Seoul is on the exact same time as Tokyo year-round (0 hours difference: JST UTC+9 in winter and JST UTC+9 in summer). When it is 9:00 AM in Tokyo, it is 9:00 AM in Seoul. Best meeting window: 9:00 AM – 5:00 PM JST in Tokyo (9:00 AM – 5:00 PM KST in Seoul — Golden 9–5 Overlap).
At the standard 0 hours offset (JST to KST), Tokyo and Seoul share 8 hours/day of simultaneous 9:00 AM – 5:00 PM business hours: 9:00 AM – 5:00 PM JST in Tokyo equals 9:00 AM – 5:00 PM KST in Seoul.
Both Tokyo (JST) and Seoul (KST) are simultaneously inside 9:00 AM – 5:00 PM core working hours (8h/day year-round).
Covers 10 hours/day when either Tokyo (JST) or Seoul (KST) is outside 7:00 AM – 9:00 PM local time.
Geographically, Tokyo (Japan, 35.68°N, 139.65°E, IATA: HND/NRT) and Seoul (South Korea, 37.57°N, 126.98°E, IATA: ICN) are separated by a great-circle distance of 1,149 km (714 miles, approximately 2h non-stop flight). By longitude, true solar time in Seoul is 51 minutes behind Tokyo (a 51-minute divergence from the 0 hours standard civil clock offset): Tokyo (35.68°N, 139.65°E) sits 4.65° east of the 135.0°E JST reference meridian, so mean solar noon occurs at 11:41 AM JST year-round, while Seoul (37.57°N, 126.98°E) sits 8.02° west of the 135.0°E KST reference meridian, so mean solar noon occurs at 12:32 PM KST year-round.
| Tokyo Time | Seoul (Standard (JST → KST)) | Day Shift | Call Status |
|---|---|---|---|
| 9:00 AM JST (Morning Start) | 9:00 AM KST | Same day | Working Overlap (9–5) |
| 12:00 PM JST (Midday / Noon) | 12:00 PM KST | Same day | Working Overlap (9–5) |
| 3:00 PM JST (Afternoon) | 3:00 PM KST | Same day | Working Overlap (9–5) |
| 6:00 PM JST (Evening Wrap-up) | 6:00 PM KST | Same day | Shoulder Hours |
| Tokyo (JST) | Seoul (Standard (JST → KST)) | Day (Seoul) | Availability (Tokyo ↔ Seoul) |
|---|---|---|---|
| 12:00 AM JST in Tokyo | 12:00 AM KST in Seoul | Same day | Tokyo–Seoul Overnight |
| 1:00 AM JST in Tokyo | 1:00 AM KST in Seoul | Same day | Tokyo–Seoul Overnight |
| 2:00 AM JST in Tokyo | 2:00 AM KST in Seoul | Same day | Tokyo–Seoul Overnight |
| 3:00 AM JST in Tokyo | 3:00 AM KST in Seoul | Same day | Tokyo–Seoul Overnight |
| 4:00 AM JST in Tokyo | 4:00 AM KST in Seoul | Same day | Tokyo–Seoul Overnight |
| 5:00 AM JST in Tokyo | 5:00 AM KST in Seoul | Same day | Tokyo–Seoul Overnight |
| 6:00 AM JST in Tokyo | 6:00 AM KST in Seoul | Same day | Tokyo–Seoul Overnight |
| 7:00 AM JST in Tokyo | 7:00 AM KST in Seoul | Same day | Tokyo–Seoul Shoulder |
| 8:00 AM JST in Tokyo | 8:00 AM KST in Seoul | Same day | Tokyo–Seoul Shoulder |
| 9:00 AM JST in Tokyo | 9:00 AM KST in Seoul | Same day | Tokyo–Seoul 9–5 |
| 10:00 AM JST in Tokyo | 10:00 AM KST in Seoul | Same day | Tokyo–Seoul 9–5 |
| 11:00 AM JST in Tokyo | 11:00 AM KST in Seoul | Same day | Tokyo–Seoul 9–5 |
| 12:00 PM JST in Tokyo | 12:00 PM KST in Seoul | Same day | Tokyo–Seoul 9–5 |
| 1:00 PM JST in Tokyo | 1:00 PM KST in Seoul | Same day | Tokyo–Seoul 9–5 |
| 2:00 PM JST in Tokyo | 2:00 PM KST in Seoul | Same day | Tokyo–Seoul 9–5 |
| 3:00 PM JST in Tokyo | 3:00 PM KST in Seoul | Same day | Tokyo–Seoul 9–5 |
| 4:00 PM JST in Tokyo | 4:00 PM KST in Seoul | Same day | Tokyo–Seoul 9–5 |
| 5:00 PM JST in Tokyo | 5:00 PM KST in Seoul | Same day | Tokyo–Seoul Shoulder |
| 6:00 PM JST in Tokyo | 6:00 PM KST in Seoul | Same day | Tokyo–Seoul Shoulder |
| 7:00 PM JST in Tokyo | 7:00 PM KST in Seoul | Same day | Tokyo–Seoul Shoulder |
| 8:00 PM JST in Tokyo | 8:00 PM KST in Seoul | Same day | Tokyo–Seoul Shoulder |
| 9:00 PM JST in Tokyo | 9:00 PM KST in Seoul | Same day | Tokyo–Seoul Late evening / night |
| 10:00 PM JST in Tokyo | 10:00 PM KST in Seoul | Same day | Tokyo–Seoul Late evening / night |
| 11:00 PM JST in Tokyo | 11:00 PM KST in Seoul | Same day | Tokyo–Seoul Late evening / night |
Neither Tokyo (JST, UTC+9, Asia/Tokyo) nor Seoul (KST, UTC+9, Asia/Seoul) observes Daylight Saving Time. Across all 12 months, Seoul remains 0 hours the same time as Tokyo.
No Daylight Saving Time observed. Remains on JST (UTC+9) year-round.
No Daylight Saving Time observed. Remains on KST (UTC+9) year-round.
Tokyo and Seoul have a 0-hour time difference year-round, sharing JST (UTC+9) in winter and JST (UTC+9) in summer.
Yes — 4:00 PM JST in Tokyo is 4:00 PM KST (same day) in Seoul, which is inside standard 9:00 AM – 5:00 PM business hours in both cities.
Aim for 9:00 AM – 5:00 PM JST in Tokyo, which is 9:00 AM – 5:00 PM KST in Seoul (8h/day of 9–5 overlap). Avoid calling between 9:00 PM – 7:00 AM JST (+1 day) in Tokyo (9:00 PM – 7:00 AM KST (+1 day) in Seoul), when at least one city is outside 7:00 AM – 9:00 PM.
Neither Tokyo (Asia/Tokyo) nor Seoul (Asia/Seoul) observes Daylight Saving Time, so the 0 hours offset never changes.
Year-round under standard alignment, 9:00 AM in Tokyo is 9:00 AM KST in Seoul, and 12:00 PM (noon) in Tokyo is 12:00 PM KST in Seoul.