Time zone converter
Pick a date and time in one city and see it in every other city you care about at once, with daylight saving applied for that exact date. Free, no signup, and nothing leaves your browser.
- New York · UTC-4 · DSTSat, Aug 29, 12:00 PM
- London · UTC+1 · DSTSat, Aug 29, 5:00 PM
- Tokyo · UTC+9Sun, Aug 30, 1:00 AM
How do you convert between time zones?
Take the source time, subtract its UTC offset to get the UTC instant, then add the target zone offset. New York in January is UTC-5, so 09:00 there is 14:00 UTC; Berlin is UTC+1, so the same moment is 15:00. The step people skip is that offsets change with daylight saving, which is why converting with a memorised number is wrong for several weeks a year.
Does this handle daylight saving time?
Yes. Offsets are read from the IANA time zone database for the exact date you pick, not from a fixed table, so a meeting in March converts differently from the same wall-clock time in January. Southern hemisphere zones are handled too, where summer time runs over the northern winter.
Why is the time difference between two cities not constant?
Because the two zones usually switch to daylight saving on different dates, and some do not switch at all. New York and London are normally 5 hours apart, but for about two weeks each spring and autumn they are 4, because the US and the EU change on different weekends. Arizona, most of Asia and most of Africa do not observe it at all.
What is UTC?
Coordinated Universal Time, the reference every zone is defined against. It does not observe daylight saving, which is why servers, aviation and international scheduling use it. GMT is the same clock time in practice, though technically a different standard.
Common offsets, and when they move
Offsets below are standard time. The last column is when the zone switches, which is the part that makes a remembered difference wrong twice a year.
| City | Standard | Daylight saving |
|---|---|---|
| Los Angeles | UTC-8 | Second Sunday in March to first Sunday in November |
| New York | UTC-5 | Second Sunday in March to first Sunday in November |
| London | UTC+0 | Last Sunday in March to last Sunday in October |
| Berlin, Paris | UTC+1 | Last Sunday in March to last Sunday in October |
| Dubai | UTC+4 | None |
| Mumbai | UTC+5:30 | None |
| Singapore, Shanghai | UTC+8 | None |
| Tokyo | UTC+9 | None |
| Sydney | UTC+10 | First Sunday in October to first Sunday in April |
The three-week window where everyone is wrong
New York and London are five hours apart, except they are not. The US moves to daylight saving on the second Sunday in March and the EU on the last Sunday, so for roughly three weeks each spring the gap is four hours rather than five. The autumn switch opens a shorter window in the other direction.
Everyone who schedules across those two cities has been caught by this at least once, and it is not carelessness. It is that the difference between two zones is not a property of the pair, it is a property of the pair on a particular date. Converting against the actual date, which is what this page does, is the only version that holds.
Or stop filling these in
A calculator can only add up what you remembered to write down, and what you write down a week later is smoother and more purposeful than the week was. Cronus records which app and window you were in and works out what the time was in service of, automatically. No timer to start, so the chaotic days produce a record instead of a gap.
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Related: military time converter, time duration calculator, and meeting cost calculator.