Time Difference: Seongnam vs London

Seongnam (GMT+9) · London (GMT+1)

Seongnam

GMT+9

--:--:--

London

GMT+1

--:--:--

London and Seongnam are in the same UTC offset

Time Difference

Seongnam Offset

GMT+9

Asia/Seoul

London Offset

GMT+1

Europe/London

Summary

Seongnam and London share the same UTC offset

Business Hours Overlap (9 AM – 6 PM)

9 hours overlap during standard business hours in both cities.

Seongnam	London	Overlap
9 AM	9 AM	Business hours
10 AM	10 AM	Business hours
11 AM	11 AM	Business hours
12 PM	12 PM	Business hours
1 PM	1 PM	Business hours
2 PM	2 PM	Business hours
3 PM	3 PM	Business hours
4 PM	4 PM	Business hours
5 PM	5 PM	Business hours
6 PM	6 PM	Outside

Did You Know? — Seongnam & London

Time Zone Facts: Seongnam

•Uses Seoul timezone in Asia
•Key Asian business hours reference point
•Mid-latitude: Seongnam experiences pronounced seasons with 9–15 hours daylight variation

Time Zone Facts: London

•London sits on the Prime Meridian at 0° longitude, which is why Greenwich Mean Time (GMT/UTC+0) became the world's reference timezone in 1884 at the International Meridian Conference.
•The London Stock Exchange opens at 8:00 AM GMT and closes at 4:30 PM GMT, making London's morning the global overlap window where both European and (briefly) US pre-market traders are active.
•At 51.5°N — further north than most of Canada — London receives only about 7.5 hours of daylight at winter solstice but enjoys over 16.5 hours of daylight in midsummer.

Frequently Asked Questions

Seongnam and London are in the same time zone offset, so there is no time difference between them.

There are 9 overlapping business hours (9 AM–6 PM) between Seongnam and London. Scheduling during those hours ensures both parties are in their working day.

Seongnam and London share the same UTC offset (GMT+9), so their workdays are completely synchronized — no conversion needed, identical real-time availability, and deadline alignment is automatic.

Seongnam observes GMT+9 (Asia/Seoul). A standard 9:00 AM–6:00 PM workday in Seongnam maps to specific UTC hours — use UTC-anchored deadlines when coordinating with Seongnam-based teammates to avoid confusion from local clock changes.

London observes GMT+1 (Europe/London). A standard 9:00 AM–6:00 PM workday in London maps to specific UTC hours — use UTC-anchored deadlines when coordinating with London-based teammates to avoid confusion from local clock changes.

If {cityA} and {cityB} follow different DST schedules — common in North America–Europe, Southern Hemisphere, or no-DST pairings — the time difference shifts by 1 hour during each transition. The 1–3 weeks between the two cities' clock-change dates create a 'gap window' that frequently catches teams off guard. The difference displayed here is always live and accounts for current DST status.

The best time to call London from Seongnam is during the 9-hour business-hours overlap window, when both cities are within their standard working day (9 AM–6 PM).

When it is midnight (00:00) in Seongnam, it is 12 AM in London.

No — Seongnam and London share the same UTC offset, so they are always on the same calendar date.

Seongnam observes Asia/Seoul (GMT+9). For async-first teams, the most reliable approach is anchoring shared deadlines in UTC rather than any local time, and defining each member's 'availability window' — typically 9:00 AM–6:00 PM Asia/Seoul for Seongnam. This eliminates confusion when DST transitions shift local clocks seasonally.

London observes Europe/London (GMT+1). For async-first teams, the most reliable approach is anchoring shared deadlines in UTC rather than any local time, and defining each member's 'availability window' — typically 9:00 AM–6:00 PM Europe/London for London. This eliminates confusion when DST transitions shift local clocks seasonally.

Yes — with 9 hours of overlapping business hours, Seongnam and London teams can hold real-time standups and synchronous collaboration daily during that window.