Timezone Converter

Runs in browser Utilities

Convert any moment across IANA timezones with DST awareness, compare several zones at once, and copy ISO strings with the correct offsets.

Privacy: This tool runs entirely in your browser. Your input never leaves your device.

What is an ISO 8601 timestamp, and how does it relate to Unix time?

ISO 8601 writes a moment as 2026-09-23T10:15:00+03:00 — largest unit first, with an explicit UTC offset or Z — so it sorts as text and is unambiguous across locales; RFC 3339 is the Internet profile APIs use. Unix time is the same moment as a count of seconds (or milliseconds in JavaScript) since 1970-01-01T00:00:00Z, with no time zone at all. Most date bugs are an offset applied twice or a local time stored as if it were UTC.

How to use Timezone Converter

  1. Type the date and time as seen in the source zone (or use an epoch / ISO value with an offset).
  2. Pick the From and To zones.
  3. Add extra zones to compare in the world clock table.

Timezone Converter features

  • Every IANA timezone supported by your browser, with popular Middle-East, Asian, European and American zones first
  • DST-aware offsets and abbreviations for the exact instant
  • Difference between the two zones and day shift (next / previous day)
  • World clock table with any extra zones you add
  • ISO strings for source, target and UTC plus a datetime-local value

Timezone Converter example

Riyadh stand-up in other offices

Input:

2024-03-15 09:00 · From Asia/Riyadh · To America/New_York

Output:

New York: Friday, 15 March 2024 02:00 (UTC−04:00 EDT)
New York is 7 hours behind Riyadh

Frequently asked questions about Timezone Converter

Where does the timezone data come from?

From your browser's built-in Intl.DateTimeFormat, which ships the IANA tz database including daylight-saving rules. No external library or server is involved.

Does it handle daylight saving time?

Yes. Offsets are computed for the specific instant, so London shows +01:00 in summer and +00:00 in winter, and Riyadh stays at +03:00 all year.

How do I enter a time in the source zone?

Type it without an offset (2024-03-15 09:00) and pick the "From" zone. If you include Z or an offset, or an epoch number, the value is absolute and the "From" zone only affects the display.

Can I compare more than two zones?

The world clock table lists common zones automatically and you can add any IANA names in the "Extra zones" field, separated by commas.

Technical notes

Offsets are not looked up in a table: for the exact instant the engine formats the date with Intl.DateTimeFormat in the zone, rebuilds the wall-clock parts as UTC and diffs them (offsetMinutes), rounded to whole minutes — so Local Mean Time before standard time (Riyadh +03:06:52 until 1947) prints as +03:07. 'Difference' compares both offsets at that instant and therefore changes across DST; 'next day / previous day' compares calendar dates.

A wall-clock time without an offset is resolved by guess → offset → re-check (zonedToUtc): a time inside a spring-forward gap moves forward by the length of the gap (New York, 10 March 2024: 02:30 becomes 03:30 EDT); an ambiguous fall-back time takes its first, daylight-saving occurrence. Abbreviations are en-US short zone names, so North American zones show EDT or PST but most others GMT+3; Extra zones accepts any identifier the browser recognises, even aliases like US/Eastern.

In New York on 10 March 2024 the wall-clock times 02:00–02:59 never happen, so a 02:30 typed without an offset comes back as 03:30 EDT.

New York wall-clock time, 10 March 2024

Axis from 00:00 to 05:00
  • 00:00–01:59EST · UTC−05:00
  • 02:00–02:59Skipped hour
  • 03:00–04:59EDT · UTC−04:00
  1. 102:30 EnteredInside the spring-forward gap: no such time in New York that day.
  2. 203:30 EDT Returned by the toolMoved forward by the skipped hour; in UTC 07:30:00Z.

UTC has no gap: 01:59:59 EST is 06:59:59Z, and one second later the clock reads 03:00:00 EDT, 07:00:00Z. Values are the tool’s output for America/New_York.

References