GMT vs JST time zone comparison

How GMT and JST compare

Japan Standard Time runs nine hours ahead of Greenwich Mean Time. London-to-Tokyo is the easiest wide-gap pair to coordinate because the offset creates a clean afternoon-London-to-evening-Tokyo overlap: 9 AM London is 6 PM Tokyo. This is at the very end of the Tokyo working day but still inside reasonable office hours. Push the call to 10 AM London (7 PM Tokyo) and Tokyo is winding down. Earlier than 8 AM London (5 PM Tokyo) and the London side has not yet arrived. The narrow but real shared window is 8-10 AM London (5-7 PM Tokyo), and it is heavily used by global investment banks, consulting firms, and consumer goods companies coordinating Europe-Asia operations. Japan does not observe daylight saving, so the gap shifts from 9 hours in UK winter to 8 hours in UK summer (when the UK is on BST). This makes the same 9 AM London call 6 PM Tokyo in winter and 5 PM Tokyo in summer — slightly more comfortable for Tokyo in summer because it lands during their normal late-afternoon stretch rather than at end-of-day.

Working-hour overlap

Narrow overlap from 8-10 AM London (5-7 PM Tokyo in winter, 4-6 PM Tokyo in summer), with 9 AM London the safest default.

When to schedule

Default to 9 AM London (6 PM Tokyo in winter, 5 PM Tokyo in summer) for cross-zone meetings. The Tokyo side gets the call at end-of-day-stretch, which is workable. For follow-the-sun coordination, London end-of-day (5 PM GMT, 2 AM JST next day) hands off to Tokyo office-open eight hours later. For urgent calls, 8 AM London (5 PM Tokyo in winter) gives Tokyo a fuller working-hour buffer. Avoid afternoon-London schedules entirely; they always land in Tokyo's evening or late night.

Notable context

London (LSE) and Tokyo (TSE) are the two largest non-US financial markets, and the London-Tokyo equity corridor is dominated by Japanese investment in European markets and European exposure to Asian growth. Japanese banks (Mitsubishi UFJ, Mizuho, SMBC) maintain large London branches, and the standard cadence is a 9 AM London status sync with Tokyo head office. Outside finance, Japanese automotive (Toyota, Honda, Nissan) coordinate with European partners on the same window, and Japanese consumer goods (Sony, Panasonic, Uniqlo) run weekly Europe-Asia syncs at 8-9 AM London time.