How are time zones determined?

Each zone is defined by its UTC offset. Eastern Time runs at UTC minus 5 (and minus 4 during DST), Tokyo sits at UTC plus 9 with no DST, and London bounces between UTC and UTC plus 1 across the year. The world clock leans on your operating system's IANA Time Zone Database for those offsets, which means historical and current rules are both handled automatically.

What about Daylight Saving Time?

Most of North America, Europe, and Australia observes DST and shifts by an hour during summer. Hawaii, most of Arizona, and almost all of Asia stay put year-round. The clock applies DST automatically based on the date, but it's worth verifying if your specific location has unusual local rules — Indiana counties, for example, used to be famously inconsistent.

How accurate is the displayed time?

Accuracy mirrors your computer's clock. On a connected machine that's typically within a second of UTC thanks to NTP. For mission-critical work — trading systems, scientific timing — you'd want a dedicated NTP-disciplined clock; for everyday scheduling, the system clock plus the browser's time zone awareness is more than enough.

Can I add custom cities?

Yes. Most clocks let you search for any city or time zone in the IANA database, which is handy when the default list doesn't include the location you actually need. The better tools also handle the unusual offsets — India at UTC plus 5:30, Iran at plus 3:30, Nepal at plus 5:45 — without complaining.

What's the difference between time zones and offsets?

Time zones are named regions like America/New_York or Asia/Tokyo and they automatically handle DST and historical rule changes. Raw offsets like UTC minus 5 or UTC plus 9 are just numbers and don't shift. Use named zones in code, and reach for offsets like +09:00 only when you need to display the value to a user.

Why doesn't midnight line up across cities?

Each city's clock advances on its own local schedule. When New York hits midnight, London is already at 5 AM and Tokyo is well into 1 PM. The world clock makes those simultaneous moments easy to compare, which is exactly what you need to answer 'are they asleep?' or 'is this a reasonable time to call?'

Is the data sent anywhere?

No. The math runs in your browser through the standard Date object and Intl.DateTimeFormat. Your chosen cities and any timezone preferences usually stay in localStorage rather than traveling to a server.

World Clock

View current time in different timezones around the world online. Free world clock with multiple city comparison and UTC offsets.

Date & Time

Instant results

UTC

07:53:17 PM

Mon, May 11

UTC

New York

03:53:17 PM

Mon, May 11

UTC-4

London

08:53:17 PM

Mon, May 11

UTC+1

Tokyo

04:53:17 AM

Tue, May 12

UTC+9

Add Timezone

How to Use World Clock

Add cities or timezones

Search for the cities you care about by name, or browse a list of common time zones. Adding three to five at once is when the side-by-side comparison really starts to pay off.

View current times

Each city shows its current local time and updates in real time as the seconds tick by. The display includes the day of week, which matters when one location has already rolled over to the next day.

Compare for scheduling

For an international meeting, scan across the rows for a moment when every participant sits in their normal business hours. The clock turns 'when can we all talk?' from a math problem into a glance.

Save your favorite cities

Most world clocks remember your selected cities across sessions through localStorage, so you don't have to rebuild the same lineup of London, Tokyo, and New York every time you reload.

When to Use World Clock

International business meetings

Scheduling across continents goes wrong fast when nobody can see at a glance who's in working hours. A side-by-side view of every participant's local time stops you from booking a 'quick lunch' that lands at midnight for half the team and makes remote collaboration feel deliberate rather than chaotic.

Tracking family and friends abroad

When loved ones live across time zones, knowing whether they're likely awake before you call saves a lot of awkward voicemails. International students, families running businesses across borders, and expats keeping in touch with home all reach for a world clock more often than they expect.

Travel planning

Before an international trip, glancing at the destination's current time helps you plan how to handle jet lag, when to send 'landed safely' messages, and how to slot calls back home around your schedule. It's the same calculation you'd do mentally, just visible at a glance.

Public displays for global presence

Office lobbies, newsrooms, and trading floors often line up clocks for major financial centers. The message is partly atmospheric — we operate everywhere — and partly practical, helping the people on those floors make real-time calls about coordination, market hours, and breaking news across regions.

World Clock Examples

Major business cities

Input

Cities: NY, London, Tokyo, Sydney

Output

Live readout showing New York at 9:00 AM, London at 2:00 PM, Tokyo at 10:00 PM, and Sydney at 11:00 PM.

This is the classic business pattern. New York's morning overlaps cleanly with London's afternoon, which is why the transatlantic meeting window sits there, while Tokyo and Sydney are deep into the evening with effectively no overlap with US working hours — the East-West gap that hurts truly global teams.

Personal city list

Input

Family in: New York, Berlin, Mumbai, Tokyo

Output

A glance tells you who's likely awake and who's mid-night.

Track family wherever they live so you stop calling your brother in Tokyo at his 3 AM. The same pattern works for friends, flatmates of college kids abroad, or anyone you'd rather not wake up unexpectedly.

DST transition

Input

March/November DST changes

Output

Cities that observe DST shift by an hour while others stay put.

Daylight Saving rules differ by country. The UK springs forward on a different weekend than the US, and Tokyo plus most of Asia simply doesn't observe DST at all, so the displayed offsets shift across regions twice a year. Verify your meeting times after each transition.

Tips & Best Practices for World Clock

1.Add several cities at once rather than one at a time. The pattern only really clicks when you can see three to five locations side by side, which is when the windows of overlap and conflict become visible.
2.Mark your home city distinctly so it stands out at a glance. Treating one row as the anchor makes calculating offsets to the others feel almost automatic.
3.For scheduling, the goal is a time when every participant sits in their normal business hours. The clock is what surfaces those rare overlaps quickly instead of through painful trial and error.
4.Half-hour and quarter-hour zones still trip people up. India runs UTC+5:30, Iran UTC+3:30, Nepal UTC+5:45, and most modern clocks handle them correctly, but it's worth verifying any city you don't normally use.
5.A handful of places skip DST entirely — Hawaii, most of Arizona, and almost all of Asia. Those cities don't shift twice a year, which means the gap between them and your local time changes around DST transitions even though their wall clock doesn't move.
6.For a one-off reference your system clock plus mental math is faster. World clocks earn their keep when you're tracking five or more zones, doing it daily, or putting the result on a public display.

Frequently Asked Questions

It displays the current local time in several cities or time zones at once, all updating in real time. Most people use it to schedule international meetings, work out a sensible moment to call family abroad, keep an eye on overseas business hours, or simply compare what 'right now' looks like in different parts of the world.

World Clock

How to Use World Clock

Add cities or timezones

View current times

Compare for scheduling

Save your favorite cities

When to Use World Clock

International business meetings

Tracking family and friends abroad

Travel planning

Public displays for global presence

World Clock Examples

Major business cities

Personal city list

DST transition

Tips & Best Practices for World Clock

Frequently Asked Questions

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