What is an IANA timezone and why does it matter?

IANA (Internet Assigned Numbers Authority) maintains the canonical timezone database — the same one shipped in every operating system and modern browser. Names like "America/New_York" or "Europe/Berlin" are IANA zones; they encode the full history of DST rules and political boundary changes for each region. Browsers update the database automatically through OS-level patches, so a tool built on Intl.DateTimeFormat always knows the current rules. Using IANA zones (not abbreviations like "EST" or "CET") is the only safe way to handle timezones in code, because abbreviations are ambiguous: "CST" can mean Central Standard Time (US), China Standard Time, or Cuba Standard Time depending on context.

How does the tool handle Daylight Saving Time?

When you enter a wall-clock time in the source zone, the converter computes the actual UTC instant by applying the source zone's offset AT THAT MOMENT — including DST if it was in effect on that date. Then the target zone's offset at the same instant is applied to produce the converted time. This handles the trickiest edge cases correctly: converting 2:30 AM on a spring-forward day, or comparing winter and summer rates across zones with different DST schedules. The DST indicator on each clock tile is computed per-instant, not per-zone, so it can correctly say "DST active" on April 15 even though the zone observes DST only part of the year.

Why does this not use timezone abbreviations like EST or PST?

Two reasons. First, abbreviations are ambiguous — "CST" alone means Central Standard Time, China Standard Time, or Cuba Standard Time depending on who is reading. Second, abbreviations encode whether DST is active in their name (EST vs EDT, PST vs PDT) so they cannot be used as a single identifier across the year. IANA zone names like "America/New_York" stay constant year-round and the offset shifts with DST internally. Our converter accepts the full IANA list (typically 400+ entries) and displays the appropriate abbreviation alongside the offset for human reference.

What does "UTC offset" mean?

UTC offset is the number of hours and minutes a region is ahead of (positive) or behind (negative) Coordinated Universal Time. For example, New York is UTC-05:00 in winter and UTC-04:00 in summer (DST); India is always UTC+05:30 (no DST, half-hour offset). The offset can change at DST transitions, but UTC itself never changes — it is the atomic-clock reference time used by GPS, internet protocols, and aviation. When converting times, always pivot through UTC: source-zone-time → UTC instant → target-zone-time.

My team is global — how do I pick a meeting time?

Add each team member's city to the world clock board. Glance across the row to find an hour where every city shows a reasonable working time (say 8 AM to 6 PM local). For three time zones spanning 9+ hours (e.g., San Francisco, London, Mumbai), there is often no overlap that is comfortable for everyone — rotate inconvenience across recurring meetings. The clock tiles also show day-of-week, which matters when working with cities across the international date line.

Does this work offline?

Yes, once the page is loaded. The IANA timezone database is built into your browser's ICU implementation; Intl.DateTimeFormat does not need a network call to compute offsets or format dates. You can disconnect from the internet, change your system clock, and the converter will keep working correctly. The only network requests are for the page itself and our static assets — never for time data.

Why are there so many timezones in the dropdown?

The IANA database includes ~400+ zones because boundaries follow political subdivisions, not just longitude. Indiana alone has multiple zones because some counties opt out of DST; Russia has 11 zones spanning its territory. Many entries are "alias" zones for backward compatibility (e.g., "America/Buenos_Aires" links to "America/Argentina/Buenos_Aires"). For most practical use, stick to capital-city or major-city zone names. If you need to find a specific city, search the dropdown — typing "Tokyo" filters to Asia/Tokyo, etc.

How is this different from converting timestamps in JavaScript?

A plain JavaScript Date object stores a UTC instant, but its string representation depends on the runtime's local timezone, which varies by user. This converter lets you SPECIFY both source and target zones explicitly, decoupling the math from the user's system timezone. Internally we use Intl.DateTimeFormat with the timeZone option (added to the spec around 2017, supported everywhere now) — the same approach modern date libraries like date-fns-tz and Luxon use under the hood.

Can I share a converted time as a link?

Not yet in the URL — but the ISO 8601 output (e.g., "2026-05-11T14:30:00.000Z") is an unambiguous, shareable timestamp. Anyone receiving that string can paste it into our converter or any timezone-aware tool and see the wall-clock time in their own zone. ISO 8601 is the only safe way to communicate a specific instant in text-based formats (emails, Slack, etc.); never write "Wednesday at 3 PM" without specifying which timezone's Wednesday.

Free Time Zone Converter With Live World Clock & DST Status

Convert a specific time between any two IANA timezones, or open a live world-clock board showing nine cities at once. Native browser timezone database (every IANA zone), DST awareness, and UTC-offset display. 100% client-side via Intl.DateTimeFormat.

Convert Specific Time

12-hour format

From

Now in UTC:

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UTC offset —

Live World Clock

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