Convert JST to GMT
Compare Japan Standard Time and Greenwich Mean Time with a live converter, hourly table, and tools to plan meetings across UTC+9 and UTC+0.
How JST to GMT Works
Japan Standard Time is UTC+9 and Greenwich Mean Time is UTC+0, so GMT is 9 hours behind JST. Enter any time to convert it instantly between these two standard time zones.
Hour-by-Hour Conversion Table
Use the visual hour-by-hour table to compare JST and GMT across the day. Scan business hours quickly, then export times with ICS download or add them to Google Calendar and Gmail.
Schedule Meetings Accurately
Find overlapping hours for Japan Standard Time and Greenwich Mean Time and avoid off-hour meetings. The converter tracks timezone rules and historical changes using the IANA timezone database for accurate automatic adjustment.
How to Convert JST to GMT
Open the JST to GMT converter: Go to https://www.xconvert.com/time-converter/jst-to-gmt-converter to see Japan Standard Time and Greenwich Mean Time on a visual comparison grid. This page is useful when you are scheduling a call with colleagues in the United Kingdom, Ireland, Ghana, or Iceland and need to see how a workday in Japan lines up with offices using GMT.
Add comparison cities: Click + Add City and search for cities such as Tokyo, London, and Dublin to compare Japan with major GMT locations used for finance, media, logistics, and cross-border operations. This helps if your team includes Japan-based staff and partners in the United Kingdom or Ireland, or if you are planning support coverage across East Asia and West Africa.
Select a time range on the grid: Click Select, then drag across the colored timeline in the JST row to highlight a working block such as 9:00 to 12:00 JST, which corresponds to 0:00 to 3:00 GMT. You can resize the purple selection with the left and right handles or drag the center to test another slot, such as 15:00 JST = 6:00 GMT or 18:00 JST = 9:00 GMT, to see whether an early Japan afternoon works better for GMT participants.
Export and share the result: After selecting a range, use the export options for ICS download, Google Calendar, Gmail, Copy to clipboard, or Share link. This is practical for sending a confirmed meeting window to a distributed team so a Tokyo-based manager, a London client, and a Dublin operations contact all receive the same slot in their own calendar workflow.
Understanding the JST to GMT Time Difference
Japan Standard Time (JST) is UTC+9, while Greenwich Mean Time (GMT) is UTC+0. That means GMT is 9 hours behind JST, or viewed the other way, JST is 9 hours ahead of GMT. In practical terms, when it is 9:00 JST, it is 0:00 GMT, and when it is 12:00 JST, it is 3:00 GMT.
The same relationship continues through the day: 15:00 JST = 6:00 GMT and 18:00 JST = 9:00 GMT. This makes JST mornings fall in the overnight or very early morning hours for GMT, while late afternoon in Japan lines up with the start of the GMT business morning. For teams coordinating between Japan and GMT locations, this usually pushes live collaboration toward later Japan hours.
Daylight saving time matters here because JST does not observe DST, while GMT is a standard-time abbreviation and its DST counterpart is BST. As a result, the JST-to-GMT difference applies specifically when the other side is on GMT; during months when the United Kingdom and related locations use BST instead of GMT, the label changes and the comparison is no longer a pure JST-to-GMT match. This is especially important for anyone booking meetings with London-based teams, because a winter schedule using GMT will not be labeled the same way in the warmer part of the year.
GMT is used across a wide geographic spread that includes the United Kingdom, Ireland, Iceland, Ghana, Senegal, Sierra Leone, Liberia, Mali, Guinea, Guinea-Bissau, Gambia, Togo, Burkina Faso, Mauritania, Sao Tome and Principe, Saint Helena, Jersey, Guernsey, and the Isle of Man. That means a JST to GMT conversion is relevant not only for UK business calls, but also for trade, shipping, nonprofit coordination, aviation planning, and remote support coverage involving West Africa and North Atlantic locations.
Best Times for Calls and Meetings Between JST and GMT
Because GMT is 9 hours behind JST, the overlap between normal office hours is limited and tends to favor late afternoon or early evening in Japan with early morning in GMT. The clearest examples are 15:00 JST = 6:00 GMT and 18:00 JST = 9:00 GMT. For many teams, 18:00 JST / 9:00 GMT is the more practical anchor because it places the GMT side at the start of the workday instead of before standard office hours.
A 9:00 JST = 0:00 GMT conversion is rarely suitable for live meetings unless the GMT participant is working a night shift, handling urgent operations, or covering a global incident response window. Likewise, 12:00 JST = 3:00 GMT is usually too early for standard business calls in London, Dublin, or Accra. These early conversions are more useful for asynchronous planning, handoff notes, or scheduling messages to arrive before the GMT workday begins.
For recurring meetings, a late-Japan slot often works best for companies with engineering, manufacturing, gaming, automotive, and electronics teams in Japan that need morning input from GMT-based legal, finance, publishing, or operations staff. A Tokyo team can keep its core workday uninterrupted and then use the end of the day for external coordination, while GMT participants join after starting their morning. This structure is common when Japanese headquarters coordinate with UK partners, Ireland-based support teams, or organizations operating across GMT countries in West Africa.
If your goal is to maximize attendance, use the grid to compare a few candidate windows around the sample points already established on the page. Starting from 15:00 JST = 6:00 GMT and moving the selection toward 18:00 JST = 9:00 GMT helps you test whether the meeting should prioritize convenience for Japan, convenience for GMT, or a balanced compromise for both sides.
Frequently Asked Questions
What is the time difference between JST and GMT?
The time difference is 9 hours. JST is 9 hours ahead of GMT, and equivalently GMT is 9 hours behind JST. This means a daytime hour in Japan often maps to the same calendar day's early morning in GMT.
When is 9 AM JST in GMT?
9:00 JST = 0:00 GMT. This places 9 AM in Japan at midnight in GMT, which is usually outside normal business hours for GMT-based participants. It is more suitable for overnight operations, automated processes, or sending updates that will be seen first thing in the GMT morning.
When is 12 PM JST in GMT?
12:00 JST = 3:00 GMT. A noon meeting in Japan lands at 3 AM in GMT, so it is generally not practical for standard office collaboration. This conversion is more useful for understanding overnight processing windows, publication timing, or support handoffs rather than live meetings.
When is 3 PM JST in GMT?
15:00 JST = 6:00 GMT. This is one of the first points in the day where a JST-to-GMT meeting starts to become workable for early-rising GMT participants, especially in industries that begin operations early such as logistics, news, aviation, or market monitoring. It can also serve as a pre-work check-in for GMT teams before their full business day begins.
When is 6 PM JST in GMT?
18:00 JST = 9:00 GMT. This is typically the strongest meeting option from the sample conversions because it aligns with the beginning of a normal GMT workday while remaining possible for Japan-based teams at the end of their day. It works well for project reviews, account management calls, and cross-border status meetings.
Does the difference between JST and GMT change during DST?
The JST to GMT difference itself is 9 hours, and JST does not observe DST. However, GMT is a standard-time abbreviation, and its daylight saving counterpart is BST, so schedules involving the United Kingdom and related locations may use a different time label during DST months. That means anyone arranging recurring meetings with London-based contacts should pay attention to whether the other side is currently using GMT or BST.
What is the best meeting time between JST and GMT?
The best meeting time usually falls in the late afternoon or early evening in Japan and the early morning in GMT. Among the listed examples, 18:00 JST = 9:00 GMT is the most practical for standard business use because it avoids midnight and pre-dawn hours on the GMT side. If the GMT participant can start earlier than usual, 15:00 JST = 6:00 GMT may also work for time-sensitive coordination.
Which countries use JST and GMT?
JST is used in Japan. GMT is used in Burkina Faso, Gambia, Ghana, Guernsey, Guinea, Guinea-Bissau, Iceland, Ireland, Isle of Man, Ivory Coast, Jersey, Liberia, Mali, Mauritania, Saint Helena, Sao Tome and Principe, Senegal, Sierra Leone, Togo, and the United Kingdom. This makes JST-to-GMT conversion useful for everything from Japan-UK business communication to nonprofit, government, shipping, and remote team coordination across multiple regions.