Victor
Creator and maintainer, City Clock
Victor builds and maintains City Clock. He writes the guides and articles here, and maintains the city and time zone dataset the site runs on.
Convert Time Between Zones
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To
How to Use the Time Zone Calculator
Step 1: Enter Source Information
Select the date, time, and time zone you want to convert from. The calculator defaults to your current date and time.
Step 2: Choose Target Time Zone
Select the time zone you want to convert to from the dropdown list of common international time zones.
Step 3: Get Instant Results
Click "Convert Time" to see the equivalent time and date in your target time zone, automatically accounting for daylight saving time.
Quick Tips
Meeting Scheduling
Use this calculator to find the best meeting times that work across multiple time zones.
Travel Planning
Convert flight times and arrival schedules to avoid confusion when traveling internationally.
DST Automatic
The calculator automatically handles daylight saving time transitions for accurate conversions.
Popular Conversions
How time zone conversion actually works
Converting a time between two places is not arithmetic on time zones. It is arithmetic on offsets, and the offset a place uses depends on the date you are converting. That distinction is the source of almost every conversion error people actually make.
A time zone is a set of rules — "this region is UTC+01:00, except between these dates when it is UTC+02:00, and before 2016 it also did X". The calculator above resolves both cities to their offset on the date you pick, using the IANA time zone database, and converts between those. It is the same database operating systems use, which is why the answer matches your phone.
Four things that break the simple mental model
The gap between two cities is not constant
London and New York are five hours apart for most of the year. For about two weeks each March they are four, because the United States moves to daylight saving on the second Sunday in March while Europe waits until the last Sunday. A one-week mismatch happens again in autumn.
If you convert a date inside one of those windows using the offset you remember from last month, you will be an hour out — and nothing will warn you.
Most of the world does not change clocks
Of the 242 IANA zones this site covers, only 58 observe daylight saving. Japan, India, China and almost all of Africa keep a fixed offset year-round.
That does not make them simpler to work with. When your clocks shift and theirs do not, the difference between you changes anyway — so a recurring call drifts by an hour even though nothing changed at their end.
Not every offset is a whole hour
India runs at UTC+05:30, Iran at UTC+03:30, Afghanistan at UTC+04:30, Nepal at UTC+05:45 and the Chatham Islands at UTC+12:45. Newfoundland sits at UTC−03:30 and shifts to UTC−02:30 in summer.
Ten of the zones here are on a half- or quarter-hour offset. Any calculation that rounds to the nearest hour is simply wrong for those places, all year.
The rules themselves change
Turkey abolished seasonal clock changes in 2016, Iran in 2022, Namibia in 2017 and Paraguay in 2024. Kazakhstan merged its two zones into one in 2024. Morocco shifts twice a year around Ramadan rather than for summer, so its dates move about eleven days earlier each year.
Converting a date in the past means using the rules that applied then, not now. A conversion tool that ignores history will quietly misreport historical timestamps.
A worked example
Suppose you are in London and want to schedule a call with a colleague in Mumbai for 09:00 your time, on a date in July.
- London in July is on British Summer Time, UTC+01:00. So 09:00 local is 08:00 UTC.
- Mumbai is on India Standard Time, UTC+05:30, and India does not observe daylight saving — so that offset holds in July exactly as it does in January.
- 08:00 UTC plus 5 hours 30 minutes is 13:30 in Mumbai.
Now move the same meeting to January. London reverts to UTC+00:00, Mumbai does not move, and 09:00 London becomes 14:30 in Mumbai. The meeting shifted an hour in Mumbai's day without anyone touching the invite — which is exactly the failure this calculator exists to prevent.
Limitations worth knowing
- Times that do not exist. When clocks spring forward, an hour is skipped. In most of Europe on the last Sunday in March, 02:30 local time simply never happens. A conversion for a non-existent local time has no correct answer, only conventions.
- Times that happen twice. When clocks go back, an hour repeats. "01:30 on the last Sunday in October" is ambiguous in much of Europe — it occurs once before the change and once after.
- Future dates are predictions. Governments change time zone rules, sometimes with only weeks of notice. A conversion for a date two years out reflects today's rules, not a guarantee.
- Country is not enough. Australia, the United States, Brazil, Russia, Canada, Indonesia and the DR Congo all span multiple zones. Always convert by city.
When to use which tool
Use the calculator above when you have a specific time and date to translate between two places. It answers "what is 09:00 London on 12 March in Mumbai".
Use the meeting scheduler instead when you do not yet have a time — when you need to find a window that works across three or more locations. That is a search problem rather than a conversion problem.
And use an individual city page when you want the standing facts for one place: its current time, whether it changes clocks and on what dates, and how its working day overlaps with yours.