KST to UTC Converter (Korea Time to Coordinated Universal Time)

UTC is 9 hours behind KST.

To turn a Korean time into UTC, subtract nine hours. Korea Standard Time is UTC+9 and does not change with the seasons, so the same rule works in January and in July. When the subtraction goes below zero, add 24 hours and move back one calendar day.

Developers, analysts, game operators and international coordinators use this direction when a Korean schedule has to be written in universal time. A maintenance window quoted as 02:00 to 05:00 KST is 17:00 to 20:00 UTC on the day before.

How to use this tool

1. Pick a date and time in KST. The date matters when daylight saving time is in force.
2. Read the matching time in UTC, with both UTC offsets.
3. Use "Use current time" for now, or the tables below for a quick look.

Formula

UTC time = KST time − (KST UTC offset) + (UTC UTC offset)

The converter looks up both UTC offsets for the actual instant in the saved IANA time zone rules, so daylight saving changes are included automatically.

Example

Worked with the saved rules:

9:00 AM KST on March 2, 2026 = 12:00 AM UTC

6:30 PM KST on August 3, 2026 = 9:30 AM UTC

Time difference through the year

The difference depends on the date when either place moves its clocks. These are the offsets on two reference days, from the saved IANA rules:

Clock changes in 2026

Korea Standard Time and Coordinated Universal Time do not change clocks in this year, so the difference stays the same all year.

KST to UTC time table

Each hour in Korea Standard Time with the matching Coordinated Universal Time time.

UTC to KST time table

Each hour in Coordinated Universal Time with the matching Korea Standard Time time.

Hours that work in both places

Hours (on the January reference day) that fall between 8:00 AM and 8:00 PM in both KST and UTC:

The date boundary falls at 9 a.m. in Seoul

Between midnight and 9:00 a.m. in Seoul, the UTC date is still the previous one. A record created at 8:59 a.m. on March 2 in Seoul is stamped March 1 in UTC, and one created at 9:00 a.m. is stamped March 2.

This is the usual cause of a Korean report that seems to be missing its first morning: a query set to "yesterday" in UTC cuts the Korean day nine hours after its start. Convert the boundaries rather than the dates.

Writing times for an international audience

When you publish a Korean event for people abroad, give the time in both KST and UTC and avoid expressions such as "Korea time" alone. Readers in other countries can then compute their own hour without asking which zone you meant.

Unix timestamps are counts of seconds since a UTC epoch and carry no zone at all, so a program does not need to subtract nine hours internally. The subtraction belongs to display, and the stored time should stay in UTC.