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City data by GeoNames (CC BY 4.0). Timezone data from IANA Time Zone Database.

  1. WorldClockTools
  2. Time Zone Converter
  3. JST -> KST

Timezone converter

JST to KST Converter.

JST → KSTGap: +0h8h 9-5 overlap

JST to KST currently uses Japan Time in Asia/Tokyo and Korean Time in Asia/Seoul as the live reference pair. Right now the gap is +0h, and the sections below break that into meeting-time shortcuts, workday overlap, DST changes, and city coverage on both sides.

Last updated Apr 22, 2026. Offset math, DST behavior, and city coverage on both sides are refreshed from the live timezone dataset during the page revalidation window.

Reverse: KST → JST

From

JST

Japan Time

Asia/Tokyo · GMT+9 +09:00

--:--:--

Major markets in this grouping include Tokyo, Yokohama, Osaka, Nagoya.

To

KST

Korean Time

Asia/Seoul · GMT+9 +09:00

--:--:--

Major markets in this grouping include Seoul, Busan, Pyongyang, Incheon.

Scheduling snapshot

Current gap

+0h

JST +09:00 vs KST +09:00

9-to-5 overlap

8h

JST 9:00 AM previous day to 5:00 PM previous day

Representative countries

Japan / South Korea and North Korea

Based on the busiest city and zone usage found in the current dataset.

Pair context

JST and KST currently connect Tokyo and Seoul with a live gap of +0h. Representative coverage on the JST side is anchored by Tokyo, Yokohama, Osaka, and Nagoya, while the KST side is anchored by Seoul, Busan, Pyongyang, and Incheon.

Using a simple 9:00 AM to 5:00 PM workday on both sides, the pair shares about 8 hours of business overlap - roughly JST 9:00 AM previous day to 5:00 PM previous day, which is KST 9:00 AM previous day to 5:00 PM previous day. Most of the workday still lines up, which is helpful for live support, same-day reviews, and straightforward calendar invites.

The live gap is +0h right now, based on Asia/Tokyo at +09:00 and Asia/Seoul at +09:00. Neither reference zone shows an offset change in the next year, so the gap should stay stable.

Market coverage on both sides

On the JST side, the current dataset is anchored by cities such as Tokyo, Japan; Yokohama, Japan; Osaka, Japan; Nagoya, Japan; Sapporo, Japan; Fukuoka, Japan. That makes this page useful for real-world coordination patterns rather than only abstract offset math.

On the KST side, the live reference set includes Seoul, South Korea; Busan, South Korea; Pyongyang, North Korea; Incheon, South Korea; Daegu, South Korea; Daejeon, South Korea. In practice, that means the conversion is tied to recognizable business, travel, and support hubs rather than a single anonymous timezone label.

Country usage on the two sides currently includes Japan for JST and South Korea and North Korea for KST. That country coverage helps explain why some pairs feel like outsourcing, logistics, gaming, finance, or travel-heavy conversions while others are more niche.

Digit-Roll Converter

Adjust the time — digits roll like an odometer. Swap button flips the zones.

FROM
1
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TO
2
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Common meeting times

JST to KST meeting times

Quick conversions for 9 AM, noon, 3 PM, 6 PM, and 9 PM based on today's local calendar.

JSTKSTDay relation
9:00 AM9:00 AMWed, Apr 22same day
12:00 PM12:00 PMWed, Apr 22same day
3:00 PM3:00 PMWed, Apr 22same day
6:00 PM6:00 PMWed, Apr 22same day
9:00 PM9:00 PMWed, Apr 22same day

KST to JST meeting times

Quick conversions for 9 AM, noon, 3 PM, 6 PM, and 9 PM based on today's local calendar.

KSTJSTDay relation
9:00 AM9:00 AMWed, Apr 22same day
12:00 PM12:00 PMWed, Apr 22same day
3:00 PM3:00 PMWed, Apr 22same day
6:00 PM6:00 PMWed, Apr 22same day
9:00 PM9:00 PMWed, Apr 22same day

Operational notes

JST to KST meeting times is easiest to read as a working-day range rather than a single spot conversion. In the current snapshot, 9:00 AM lands at 9:00 AM, while 9:00 PM lands at 9:00 PM, which makes the practical handoff window much easier to scan.

KST to JST meeting times is easiest to read as a working-day range rather than a single spot conversion. In the current snapshot, 9:00 AM lands at 9:00 AM, while 9:00 PM lands at 9:00 PM, which makes the practical handoff window much easier to scan.

Popular hour answers

These direct answers are here for the exact-intent searches people actually use, like “10 AM JST to KST” or “4 PM JST in KST”.

8 AM9 AM10 AM11 AM12 PM1 PM2 PM3 PM4 PM5 PM6 PM9 PM

What is 8 AM JST in KST?

8 AM JST = 8:00 AM KST (08:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 9 AM JST in KST?

9 AM JST = 9:00 AM KST (09:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 10 AM JST in KST?

10 AM JST = 10:00 AM KST (10:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 11 AM JST in KST?

11 AM JST = 11:00 AM KST (11:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 12 PM JST in KST?

12 PM JST = 12:00 PM KST (12:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 1 PM JST in KST?

1 PM JST = 1:00 PM KST (13:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 2 PM JST in KST?

2 PM JST = 2:00 PM KST (14:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 3 PM JST in KST?

3 PM JST = 3:00 PM KST (15:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 4 PM JST in KST?

4 PM JST = 4:00 PM KST (16:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 5 PM JST in KST?

5 PM JST = 5:00 PM KST (17:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 6 PM JST in KST?

6 PM JST = 6:00 PM KST (18:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

What is 9 PM JST in KST?

9 PM JST = 9:00 PM KST (21:00). On today's live calendar that lands on Wed, Apr 22 in KST, which means the answer is a same day conversion rather than a static offset lookup.

Overlap window and DST radar

The live gap is +0h right now, based on Asia/Tokyo at +09:00 and Asia/Seoul at +09:00. Neither reference zone shows an offset change in the next year, so the gap should stay stable.

The most usable workday block right now is about 8 hours: JST 9:00 AM previous day to 5:00 PM previous day, which lines up with KST 9:00 AM previous day to 5:00 PM previous day.

Reference zones

Asia/Tokyo

GMT+9 · +09:00

Asia/Seoul

GMT+9 · +09:00

These are the busiest live references selected from the abbreviation families on this page.

Conversion Table

JSTKST
09:0009:00
10:0010:00
11:0011:00
12:0012:00
13:0013:00
14:0014:00
15:0015:00
16:0016:00
17:0017:00
18:0018:00
19:0019:00
20:0020:00
21:0021:00
22:0022:00
23:0023:00
00:0000:00
01:0001:00
02:0002:00
03:0003:00
04:0004:00
05:0005:00
06:0006:00
07:0007:00
08:0008:00

Top cities using JST

Countries represented here include Japan.

TokyoJapanYokohamaJapanOsakaJapanNagoyaJapanSapporoJapanFukuokaJapanKawasakiJapanKobeJapanKyotoJapanSaitamaJapan

Top cities using KST

Countries represented here include South Korea and North Korea.

SeoulSouth KoreaBusanSouth KoreaPyongyangNorth KoreaIncheonSouth KoreaDaeguSouth KoreaDaejeonSouth KoreaGwangjuSouth KoreaSuwonSouth KoreaUlsanSouth KoreaGoyang-siSouth Korea

FAQ

How many hours is KST ahead of JST?
KST is currently +0h relative to JST, using Asia/Tokyo and Asia/Seoul as the live reference zones on this page.
What is the best workday overlap between JST and KST?
The current 9-to-5 overlap is about 8 hours: JST 9:00 AM previous day to 5:00 PM previous day, which matches KST 9:00 AM previous day to 5:00 PM previous day.
Does the JST-KST time difference change during DST?
The live gap is +0h right now, based on Asia/Tokyo at +09:00 and Asia/Seoul at +09:00. Neither reference zone shows an offset change in the next year, so the gap should stay stable.
Which cities commonly use JST and KST?
JST commonly covers cities such as Tokyo, Yokohama, Osaka, and Nagoya, while KST commonly covers cities such as Seoul, Busan, Pyongyang, and Incheon.
Should I use JST/KST or exact IANA zones?
Use the abbreviations for a quick read, but use exact IANA zones such as Asia/Tokyo and Asia/Seoul when you need something precise in software, travel plans, or long-range scheduling.
Open Interactive Converter

Related Conversions

EST → JSTEST → KSTPST → JSTPST → KSTCST → JSTCST → KSTMST → JSTMST → KSTGMT → JSTGMT → KSTUTC → JSTUTC → KST

Related planning pages

Once a conversion pair matters, people usually need a city page, compare page, or a broader browse surface next.

Interactive converter

Move from this static pair into the full timezone converter with more cities and abbreviations.

Compare city pairs

Use compare pages when the practical question is overlap, not just offset arithmetic.

World clock

Open live city clocks after narrowing the timezone pair you care about.

Browse city pages

Jump into the strongest city pages when you want location-specific timezone context.