Seoul is 9 hours ahead of London in winter (GMT UTC+0 → KST UTC+9) and 8 hours ahead in summer (BST UTC+1 → KST UTC+9). A 9:00 AM start in London is 6:00 PM KST in winter and 5:00 PM KST in summer in Seoul. Best meeting window — Winter (GMT): 9:00 AM – 12:00 PM GMT (6:00 PM – 9:00 PM KST); Summer (BST): 8:30 AM – 11:30 AM BST (4:30 PM – 7:30 PM KST).
With a 9 hours gap in Winter (GMT) (GMT → KST) and a 8 hours gap in Summer (BST) (BST → KST), London and Seoul have 0 hours of simultaneous 9:00 AM – 5:00 PM business hours in either season. Meetings use morning and early-evening shoulder windows within 7:00 AM – 9:00 PM local time.
Optimal London–Seoul shoulder bridge for Winter (GMT) (9 hours gap) and Summer (BST) (8 hours gap), ending at or before 9:00 PM local time.
Covers every hour where London or Seoul is outside 7:00 AM – 9:00 PM local time (19h/day in Winter (GMT); 18h/day in Summer (BST)).
| London Time | Seoul (Winter (GMT → KST)) | Day Shift | Seoul (Summer (BST → KST)) | Call Status |
|---|---|---|---|---|
| 9:00 AM GMT (Morning Start) | 6:00 PM KST | Same day | 5:00 PM KST | Shoulder Hours |
| 12:00 PM GMT (Midday / Noon) | 9:00 PM KST | Same day | 8:00 PM KST | Late evening / night |
| 3:00 PM GMT (Afternoon) | 12:00 AM KST (+1 day) | +1 day | 11:00 PM KST | Overnight / Rest |
| 6:00 PM GMT (Evening Wrap-up) | 3:00 AM KST (+1 day) | +1 day | 2:00 AM KST (+1 day) | Overnight / Rest |
| London (GMT) | Seoul (Winter (GMT → KST)) | Day (Seoul) | Seoul (Summer (BST → KST)) | Availability (London ↔ Seoul) |
|---|---|---|---|---|
| 12:00 AM GMT in London | 9:00 AM KST in Seoul | Same day | 8:00 AM KST | London–Seoul Overnight |
| 1:00 AM GMT in London | 10:00 AM KST in Seoul | Same day | 9:00 AM KST | London–Seoul Overnight |
| 2:00 AM GMT in London | 11:00 AM KST in Seoul | Same day | 10:00 AM KST | London–Seoul Overnight |
| 3:00 AM GMT in London | 12:00 PM KST in Seoul | Same day | 11:00 AM KST | London–Seoul Overnight |
| 4:00 AM GMT in London | 1:00 PM KST in Seoul | Same day | 12:00 PM KST | London–Seoul Overnight |
| 5:00 AM GMT in London | 2:00 PM KST in Seoul | Same day | 1:00 PM KST | London–Seoul Overnight |
| 6:00 AM GMT in London | 3:00 PM KST in Seoul | Same day | 2:00 PM KST | London–Seoul Overnight |
| 7:00 AM GMT in London | 4:00 PM KST in Seoul | Same day | 3:00 PM KST | London–Seoul Shoulder |
| 8:00 AM GMT in London | 5:00 PM KST in Seoul | Same day | 4:00 PM KST | London–Seoul Shoulder |
| 9:00 AM GMT in London | 6:00 PM KST in Seoul | Same day | 5:00 PM KST | London–Seoul Shoulder |
| 10:00 AM GMT in London | 7:00 PM KST in Seoul | Same day | 6:00 PM KST | London–Seoul Shoulder |
| 11:00 AM GMT in London | 8:00 PM KST in Seoul | Same day | 7:00 PM KST | London–Seoul Shoulder |
| 12:00 PM GMT in London | 9:00 PM KST in Seoul | Same day | 8:00 PM KST | London–Seoul Late evening / night |
| 1:00 PM GMT in London | 10:00 PM KST in Seoul | Same day | 9:00 PM KST | London–Seoul Late evening / night |
| 2:00 PM GMT in London | 11:00 PM KST in Seoul | Same day | 10:00 PM KST | London–Seoul Late evening / night |
| 3:00 PM GMT in London | 12:00 AM KST in Seoul | +1 day | 11:00 PM KST | London–Seoul Overnight |
| 4:00 PM GMT in London | 1:00 AM KST in Seoul | +1 day | 12:00 AM KST (+1 day) | London–Seoul Overnight |
| 5:00 PM GMT in London | 2:00 AM KST in Seoul | +1 day | 1:00 AM KST (+1 day) | London–Seoul Overnight |
| 6:00 PM GMT in London | 3:00 AM KST in Seoul | +1 day | 2:00 AM KST (+1 day) | London–Seoul Overnight |
| 7:00 PM GMT in London | 4:00 AM KST in Seoul | +1 day | 3:00 AM KST (+1 day) | London–Seoul Overnight |
| 8:00 PM GMT in London | 5:00 AM KST in Seoul | +1 day | 4:00 AM KST (+1 day) | London–Seoul Overnight |
| 9:00 PM GMT in London | 6:00 AM KST in Seoul | +1 day | 5:00 AM KST (+1 day) | London–Seoul Overnight |
| 10:00 PM GMT in London | 7:00 AM KST in Seoul | +1 day | 6:00 AM KST (+1 day) | London–Seoul Late evening / night |
| 11:00 PM GMT in London | 8:00 AM KST in Seoul | +1 day | 7:00 AM KST (+1 day) | London–Seoul Late evening / night |
Between London (United Kingdom, Europe/London) and Seoul (South Korea, Asia/Seoul), the seasonal offset shifts by 1 hour. In winter standard time (GMT vs. KST), Seoul (UTC+9) is 9 hours ahead of London (UTC+0). In summer (BST vs. KST), Seoul (UTC+9) is 8 hours ahead of London (UTC+1).
No Daylight Saving Time observed. Remains on KST (UTC+9) year-round.
| Date Window | Duration | Active Zones | Time Difference | Regime |
|---|---|---|---|---|
| Since Oct 25, 2026 | 154 days | GMT (UTC+0) → KST (UTC+9) | 9 hours | Standard Alignment (Active Now) |
| Mar 28, 2027 – Oct 31, 2027 | 217 days | BST (UTC+1) → KST (UTC+9) | 8 hours | Standard Alignment |
| Oct 31, 2027 – Nov 3, 2027 | 3 days | GMT (UTC+0) → KST (UTC+9) | 9 hours | Standard Alignment |
Because Seoul is 9 hours ahead in winter and 8 hours ahead in summer, Seoul enters the next calendar day (+1 day) at 3:00 PM GMT in winter and 4:00 PM BST in summer in London. Before that cutoff, both locations share the same weekday; from 3:00 PM GMT (4:00 PM BST in summer) until midnight in London, Mon–Fri in London maps to Tue–Sat in Seoul.
Weekend & Workday Alignment: Friday afternoon/evening in London (any slot at or after 3:00 PM GMT / 4:00 PM BST in summer) lands on Saturday morning/afternoon in Seoul—which is Seoul's weekend (Sat–Sun). Conversely, Monday morning in Seoul (before 9:00 AM KST) is still Sunday in London (London's Sat–Sun weekend). For late-day London / morning Seoul syncs, book Monday–Thursday in London (Tuesday–Friday in Seoul).
Geographically, London (United Kingdom, 51.51°N, 0.13°W, IATA: LHR/LGW/STN) and Seoul (South Korea, 37.57°N, 126.98°E, IATA: ICN) are separated by a great-circle distance of 8,857 km (5,503 miles, approximately 11h non-stop flight). By longitude, true solar time in Seoul is 8 hours and 28 minutes ahead of London (a 32-minute divergence from the 9 hours standard civil clock offset): London (51.51°N, 0.13°W) sits 0.13° west of the 0.0°E GMT reference meridian, so mean solar noon occurs at 12:01 PM GMT in winter and 1:01 PM BST in summer, 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.
For London → Seoul: Literal BST (British Summer Time) is UTC+1, active in the UK from the last Sunday of March to the last Sunday of October. In winter, the UK returns to GMT (UTC+0).
| Abbreviation Meaning | UTC Offset | IANA Zone | Major Cities & Regions |
|---|---|---|---|
| British Summer Time Primary Here | UTC+1 (late March – late October) | Europe/London | Active on London → Seoul: London, Manchester, Edinburgh, Belfast |
| Bangladesh Standard Time | UTC+6 (year-round) | Asia/Dhaka | Not used for London → Seoul: Dhaka, Chittagong (Bangladesh) |
In winter (standard time), Seoul (KST, UTC+9) is 9 hours ahead of London (GMT, UTC+0). In summer (daylight saving time), Seoul (KST, UTC+9) is 8 hours ahead of London (BST, UTC+1).
No — 4:00 PM in London is 1:00 AM KST (+1 day) in winter and 12:00 AM KST (+1 day) in summer in Seoul, which is outside the 7:00 AM – 9:00 PM calling window. Book calls during 9:00 AM – 12:00 PM GMT in winter or 8:30 AM – 11:30 AM BST in summer.
In winter (GMT), the best window is 9:00 AM – 12:00 PM GMT in London (6:00 PM – 9:00 PM KST in Seoul). In summer (BST), use 8:30 AM – 11:30 AM BST in London (4:30 PM – 7:30 PM KST in Seoul). Avoid hours outside 7:00 AM – 9:00 PM local time (12:00 PM – 7:00 AM GMT (+1 day) in winter; 1:00 PM – 7:00 AM BST (+1 day) in summer).
London: Sun, Mar 28, 2027 (GMT → BST, new gap: 8 hours (BST UTC+1 vs KST UTC+9)). Seoul: No DST (KST year-round).
In winter (GMT), 9:00 AM London is 6:00 PM KST and 12:00 PM is 9:00 PM KST in Seoul. In summer (BST), 9:00 AM is 5:00 PM KST and 12:00 PM is 8:00 PM KST.