Japan Standard Time (jst) is used in Japan. The IANA timezone identifier is Asia/Tokyo.

Korea Standard Time (kst) is used in South Korea. The IANA timezone identifier is Asia/Seoul.

JST to KST Time Converter

Japan Standard Time → Korea Standard Time

JST = UTC+9KST = UTC+9

ClockinSync

BASE

09:00

Work Clients Team +

00:0006:0012:0018:0024:00

KST (Seoul)

South Korea · UTC±0

09:00

London

United Kingdom · -8h

01:00

New York

USA · -13h

20:00-1 day

Dubai

United Arab Emirates · -5h

04:00

Sydney

Australia · +1h

10:00

JST (Tokyo) ↔ KST (Seoul) — time offset

JST (Tokyo) and KST (Seoul) are in the same timezone. When it's noon in JST (Tokyo), it's 12:00 in KST (Seoul).

JST (Tokyo) observes Asia/Tokyo and KST (Seoul) observes Asia/Seoul — a 0 hours gap between them.

Mutual working hours

Both JST (Tokyo) and KST (Seoul) are simultaneously in business hours for 8 hours per day (assuming standard 9:00–17:00 working hours).

00:0006:0012:0018:0024:00

JST (Tokyo)

KST (Seoul)

Overlap (8h)

Meeting time recommendations

JST (Tokyo) and KST (Seoul) share 8 hours of business hours overlap daily. Showing the 3 most balanced slots — see the time table below for the full window.

09:00 Tokyo / 09:00 Seoul✓ Both working

10:00 Tokyo / 10:00 Seoul✓ Both working

11:00 Tokyo / 11:00 Seoul✓ Both working

Assumes a standard 9 AM–5 PM workday in each location's local timezone.

Public holidays this year

⚡ Upcoming holidays in both locations, confirm with your contact before booking.

JST (Tokyo)7 holidays

Jul 20Marine Day

Aug 11Mountain Day

Sep 21Respect for the Aged Day

Sep 23Autumnal Equinox Day

Oct 12Sports Day

KST (Seoul)7 holidays

Aug 15Liberation Day

Sep 24Chuseok

Sep 25Chuseok

Sep 26Chuseok

Oct 3National Foundation Day

JST (Tokyo) and KST (Seoul) — practical scheduling

Teams in JST (Tokyo) (Japan) and KST (Seoul) (South Korea) face a 0-hour time difference day to day. A 8-hour shared business hours window makes real-time meetings feasible for both sides within their normal working day.

💡 Practical scheduling guidelines

✅

Schedule at 09:00–10:00 (JST (Tokyo)) for a 09:00–10:00 slot in KST (Seoul) — the sweet spot where both teams are working.

✅

Schedule at 10:00–11:00 (JST (Tokyo)) for a 10:00–11:00 slot in KST (Seoul) — the sweet spot where both teams are working.

✅

Schedule at 11:00–12:00 (JST (Tokyo)) for a 11:00–12:00 slot in KST (Seoul) — the sweet spot where both teams are working.

Recurring meetings are particularly vulnerable to DST shifts. The ClockinSync Chrome Extension alerts you before the offset changes.

Install ClockinSync Free →

Drag the slider at the top to convert any JST (Tokyo) time instantly. You can also type natural language like "3pm", "15:00", or a location name to get an immediate answer.

JST (Tokyo) ↔ KST (Seoul)

8h of business hours overlap daily (09:00–17:00)

JST (Tokyo)

KST (Seoul)

00:00

01:00

02:00

03:00

04:00

05:00

06:00

07:00

08:00

09:00Working

10:00Working

11:00Working

12:00Working

13:00Working

14:00Working

15:00Working

16:00Working

17:00

18:00

19:00

20:00

21:00

22:00

23:00

Working hours: 09:00–17:00 local. Green = both working. Purple = one side only.

Frequently Asked Questions

What is the difference between jst and kst?

Japan Standard Time (jst) is UTC+9 and Korea Standard Time (kst) is UTC+9. The difference between them is 0 hours.

Where is jst used?

Japan Standard Time (jst) is used in Japan and surrounding regions. The IANA timezone identifier is Asia/Tokyo.

Where is kst used?

Korea Standard Time (kst) is used in South Korea and surrounding regions. The IANA timezone identifier is Asia/Seoul.

How do I convert jst to kst?

Use the interactive converter above. Drag the time slider to any jst time and the kst equivalent updates instantly. You can also type a time like "3pm" or "15:00" in the input bar.

Popular JST conversions

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Popular KST conversions

London → KST New York → KST Tokyo → KST Dubai → KST Sydney → KST Paris → KST Berlin → KST Singapore → KST Los Angeles → KST Toronto → KST