JST ↔ GMT Time Converter

Greenwich Mean Time (GMT) is 9h behind of Japan Standard Time (JST). This comes from JST being at UTC+9 and GMT at UTC+0 / UTC+1 (BST). Three quick examples: 9:00 AM JST = 12:00 AM GMT; 12:00 PM JST = 3:00 AM GMT; 5:00 PM JST = 8:00 AM GMT.

To convert JST to GMT, subtract 9 hours to the JST time. For example: 12:00 PM JST → 3:00 AM GMT. When the result goes past midnight, increment the date by one day (shown as "+1 Day" in the converter). The converter on this page handles all edge cases automatically.

Greenwich Mean Time (GMT) is 9h behind of Japan Standard Time (JST). The reverse is also true: JST is 9h ahead of GMT. A real-world example: if a colleague in London proposes a noon meeting, that means 9:00 PM on your JST clock in Tokyo.

Japan Standard Time (JST) is the standard civil time used across Tokyo, Osaka, Kyoto, Yokohama and surrounding regions. It sits at UTC+9 relative to UTC. It does not observe Daylight Saving Time, so the UTC offset remains constant at UTC+9 every day of the year. Major cities in this zone include: Tokyo, Osaka, Kyoto, Yokohama, Nagoya, Sapporo, Fukuoka.

Greenwich Mean Time (GMT) is the civil time standard for London, Dublin, Lisbon, Reykjavik and the surrounding area. Operating at UTC+0 / UTC+1 (BST) from UTC, it observes Daylight Saving Time and shifts its clocks seasonally by one hour. Cities in this zone include: London, Dublin, Lisbon, Reykjavik, Accra, Abidjan, Dakar.

Yes, partially. GMT observes Daylight Saving Time and shifts its clocks by one hour during summer, while JST stays fixed at UTC+9 year-round. The gap between the two zones therefore changes seasonally — it shifts by one hour when GMT enters or exits its DST window. The live converter on this page adjusts automatically for the current date.

The best meeting window is where standard working hours (9 AM – 6 PM) overlap in both zones. Since GMT is 9h behind of JST, mornings in the earlier zone align with afternoons or evenings in the later zone. As a rule of thumb: 8 AM – 11 AM in the earlier zone usually works for both sides. Check the meeting hours table above for this specific pair's recommended slots, and avoid any time that falls before 7 AM or after 9 PM on either side.

Type any time into the GMT field in the bidirectional converter above — it calculates the JST result instantly and works equally well in both directions. You can also add 9 hours from the GMT time manually to get the JST equivalent. For a dedicated reverse converter, visit: GMT to JST converter ↗.

Yes, several hours in the day will cross midnight when converting between these two zones. When a converted time crosses 11:59 PM, the date advances by one day — shown as "+1 Day" in the converter. When it goes before 12:00 AM, the date moves back — shown as "-1 Day". The 24-hour reference table on this page also flags day changes in the Day column. Always check the date indicator when sending calendar invites or scheduling calls across these two zones.

Japan Standard Time (JST) is the official time standard for: Tokyo, Osaka, Kyoto, Yokohama, Nagoya, Sapporo, Fukuoka. The zone operates at UTC+9, with no seasonal variation. It is one of the most widely used time zones for international business in its region.

Greenwich Mean Time (GMT) covers: London, Dublin, Lisbon, Reykjavik, Accra, Abidjan, Dakar. It runs at UTC+0 / UTC+1 (BST)and observes Daylight Saving Time during part of the year. When coordinating calls between JST and GMT, use the live clocks at the top of this page to see the exact current local time in both zones simultaneously before confirming a meeting time.

No. Japan abolished Daylight Saving Time in 1951 and has not observed it since. Japan Standard Time (JST) remains fixed at UTC+9 throughout the entire year, with no seasonal clock changes. This means the JST–GMT difference is always predictable: the only variable is whether GMT is currently in its DST period — but the JST side never changes. You can rely on the standard 9h behind difference for any fixed recurring meeting time.

Yes. The live clocks at the top update every second so you always see the current time in both zones. The converter handles DST changes automatically, and the 24-hour table gives you a printable reference for the full day. For recurring meetings, pick a slot from the "Best Meeting Hours" table and set your calendar event with the correct IANA timezone (Asia/Tokyo for JST, Europe/London for GMT) so future occurrences self-adjust for any clock changes.