World Timezone Map

Real-time day & night boundary with local times for major cities

Fully browser-based — time comes from your device clock, nothing is sent to a server

UTC ● LIVE

00:0006:0012:0018:0024:00

The day/night boundary is calculated from the Earth's rotation and axial tilt (solar time). City clocks follow political timezone boundaries set by each country, so the two may not align exactly.

Tips

🌍

Real-Time Day & Night

The map calculates the sun's position from your PC clock and draws the day/night boundary in real time. No server calls — works offline too.

⏱️

Live vs Fixed Mode

By default the map runs in LIVE mode, updating every second. Set a specific date/time or use the URL ?time= parameter to freeze at any moment.

📌

City Popups with Local Time

Click a city marker to see its current local time, calculated from UTC + the city's timezone offset. The popup updates in real time during LIVE mode.

🔗

Shareable Time Links

When you set a specific time, the URL updates automatically. Copy and share the URL to show someone the exact same day/night view.

🎮

Time Travel with Play

Use the Play button to animate the day/night boundary moving across the globe. Each step advances one minute, so you can watch a full day pass in seconds.

Common Use Cases

🌐

Schedule International Meetings

Visually check what time it is across multiple cities before scheduling a call or video conference across time zones.

✈️

Plan Travel Timing

See where it will be day or night when you arrive at your destination. Great for planning flights and adjusting to jet lag.

📡

Monitor Global Operations

DevOps and support teams can see at a glance which offices or data centers are in business hours versus overnight.

📚

Educational Visualization

Demonstrate how Earth's rotation and axial tilt create seasons and varying day lengths. Perfect for geography or astronomy classes.

Frequently Asked Questions

Where does the time come from?

The time is read from your device's system clock using JavaScript. No external time servers or APIs are contacted. If your PC clock is off, the map will reflect that offset.

How accurate is the day/night boundary?

The boundary uses a simplified solar position model based on the solar declination formula. It is accurate enough for general visualization but does not account for atmospheric refraction, the equation of time, or terrain elevation.

What does the ?time= URL parameter do?

Adding ?time=2026-04-01T15:30Z to the URL loads the map at that specific UTC moment in fixed mode. Omitting it or using ?time=now starts in live mode with your current time.

Can I use this offline?

Once the page and its static files are cached by your browser, the map works entirely offline. All calculations happen in JavaScript with no server dependency.

Why do some cities show unexpected times?

Each city uses a fixed UTC offset. Daylight saving time (DST) changes are not automatically applied. The displayed offset reflects standard time for that timezone.

What map projection is used?

The map uses the Natural Earth projection, a pseudo-cylindrical projection designed for world maps. It provides a good balance between shape and area distortion.