JST to GMT Time Converter
GMT is 8 hours behind JST. JST is UTC+9:00, and The UK and Ireland are currently on BST (UTC+1:00).
Best Time to Call Between JST and GMT
Standard 9-to-5 hours in these two zones never overlap, so someone has to take the call outside their working day. The most workable window is 3:00 PM to 10:00 PM JST, which is 7:00 AM to 2:00 PM GMT.
both at work JST only GMT only neither — hours along the strip are JST.
Common Times Converted
JST on the left, GMT on the right.
JST to GMT: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| JST | GMT | Working hours |
|---|---|---|
| 12:00 AM | 4:00 PM prev day | GMT only |
| 1:00 AM | 5:00 PM prev day | — |
| 2:00 AM | 6:00 PM prev day | — |
| 3:00 AM | 7:00 PM prev day | — |
| 4:00 AM | 8:00 PM prev day | — |
| 5:00 AM | 9:00 PM prev day | — |
| 6:00 AM | 10:00 PM prev day | — |
| 7:00 AM | 11:00 PM prev day | — |
| 8:00 AM | 12:00 AM | — |
| 9:00 AM | 1:00 AM | JST only |
| 10:00 AM | 2:00 AM | JST only |
| 11:00 AM | 3:00 AM | JST only |
| 12:00 PM | 4:00 AM | JST only |
| 1:00 PM | 5:00 AM | JST only |
| 2:00 PM | 6:00 AM | JST only |
| 3:00 PM | 7:00 AM | JST only |
| 4:00 PM | 8:00 AM | JST only |
| 5:00 PM | 9:00 AM | GMT only |
| 6:00 PM | 10:00 AM | GMT only |
| 7:00 PM | 11:00 AM | GMT only |
| 8:00 PM | 12:00 PM | GMT only |
| 9:00 PM | 1:00 PM | GMT only |
| 10:00 PM | 2:00 PM | GMT only |
| 11:00 PM | 3:00 PM | GMT only |
What JST and GMT Actually Are
JST — Japan Standard Time
Tokyo, Osaka, Yokohama, Nagoya, Sapporo. Standing at UTC+9:00 as written, and the region does not change its clocks, so that offset holds all year. Japan does not observe daylight saving, so this offset is fixed year-round.
Japan abolished daylight saving in 1952 and has resisted every attempt to reintroduce it, including a proposal around the 2020 Olympics.
GMT — Greenwich Mean Time
The UK and Ireland in winter, plus Iceland, Portugal and much of West Africa. Standing at UTC as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, October 25, 2026, to GMT. Often used loosely as a synonym for UTC. They differ by less than a second, so for scheduling they are interchangeable.
Britain ran an experiment from 1968 to 1971 on permanent UTC+1, abandoning GMT entirely. It was scrapped after complaints about dark winter mornings in Scotland.
What This Means in Practice
This gap is not fixed
GMT changes its clocks and JST does not, so the difference between them moves by an hour twice a year. A recurring meeting set now will drift for one side from Sunday, October 25, 2026 unless someone resets it.
Major Cities in Each Zone
Cities on JST
Cities on GMT
Frequently Asked Questions
What is the time difference between JST and GMT?
GMT is 8 hours behind JST. That is the live figure. Taken strictly as written, the gap between JST and GMT is 9 hours — the two differ because at least one of these regions is currently on daylight saving.
What is 9:00 AM JST in GMT?
9:00 AM JST is 1:00 AM GMT.
What are the best hours to schedule a call between JST and GMT?
Standard business hours in these two zones do not overlap at all, so one side has to work outside the 9-to-5. The most workable window is 3:00 PM to 10:00 PM JST, which is 7:00 AM to 2:00 PM GMT.
Does the difference between JST and GMT change during the year?
Yes. GMT observes daylight saving and JST does not, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, October 25, 2026.
Does JST always mean Japan Standard Time?
Japan does not observe daylight saving, so this offset is fixed year-round.
Does GMT always mean Greenwich Mean Time?
Often used loosely as a synonym for UTC. They differ by less than a second, so for scheduling they are interchangeable.