GMT to JST Time Converter

Common Times Converted

GMT on the left, JST on the right.

GMT to JST: Full 24-Hour Conversion Table

Shaded rows are working hours; the darker shade marks the hours when both zones are at work.

What GMT and JST Actually Are

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.

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.

What This Means in Practice

The date changes mid-working-day

For 1 of the eight hours in a normal GMT working day, the equivalent JST time falls on a different calendar date. Anything scheduled in that stretch needs the date checked as well as the time, or a Tuesday call quietly becomes a Wednesday one at the other end.

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 GMT

Cities on JST