Asia/Seoul time zone

What is the Asia/Seoul zone?

Asia/Seoul is one of the canonical IANA time zone identifiers. It currently sits at UTC+09:00 from Coordinated Universal Time, with the abbreviation KST. The zone does not currently observe daylight saving time, so the offset above is stable year-round (subject only to occasional political changes recorded in the IANA database).

For scheduling purposes, the most important property of an IANA zone is that it represents not just an offset but a set of historical and future transition rules. Two cities can sit at the same offset right now and yet be in different IANA zones because their governments make different decisions about daylight saving or because their offsets diverged in the past. ZoneShift always uses the IANA identifier as the source of truth.

Cities in this zone

City	Country	Population	Local time
Seoul	South Korea	10.3M	05:06, Fri
Busan	South Korea	3.3M	05:06, Fri
Incheon	South Korea	3.0M	05:06, Fri
Daegu	South Korea	2.4M	05:06, Fri
Daejeon	South Korea	1.4M	05:06, Fri
Gwangju	South Korea	1.4M	05:06, Fri
Suwon	South Korea	1.2M	05:06, Fri
Ulsan	South Korea	1.1M	05:06, Fri
Goyang-si	South Korea	1.1M	05:06, Fri
Changwon	South Korea	1.0M	05:06, Fri

Tips for working with this zone

If you have several teammates in the cities listed above, treat them as a single working group from a scheduling point of view: any meeting that suits one of them suits all of them, because they all roll over to the same wall-clock time. A 10:00 standup in Seoul is also 10:00 in every other city in the table above, today and any other day of the year.

When you collaborate across zones, always quote times in either the IANA identifier or in UTC, never in the local abbreviation alone. The string "10:00 KST" is ambiguous in a calendar invite — the same letters can refer to other zones, and the abbreviation also changes when daylight saving begins. The unambiguous form is "10:00 (Asia/Seoul)" or "11:06 UTC".