Convert JST to GMT
See the 9-hour time difference, compare hours side by side, and plan meetings from Japan Standard Time to Greenwich Mean Time.
How JST to GMT Works
JST is UTC+9 and GMT is UTC+0, so GMT is 9 hours behind Japan Standard Time. Enter any time to convert it instantly with the correct offset applied.
Hour-by-Hour Comparison Table
Use the visual grid and hour-by-hour table to compare JST and GMT across the day. Export selected times with ICS download or send them to Google Calendar and Gmail.
Schedule Meetings Accurately
Find overlapping business hours between JST and GMT for calls, events, and deadlines. DST changes are tracked automatically using the IANA timezone database for accurate conversions.
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 load a visual comparison grid with JST and GMT ready for side-by-side viewing. This page is useful when you are scheduling a call between Japan and the United Kingdom, coordinating with partners in Ireland or Ghana, or planning support coverage across teams that work on Japan business hours and GMT business hours.
Add comparison cities if your schedule involves more than one market: Click + Add City and search for cities that matter to your workflow, such as Tokyo for Japan operations and London, Dublin, or Reykjavik for GMT-based coordination. This is especially practical for finance, shipping, gaming, manufacturing, and customer support teams that need to compare Japan Standard Time with locations in the United Kingdom, Ireland, or Iceland on the same timeline.
Select the time range directly on the grid: Click Select, then drag across the JST row to highlight the hours you want to compare; the selected block turns purple and can be resized with the left and right handles or moved by dragging the center. For example, if you drag around 9:00 JST, the grid shows 0:00 GMT, while 12:00 JST = 3:00 GMT, 15:00 JST = 6:00 GMT, and 18:00 JST = 9:00 GMT, making it easy to see whether a Japan afternoon meeting lands in the early morning for GMT participants.
Export the selected meeting window: Once a range is selected, use the export options for ICS download, Google Calendar, Gmail, Copy to clipboard, or Share link. This is useful when a Tokyo team wants to send a confirmed meeting slot to colleagues in GMT countries so everyone receives the same event in their local calendar without manually rechecking the conversion.
Understanding the JST to GMT Time Difference
JST is Japan Standard Time, UTC+9, while GMT is Greenwich Mean Time, UTC+0. GMT is 9 hours behind JST, so a time in Japan converts to an earlier time on the same date or around midnight in GMT depending on the hour selected. The most practical reference points are 9:00 JST = 0:00 GMT, 12:00 JST = 3:00 GMT, 15:00 JST = 6:00 GMT, and 18:00 JST = 9:00 GMT.
JST does not observe DST, so Japan keeps the same UTC offset all year. GMT is a standard-time abbreviation, and its DST counterpart is IST, which means the JST-to-GMT difference changes during the part of the year when locations that normally use GMT switch to daylight saving time. In standard-time months, the relationship remains the fixed 9-hour gap shown above.
This matters for organizations working between Japan and GMT countries such as the United Kingdom, Ireland, Iceland, Ghana, Senegal, and Sierra Leone. A team using Japan business hours may find that even late-morning or afternoon JST slots still appear as midnight, early morning, or morning in GMT, so the exact season can affect whether a call is merely early or extremely early for the GMT side when DST is in effect under IST rather than GMT.
Best Times for Calls and Meetings Between JST and GMT
The examples show that JST daytime hours map to very early GMT hours. 9:00 JST = 0:00 GMT is midnight, 12:00 JST = 3:00 GMT is deep overnight, 15:00 JST = 6:00 GMT is early morning, and 18:00 JST = 9:00 GMT is the first example that clearly reaches a normal GMT workday start. For most business calls, this means early JST hours are poor for GMT participants, while later JST hours are more realistic.
If you need overlap between a Japan-based team and a GMT-based team, the most workable window from the examples is around the later part of the JST day. A meeting near 18:00 JST / 9:00 GMT can fit a standard morning start in GMT while still staying within the same business day in Japan. By contrast, 12:00 JST / 3:00 GMT and 15:00 JST / 6:00 GMT are usually too early for normal office schedules in the United Kingdom, Ireland, or West African GMT countries unless the meeting is for operations, logistics, or incident response.
This pattern is common in industries with Japan-to-Europe coordination, including manufacturing supply chains, gaming, electronics, shipping, and multinational customer support. A Tokyo team handing work to colleagues in London or Dublin often uses the late JST afternoon or early evening because it creates the clearest overlap with the beginning of the GMT workday. If your organization works across several GMT countries such as the United Kingdom, Ghana, Liberia, or Iceland, the same JST-to-GMT grid helps you identify whether a single slot is practical across all participants.
Frequently Asked Questions
What is the time difference between JST and GMT?
JST is 9 hours ahead of GMT, which means GMT is 9 hours behind JST. In practical terms, when it is 9:00 JST, it is 0:00 GMT, so Japan daytime often corresponds to overnight or early morning hours in GMT.
When is 9 AM JST in GMT?
9:00 JST = 0:00 GMT. This means a 9 AM start in Japan lands at midnight in GMT, which is usually unsuitable for regular business meetings unless the GMT side is handling overnight operations or urgent support coverage.
When is 12 PM JST in GMT?
12:00 JST = 3:00 GMT. A noon meeting in Japan therefore reaches GMT in the middle of the night, which is important for teams planning live calls, training sessions, or customer meetings involving Japan and GMT-based offices.
When is 3 PM JST in GMT?
15:00 JST = 6:00 GMT. That places a mid-afternoon Japan meeting into early morning GMT, which may work for some operations teams or early-shift staff but is still earlier than standard office hours for many participants.
When is 6 PM JST in GMT?
18:00 JST = 9:00 GMT. This is one of the most practical examples for real business use because it aligns Japan early evening with the start of a normal GMT workday, making it a strong option for recurring cross-border meetings.
Does the time difference between JST and GMT change during DST?
JST does not observe DST, so Japan stays on UTC+9 all year. GMT is a standard-time abbreviation, and its DST counterpart is IST, so the JST-to-GMT difference changes during the months when GMT-based regions move onto daylight saving time and are no longer on GMT standard time.
Which countries use JST and which countries use 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, which makes JST-to-GMT conversion relevant for trade, travel, media, and remote team coordination across Europe and West Africa.
What is the best meeting time between JST and GMT?
Based on the examples, later JST hours are the most practical because earlier Japan times convert to midnight or pre-dawn GMT. 18:00 JST = 9:00 GMT is the clearest business-friendly overlap shown here, making it a strong choice for sales calls, project handoffs, and weekly team meetings between Japan and GMT-based participants.