One moment · many clocks
Time Zone Converter
Name a date and time in one zone and read it in as many others as you need, with the correct daylight saving rules for that date rather than for today.
| Zone | Local time | Date | Offset | Difference |
|---|
The difference column compares each zone with the source zone above.
Why this is harder than it looks
Four Things That Break Time Zone Maths
Offsets Are Not Zones
Storing "+01:00" instead of "Europe/Berlin" throws away the rules. Come the last Sunday in March, the stored offset is wrong and every recurring event built on it shifts by an hour. Store the zone name and let the database do the arithmetic.
Clock Changes Are Not Synchronised
Europe and North America change on different weekends, the southern hemisphere moves the other way, and much of Asia and Africa does not change at all. For a few weeks each spring and autumn the usual gap between two cities is not the usual gap.
Some Local Times Do Not Exist
When clocks jump forward, an hour is skipped. In the UK, 01:30 on the spring change date simply never happens. Ask software to schedule something then and it has to guess. Times can also occur twice in autumn, which is worse.
The Rules Change with Politics
Countries adopt, drop and shift daylight saving with little notice, and the time zone database is updated several times a year to keep up. A system that has not been updated recently can be confidently wrong about a country that changed its rules last month.
Answers
Time Zone Questions
Daylight saving, odd offsets, date boundaries and why zones beat offsets.
How do I convert a time between two zones?
Enter the date and time, say which zone that time is in, and every zone in the list updates to show the same instant expressed locally. You are not converting a number so much as naming one moment and asking what each place calls it.
Why does one city show a different date?
Because the world spans more than a day. When it is Saturday evening in New York it is already Sunday morning in Tokyo. Date errors are the most common scheduling mistake across the Pacific, which is why the date is shown beside every time rather than only the clock reading.
Does it handle daylight saving?
Yes, and for the date you enter rather than for today. If you convert a time in July while it is January, the summer offset is used, because your browser carries the full time zone database with every historical and future rule in it. This is exactly the case that manual offset arithmetic gets wrong.
Why do some zones differ by 30 or 45 minutes?
Because zones are political decisions rather than neat slices of longitude. India runs at UTC+5:30, Nepal at UTC+5:45, and the Chatham Islands at UTC+12:45. Any calculation that assumes whole hours breaks in those places.
Which zone should I use when writing an invitation?
UTC, with local equivalents in brackets for the people who need them. Better still, send a calendar invitation, which converts automatically for each recipient and removes the possibility of error entirely.
What is the difference between a time zone and a UTC offset?
An offset is a number, like +02:00. A time zone is a place with rules, like Europe/Berlin, which is +01:00 in winter and +02:00 in summer. Storing an offset loses the information needed to work out what happens after the next clock change, which is why software should store zones rather than offsets.
Can I share a converted time with someone?
Press copy link and the address carries the moment you selected. Whoever opens it sees the same instant expressed in the zones on their screen, so there is nothing to misread.