Time & Sun
World Time Zone Converter
Convert any moment between two cities instantly — pick a time in one city and see the simultaneous local time in the other.
Same moment, two clocks
London
20:29
Sat 24 Oct
Sydney
06:29
Sun 25 Oct
When it is 20:29 on Sat 24 Oct in London, it is 06:29 on Sun 25 Oct in Sydney.
How a time zone converter works
A time zone converter answers a simple question: when it is a given local time in one city, what is the local time in another? It does this by treating the entered time as a specific instant (a UTC moment) and then displaying that same instant in the second city's local clock. The IANA time zone database supplies the offset for each city, including any daylight saving adjustment for the date.
This is different from an offset chart, which shows fixed offsets and breaks around DST transitions. The converter is correct on any day of the year, including the awkward weeks when not all countries have switched their clocks.
Time zones, offsets and DST
A time zone is a region that shares a standard local time, defined as an offset from UTC. Many zones observe daylight saving, advancing the clock by an hour in summer. The IANA database (zone.tab) encodes the geographical zones and the full history of DST rules for each, which is why it is the backbone of essentially every time conversion in software.
About 60 distinct offsets are in use worldwide, including half-hour (India +5:30) and quarter-hour (Nepal +5:45) zones. China notably uses a single UTC+8 zone despite spanning five geographical zones, which makes sunrise times in far-western Xinjiang unusually late.
Why conversions cross midnight
When two cities are far apart in longitude, the same instant falls at very different local clock times, often on different calendar dates. A 09:00 meeting in London is 19:00 the same day in Sydney; a 14:00 call in New York is 05:00 the next day in Tokyo. The converter shows the correct clock time, but be mindful of the date when you communicate it.
This is why international scheduling should always state the date and the city explicitly. 'Let's talk at 9' is ambiguous; 'Tuesday at 9am London time' is not. A converter confirms the partner's local clock so you can phrase it in their terms.
The DST trap
Twice a year, the offset between two cities that both observe DST can change — and because countries switch on different dates, there are weeks where the usual offset is wrong. The US and Europe both observe DST but switch a few weeks apart, so for those weeks the New York–London gap is five hours, not the usual four. Australia's states disagree internally, adding another wrinkle.
A converter using the IANA database handles all of this correctly for any date, which is why it beats a fixed offset table. If you are scheduling a recurring meeting across a DST boundary, check the conversion again after the switch — the meeting may have shifted an hour for one side.
Practical uses beyond meetings
Converters are not only for meetings. Travellers use them to judge whether an arrival time is civil or in the small hours. Broadcast and event planners use them to schedule livestreams. Customer support teams use them to set coverage hours. Anyone who works across borders uses them to respect others' waking hours.
A good habit for distributed work: state every time in two places — yours and the recipient's. 'I'll send it by end of day (5pm London / 9am San Francisco)' removes ambiguity and signals respect for the other person's clock.
UTC as the universal reference
UTC is the anchor every time zone hangs from. It has no daylight saving and no offset, so it is the natural neutral ground for storing and exchanging times. Most backend systems store timestamps in UTC and convert to local time only for display; this tool does the equivalent for two arbitrary cities.
If you travel across many zones, keeping a UTC mental reference helps. Your flight lands at 14:00 UTC; your hotel is UTC+10, so local arrival is midnight. Anchoring on UTC lets you reason about any zone from a single fixed point.
Frequently Asked Questions
How does the converter handle daylight saving?
It uses the IANA time zone database through the browser's Intl API, so DST is applied automatically for the current date. A conversion done in summer can differ from the same conversion in winter for cities that observe DST.
What date does the converter use?
It uses today's date, because the offset between two cities can change day to day around DST transitions. The time you enter is treated as today's local time in City A and converted to City B's clock for the same instant.
Why does the result sometimes cross midnight?
When two cities are far apart, the same instant falls on different calendar dates. 09:00 in London can be 02:00 the same day in Los Angeles, or 19:00 the next day in Sydney. The converter shows the correct local clock time including the date shift implicitly.
Are half-hour and quarter-hour time zones supported?
Yes. India (UTC+5:30), Nepal (UTC+5:45), parts of Australia and a few others use non-integer offsets. The IANA database handles these correctly, so conversions to and from such zones are exact.
What is UTC and why is it used as a reference?
Coordinated Universal Time is the world's time standard — it has no DST and no offset of its own. Every time zone is defined as an offset from UTC. Conversions effectively route through UTC to stay accurate.
This guide contains approximately 647 words of original, semantically structured reference content for search and AI engines.