	UTC+12	New Zealand	Yes
Honolulu	UTC−10	Hawaii	No
Los Angeles	UTC−8	US Pacific	Yes
Denver	UTC−7	US Mountain	Yes
Chicago	UTC−6	US Central	Yes
Mexico City	UTC−6	Mexico	Varies
New York / Toronto	UTC−5	US/Canada East	Yes
São Paulo	UTC−3	Brazil	No

Find an Overlap Window, Not a Meeting Time

When scheduling meetings with someone in a distant time zone, the most common mistake is searching for a time that is convenient for both parties. This rarely exists. Instead, identify the overlap window — the hours where both of you are reasonably awake and working — and protect it as shared collaboration time. A team in San Francisco and one in Berlin have only a narrow three-hour window each day where everyone is comfortably at their desks. Treat that window as precious. Schedule synchronous work (calls, live reviews, pair programming) inside it, and everything else (documentation, research, deep work) outside it.

Default to Asynchronous Communication

If a conversation does not need to happen in real time, it should not happen in real time. Written messages, voice notes, recorded videos, and detailed documents scale across time zones in a way that meetings never will. A well-written async message lets someone in India respond when they wake up, and your colleague in Mexico read the whole thread with fresh coffee. The key discipline is writing as if the reader cannot ask clarifying questions, because in an async world they often cannot — not for hours.

Always Communicate in the Other Person's Time Zone

When you send a message saying "let's meet at 3pm" without specifying the zone, you are creating an ambiguity that will cost someone an hour or a missed call. Better to say "3pm your time" or "3pm Pacific" or simply "15:00 UTC." Even better, include both: "3pm Pacific (that is 6pm your time in New York)." This costs you two seconds and saves the other person a lookup on our site or a mental calculation they will get wrong one time out of five.

Respect the Human on the Other End

Asynchronous does not mean inconsiderate. Avoid scheduling synchronous meetings that fall during the other person's dinner, deep night, or early morning. If it cannot be avoided — and sometimes it cannot — rotate the inconvenience. If you make them wake early this week, you wake early next week. Distributed work can feel frictionless, but the person on the other side is still a human with a sleep schedule, a family, and their own deep-work hours that deserve protection.

Use Timers for Focus, Not Pressure

The Pomodoro technique — twenty-five minutes of focused work followed by a five-minute break — is popular for a reason. It works because it makes the scope of the next block of work small enough to feel achievable, and it enforces breaks that your brain actually needs. Our timers are designed for exactly this: name them, start them, and when they ring, take the break. The discipline is not starting the timer; it is respecting what it tells you when it ends. Start multiple timers for different cooking dishes, workout intervals, or study subjects that need rotating attention.

Set Alarms for Things You Keep Forgetting

If you have ever missed taking medication, forgotten to stretch during a long coding session, or lost track of the time during a creative flow, a repeating alarm is the simplest possible fix. Set one for the thing you keep forgetting, pick the days of the week that are relevant, and let it interrupt you. The brief irritation of the alarm is always less than the consequence of forgetting.