Time Zone Converter
See what a chosen time is in cities around the world, using your device’s own time zone data.
Processed on your device — no upload
Daylight saving is applied automatically for the date you pick, using the rules already in your browser — so a meeting in March converts differently from the same meeting in July.
How to use it
- Choose a city and the time there.
- Set the date — daylight saving depends on it.
- Read that same moment in every other city.
How it works
Your browser already carries the complete IANA time zone database: every zone, every offset, every daylight saving rule, and the history of when those rules changed. This tool asks the browser rather than fetching anything, which is why it works offline.
The calculation converts your chosen wall-clock time into a single instant, then asks what that instant reads as in each other zone. Going from a wall time to an instant is the awkward direction — it needs the offset, which depends on the date — so the tool makes an initial guess, measures how far it lands from the target, and corrects. One pass handles every real offset, including the half-hour and three-quarter-hour ones.
The date field is not optional detail. The same 14:00 in Amman converts differently in March than in July, because the northern hemisphere shifts in and out of daylight saving on dates that differ by country. Europe and North America do not change on the same weekend, so there are two weeks each spring and autumn when the usual difference between London and New York is simply wrong.
The day of the week is shown beside every city because it changes. Scheduling across Asia and the Americas regularly crosses midnight, and a meeting at 09:00 Tuesday in Tokyo is Monday evening in Los Angeles.
A worked example
You are in Amman arranging a call with colleagues in London and New York, and you propose 14:00.
In July that is 12:00 in London and 07:00 in New York. London works. New York is early but survivable.
Now change the date to January. The same 14:00 in Amman becomes 12:00 in London and 06:00 in New York — an hour earlier for New York than the summer answer, because the three regions leave daylight saving at different times.
This is the mistake behind most missed international meetings. A recurring invitation set in summer quietly shifts for some participants when the clocks change, and only for some of them.
The date-change case. Set the city to Sydney at 09:00 and look at Los Angeles: the day beside it is the previous day. A Monday morning meeting in Sydney is Sunday afternoon in California, which is why the day label sits next to every city rather than being assumed.
A practical habit for scheduling across many zones: pick UTC as your reference, agree the UTC time, and let each participant convert. UTC has no daylight saving, so it cannot drift.
For a duration rather than a moment, the time unit converter handles hours and minutes.
Questions
How do I see the time difference between cities?
Pick two zones and the offset is shown for the date you choose, with daylight saving already applied. It works as a world clock for scheduling across countries.
Where does the time zone data come from?
Your browser. Every modern browser ships the full IANA time zone database, including daylight saving rules and their history, so nothing is fetched and the tool works offline.
Does it handle daylight saving?
Yes, automatically, for the date you choose. That is why the date field matters — the same time converts differently in March than in July.
Why does the day of the week differ between cities?
Because time zones span more than a day's worth of offsets. 09:00 Monday in Sydney is Sunday afternoon in Los Angeles. The day is shown beside every city for that reason.
Why do the usual differences break for a couple of weeks a year?
Europe and North America change their clocks on different weekends, so for those weeks the normal gap between London and New York is an hour out.
What is the safest way to schedule across zones?
Agree a UTC time and let each participant convert. UTC has no daylight saving, so it cannot drift under you.
Is anything uploaded?
No. The conversion uses data already on your device and nothing is transmitted.
Can I add a city that is not listed?
Not currently. The list covers major business hubs across the main offsets; a full list of every IANA zone would run to hundreds of entries.
What does the offset beside each city mean?
Its difference from UTC on the date you chose — GMT+3 for Amman in summer, for example. It changes with daylight saving, which is why it is shown per date.
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