Are daylight-saving changes handled?

Yes. Times are computed with your browser built-in IANA time-zone database — the same one your operating system uses — so daylight-saving transitions are applied automatically.

Which time zones can I add?

Any IANA zone your browser knows, listed by region and city (for example America/New_York or Pacific/Auckland). Older browsers fall back to a curated list.

What is the difference between this and the multi-city clock?

This tool lets you pick raw IANA zone identifiers like Europe/London or Asia/Tokyo directly, which is useful for developers and precise scheduling. The multi-city version presents the same data labelled by familiar city names.

What is a UTC offset?

It is how many hours a zone is ahead of or behind Coordinated Universal Time. London is UTC+0 in winter and UTC+1 in summer; New York is UTC-5 or UTC-4. The clock shows each zone's current offset.

Can I show 12-hour AM/PM time?

Yes. Toggle the 12-hour option to display AM and PM, or leave it off for 24-hour time across every zone in your list.

How do I compare two zones quickly?

Add both and look at each one's "ahead of or behind your device" value. The gap between those two numbers is the time difference between the zones.

Is any clock data fetched from a server?

No. The current time comes from your device clock and all conversions happen locally — nothing is fetched or sent.

What is the World Clock — Multiple Time Zones?

Free world clock that shows the live time across multiple IANA time zones side by side, with offsets and the difference versus your device. DST-accurate and 100% in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

World Clock — Multiple Time Zones

Name: World Clock — Multiple Time Zones
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

See every time zone at once

This world clock compares the live time across any IANA time zones side by side. You add the zones you care about by their standard identifier — such as Europe/London, America/New_York, or Pacific/Auckland — and each row updates every second. It is built for developers, remote teams, and anyone scheduling across regions who wants precise zone control rather than just city names.

How it works

Each second, the tool takes your device’s current instant and renders it in every selected zone using the browser’s built-in IANA time-zone database via the Intl API. That database encodes every zone’s daylight-saving rules and historical offsets, so transitions are applied automatically and even fractional offsets (like Asia/Kolkata at UTC+5:30) are correct. Every row shows the zone’s current UTC offset and the difference versus your own device.

Column	Meaning
Local time	Live time in that zone
UTC offset	Current hours from UTC
Vs your device	Hours ahead of or behind you

Worked example

Add Asia/Tokyo and America/Los_Angeles. Tokyo shows UTC+9 and Los Angeles UTC-7 (in summer PDT), a 16-hour gap. So when it is 10:00 Monday in Los Angeles, it is already 02:00 Tuesday in Tokyo — instantly visible without manual maths. In winter, Los Angeles shifts to UTC-8, widening the gap to 17 hours.

Why IANA identifiers instead of city names

IANA time zone identifiers like America/New_York or Europe/Berlin are the foundation of how operating systems and programming languages handle time globally. They encode not just the current offset, but the full history of every offset change and daylight-saving transition for that region going back decades. This means:

Daylight-saving transitions are exact. The clock knows that America/New_York switches from UTC-5 to UTC-4 on the second Sunday in March, not just that New York is “UTC-5.”
Historical accuracy. Scheduled meetings stored as a Unix timestamp display correctly even if the local DST rules changed between when the meeting was booked and when it occurs.
No ambiguity. “Eastern Time” could mean EST or EDT. America/New_York is always precise.

Using this tool with the raw identifiers is particularly useful for developers and operations teams who work with timestamps and need to verify the exact offset in a specific zone at a specific moment.

Useful zone combinations for common schedules

Some of the most frequently needed multi-zone comparisons:

Scenario	Zones to add
US cross-coast	America/New_York · America/Los_Angeles
US + EU	America/New_York · Europe/London · Europe/Berlin
London + India + Singapore	Europe/London · Asia/Kolkata · Asia/Singapore
US West Coast + Japan	America/Los_Angeles · Asia/Tokyo
UK + US + Australia	Europe/London · America/Chicago · Australia/Sydney

Fractional offsets worth knowing

Not all time zones are whole hours from UTC. Several widely-used zones run on 30-minute or 45-minute offsets:

Asia/Kolkata (India): UTC+5:30
Asia/Colombo (Sri Lanka): UTC+5:30
Asia/Kabul (Afghanistan): UTC+4:30
Asia/Kathmandu (Nepal): UTC+5:45
Australia/Adelaide: UTC+9:30 (standard) / UTC+10:30 (summer)
Pacific/Marquesas: UTC−9:30

These fractional offsets can catch you out when computing differences manually; using the clock directly avoids the arithmetic entirely.

Conversions use your browser’s built-in time-zone database, so daylight-saving transitions are handled for you — and no clock data is ever fetched or uploaded.