Timezone Converter
Runs in your browserConvert a time between any two IANA timezones — DST handled correctly. Includes a live world clock for quick reference.
Convert Time
16:05
20:05 UTC — Coordinated Universal Time = 16:05 New York (ET)
Live World Clock
New York16:05:19Thu, May 7
London21:05:19Thu, May 7
Paris22:05:19Thu, May 7
Dubai00:05:19Fri, May 8
India01:35:19Fri, May 8
Shanghai04:05:19Fri, May 8
Tokyo05:05:19Fri, May 8
Sydney06:05:19Fri, May 8
Runs entirely in your browser — nothing is uploaded
Runs in your browser
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How to Convert Between Time Zones
Timezone Converter uses the browser's built-in Intl.DateTimeFormat API with a timeZone option set to an IANA zone name (like 'America/New_York' or 'Asia/Tokyo'). The browser ships with a copy of the IANA Time Zone Database (often called tzdata or zoneinfo), and the formatter applies the correct UTC offset for your specific date — including all historical DST rules, leap seconds, and political shifts.
Daylight Saving Time is handled automatically because the IANA database encodes every transition in history. A conversion from New York to London on July 15 correctly applies EDT (UTC-4) to BST (UTC+1) for a five-hour gap; the same conversion on January 15 applies EST (UTC-5) to GMT (UTC+0) for the same five-hour gap. You don't have to know which zone is currently observing DST.
There's a real but rarely-encountered staleness issue: the IANA database is updated several times a year as countries change their DST rules (Egypt, Mexico, Lebanon, and Russia have all made changes since 2014). The version of tzdata your browser ships with may lag the latest IANA release by a few months. For dates in 2026 onward, double-check against an official source if a country recently announced rule changes.
Around DST transitions, two ambiguities exist: 'spring forward' creates a gap (2:30 AM on transition day doesn't exist in clock time, since clocks jump from 2:00 to 3:00) and 'fall back' creates an overlap (1:30 AM happens twice). The Intl API resolves these by choosing one interpretation — typically the standard-time reading. If precision matters around 2 AM on a transition day, prefer UTC input.
The +1 day / -1 day badge appears when the converted local date differs from the input date. New York 11 PM on Friday is Saturday 4 AM (or 5 AM during winter) in London, so the result shows '+1 day.' This is computed by comparing the day-of-month between the formatted source and target.
All conversion runs locally in the browser. There's no API call to a timezone service, no logging of the times you convert, and no analytics field with the values. Refresh the tab and the inputs reset.
If you need to schedule a recurring meeting across zones (e.g., 'every Tuesday 9 AM London time'), check the meeting time in each zone for the next DST transition month — the gap can shift by an hour twice a year, which surprises everyone the first time.
Common Use Cases
01
Remote team scheduling
Find overlapping working hours for distributed teams without spreadsheet math or guesswork.
02
Meeting coordination
Schedule international calls at times that respect everyone's working day after DST transitions.
03
Deployment windows
Plan server maintenance during low-traffic windows in your largest user region (e.g., 3 AM Tokyo time).
04
Travel arrival planning
Compute local arrival times after long-haul flights to plan ground transport and check-in.
Frequently Asked Questions
Yes. The Intl.DateTimeFormat API uses the IANA tz database, which encodes every DST rule and historical transition. Conversions automatically apply BST vs GMT, EDT vs EST, AEST vs AEDT, etc., based on the date you pick.
All ~600 IANA timezone identifiers, covering every named zone worldwide. The picker shows common cities, but the underlying API supports any valid IANA name like 'Pacific/Auckland' or 'America/Argentina/Buenos_Aires'.
When the converted time crosses midnight relative to the input, the result shows +1 day (next day) or -1 day (previous day) so you don't accidentally schedule a meeting on the wrong calendar date. Common when converting late-night times across the Atlantic or Pacific.
Click the swap icon between From and To to reverse the direction. The input time stays fixed while the source and target zones swap, so you can quickly see 'what time is 3 PM London in NY' and 'what time is 3 PM NY in London.'
That's DST. Different countries shift to/from DST on different dates — the EU shifts the last Sunday of March/October, the US shifts the second Sunday of March and first Sunday of November. There's a 1-3 week window each spring and fall when the offset between any two zones differs from the rest of the year.
Yes — pick UTC (or any equivalent like Etc/UTC) as the source zone. The Intl API parses the time as a UTC instant and formats it in the target zone's local time. For Unix epoch values, use the Timestamp Converter tool which handles seconds-since-1970 directly.
Browsers ship with a snapshot of the IANA tz database that updates with browser releases (typically every 4-8 weeks). If a country changes rules between database updates, conversions for dates in the future may be slightly off. For mission-critical schedules around recently-changed rules, verify against an official government source.
Yes. Samoa skipped December 30, 2011 to move from UTC-11 to UTC+13, and the IANA database records this. Conversions across the date line (Auckland vs Honolulu, for example) correctly show the +1 or -1 day badge.
No. The Intl API runs in V8/JavaScriptCore inside your browser. There's no network call to a timezone service, no logging, and no persistence of the times you enter.
The IANA database includes pre-1970 timezone history (when many regions had different offsets or hadn't adopted standard time at all). The browser supports these but accuracy depends on the data; very early 20th-century dates in some regions may be approximate.
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