JST to GMT Time Converter
Greenwich Mean Time (GMT) is currently 9 hours behind Japan Standard Time (JST). JST is UTC+9 and GMT is UTC+0. The table below converts every hour of the day between the two, and the call planner shows where working hours line up.
Best Time for a Call
There is no overlap between 9:00 AM and 5:00 PM office hours in these two zones. Stretching to early mornings and evenings, the workable window runs from 4:00 PM to 9:00 PM in JST, which is 7:00 AM to 12:00 PM in GMT. One side ends up outside normal hours, so alternating who takes the awkward slot is a fair way to handle recurring calls.
Comparing more than two places? The Overlap Zones tool shows working hours for several cities on one grid.
Hour by Hour: JST to GMT
Rows marked office hours fall between 9:00 AM and 5:00 PM in both places. For a specific date, use the interactive converter.
Does the Difference Change During the Year?
JST and GMT are fixed offsets, so the difference between them never changes.
JST is UTC+9. Japan has no daylight saving, so this offset never changes.
GMT is UTC+0 and never shifts. The UK is on GMT in winter but moves to BST (UTC+1) from late March to late October.
Frequently Asked Questions
How many hours behind is GMT compared to JST?
GMT is currently 9 hours behind JST. JST and GMT are fixed offsets, so the difference between them never changes.
What time is 9:00 AM in JST in GMT?
9:00 AM in JST is 12:00 AM in GMT.
What is the best time for a call between JST and GMT?
There is no overlap between 9:00 AM and 5:00 PM office hours in these two zones. Stretching to early mornings and evenings, the workable window runs from 4:00 PM to 9:00 PM in JST, which is 7:00 AM to 12:00 PM in GMT. One side ends up outside normal hours, so alternating who takes the awkward slot is a fair way to handle recurring calls.