Time Zone Converter — Convert Between Any Two IANA Zones

What is Timezone Converter?

A time zone converter takes a moment in time expressed as a wall-clock in one zone (e.g. '9:30 AM in New York on July 15') and reprojects it into other zones (what time is that in Tokyo? Sydney? UTC?). The tricky part is not the offset arithmetic — it's daylight saving time. The correct offset for the same zone can be different in July vs. December, and near the DST transition, wall-clock times can be ambiguous or non-existent. This tool relies on the browser's Intl API (backed by the IANA / TZDB database), which is kept up to date as governments change their DST rules — a moving target that hand-rolled offset math tends to get wrong. Every calculation runs entirely locally.

How to convert time between time zones

1. 1Pick a source time zone (defaults to your browser's local zone).
2. 2Enter the date and time as observed in that source zone.
3. 3The tool computes the UTC instant behind the scenes and renders it in every target zone in the grid.
4. 4Add or remove target zones with the '+' card and the ✕ button on any card.
5. 5Click 'Now' at any time to reset the input to the current moment in the source zone.

Use Cases

Key Concepts

IANA time zone

The canonical name of a time zone in the IANA time zone database (also called tzdata or TZDB), like America/New_York. IANA names encode both the current UTC offset and DST rules, and are updated as governments change their laws.

UTC vs. GMT

For everyday use these are interchangeable. Technically UTC is a time standard maintained by atomic clocks with periodic leap-second adjustments; GMT is a time zone at longitude 0°. This tool uses UTC labels internally and matches whatever notation the browser exposes (usually 'GMT±HH:MM').

Daylight saving time (DST)

Many jurisdictions shift clocks forward by one hour in spring and back in autumn. The Intl API knows the exact rules for each zone and year. When crossing a DST boundary, the offset changes even though the zone name doesn't.

Ambiguous & non-existent times

On the 'fall back' day, 1:00–2:00 AM local time happens twice. On the 'spring forward' day, 2:00–3:00 AM doesn't exist at all. Ambiguous times default to the earlier occurrence in this tool; non-existent times default to the later one.

Tips & Best Practices

• ▸Prefer IANA names (America/New_York) over abbreviations (EST) — abbreviations are ambiguous (EST could mean US Eastern or Australian Eastern) and can't express DST correctly.
• ▸For scheduling systems, always store the target moment as UTC + the IANA zone the user picked. Converting to wall-clock at render time is the safe pattern.
• ▸When a zone changes its rules (e.g. a country abolishes DST), browsers eventually update via OS-level TZDB updates. If your project is critical, ship your own tzdata rather than trusting each user's browser.
• ▸This tool works fully offline — save the page and re-open on a plane / air-gapped machine.