World Clock

The World Clock shows the current local time in cities all over the planet, side by side, and updates every second. Unlike a plain list of times, every city carries a real day-and-night indicator worked out from the sun's actual position in the sky, so you can tell at a glance who is in bright daylight, who is in the soft light of dawn or dusk, and who is fast asleep in the middle of the night. Add the cities you care about, see how far ahead or behind each one is, and use the built-in meeting planner to find an hour that works for everybody.

What Makes This World Clock Different

How the Day and Night Indicator Works

For each city the tool calculates the elevation of the sun above the horizon right now, using the city's latitude and longitude together with the current date and time. The sky is then classified the way astronomers do it:

• ☀️ Daytime — the sun is above the horizon (elevation greater than 0°).
• 🌅 Dawn / 🌆 Dusk — civil twilight, when the sun sits between the horizon and 6° below it. The tool checks whether the sun is rising or setting to label it dawn or dusk.
• 🌙 Night — the sun is more than 6° below the horizon and it is genuinely dark.

Because this uses real solar geometry, a northern city in summer correctly shows daylight late into the evening, while the same city in winter goes dark in the afternoon — something a fixed-hours clock can never get right.

How to Use the Meeting Planner

Scheduling across time zones is the hardest part of remote work, so the planner is built to make it obvious:

1. Each row is one of your cities; each column is one hour of your local day.
2. Every cell is shaded by that city's day or night at that moment, and a green underline marks standard working hours of 9am to 6pm in that city.
3. Tap any column to select a candidate time. The banner above tells you whether that instant falls inside working hours for everyone, and lists the exact local time in each city.
4. The column outlined in amber is the current moment, so you always know where "now" is on the grid.

Understanding Time Zones, UTC and DST

A time zone is a region that keeps the same standard time, usually expressed as an offset from UTC (Coordinated Universal Time), the world's reference clock. London is near UTC, New York is roughly five hours behind, and Tokyo is nine hours ahead. Daylight saving time (DST) nudges many regions' clocks forward by an hour in their summer, which is why the gap between two cities can change a few times a year — and why two places that are normally one hour apart can briefly be the same or two hours apart while one has switched and the other has not.

World Time Zone Reference (Standard Time)

The live clocks above always follow current daylight-saving rules. The table below lists approximate standard-time offsets from UTC for popular cities as a quick reference.

How to Use This Tool

1. Add your cities: Type a city name in the search box or tap a popular city chip.
2. Read the live clocks: Each card shows the local time, date, time difference from you, and a sun-based day/night badge.
3. Plan a meeting: Use the planner grid to pick an hour that lands in working hours across all your cities.
4. Save or share: Copy the share link or bookmark the page to keep your board.

Frequently Asked Questions

How does the world clock know the correct time for each city?

The clock reads your device's clock and converts it to each city's local time using your browser's built-in IANA time-zone database. That database tracks daylight saving time and historical rule changes, so the displayed times follow each region's current rules automatically without any server lookup.

How is the day and night indicator calculated?

For each city the tool computes the sun's elevation above the horizon from the city's latitude and longitude and the current moment. When the sun is above the horizon it is daytime; from zero down to six degrees below the horizon it is civil twilight, shown as dawn or dusk; below that it is night. This is far more accurate than simply assuming day runs from 6am to 6pm.

What is the meeting planner for?

The meeting planner lays every city on one shared timeline. A single column represents one instant in time, and each city's row shows what its local clock reads at that instant, shaded for daytime and standard working hours of 9am to 6pm. Pick a column to instantly see a candidate meeting time that works across all of your cities.

Does daylight saving time change the results?

Yes. Because the tool uses the browser time-zone database, cities that are currently observing daylight saving time show their shifted local time, and the time difference versus your location updates accordingly. Time differences between regions can change a few times a year as different countries enter or leave DST on different dates.

Are my cities saved?

Your selected cities are stored locally in your browser and encoded in the page URL. Reopen the page and your board returns; copy the link to share the exact same board with someone else. Nothing is sent to a server and no account is required.

What is UTC and why is it in the list?

UTC, Coordinated Universal Time, is the global reference time that does not observe daylight saving. It is widely used in aviation, computing, science and international coordination. Adding the UTC card gives you a fixed anchor to compare every other city against.

Additional Resources

• Time Zone - Wikipedia
• Coordinated Universal Time - Wikipedia