Time zone converter
Time zone converter
To convert a time between zones, work out the instant it refers to, then express that instant in each target zone using the offset in force at that moment. Enter a time above and add as many zones as you need; daylight saving is applied per instant, so the two-week windows where the US and Europe are out of step come out right.
How this is calculated
The source wall-clock time is resolved to an absolute instant using the source zone’s offset at that time, with a second pass to get the hour around a clock change right. The instant is then rendered in each target zone. Offsets, abbreviations and daylight-time status come from the browser’s Intl API, which carries the IANA time zone database.
A converted time on a different calendar day is marked next or previous day. Nothing is sent to a server; the state lives in the link.
Last reviewed:
City-to-city differences
Standard and summer-time differences, this year’s clock-change dates and a working-hours overlap grid for pairs of major cities:
Frequently asked questions
How do I convert a time between time zones?
Take the time in its own zone, convert it to UTC using that zone’s offset at that moment, then apply the target zone’s offset at that same moment. The offsets have to be looked up for the specific instant, not the zone in general, because daylight saving changes them twice a year.
Why does the difference between two cities change during the year?
Because they change their clocks on different dates, or one does not change at all. New York and London are usually five hours apart, but for two weeks each spring and one each autumn they are four, because the US switches before the UK.
Does this handle daylight saving time?
Yes. Every conversion is done at a specific instant using the runtime’s time zone database, so the right offset applies on either side of a change, and the results say when a zone is on daylight time.
Where does the time zone data come from?
From the Intl API built into your browser — the same IANA time zone database operating systems use. Nothing is fetched from a server, so it is as current as your browser.
Can I share a conversion?
Yes. The time, source zone and target zones are in the page address, so the link reproduces exactly what you see.