Compare GMT vs JST
See the current time difference between GMT and JST, check DST effects, and find the best meeting hours across both time zones.
GMT to JST Difference
JST is 9 hours ahead of GMT year-round. Use this page to see the live offset and compare current local time in both zones.
DST Changes and Impact
JST does not observe daylight saving time, while GMT remains UTC+0 as standard time. The page tracks seasonal rule changes automatically using the IANA timezone database.
Best Meeting Time Finder
Use the visual hour-by-hour grid to spot overlapping work hours, then export meetings with ICS download or send to Google Calendar and Gmail.
How to Find the Time Difference Between GMT and JST
Open the GMT vs JST page: Go to https://www.xconvert.com/time-converter/gmt-vs-jst to load a visual comparison grid with GMT and JST already shown in separate rows. This is useful when you are planning a call between London-based partners working on GMT and colleagues in Japan, or when you need to confirm whether a late UK work session reaches Tokyo during business hours.
Add comparison cities if your schedule involves more than two regions: Click + Add City and search for places that commonly connect with GMT and Japan, such as London, Tokyo, or Dublin for finance, media, shipping, and multinational project work. This helps if your team includes UK operations on GMT and Japan-based suppliers, game studios, electronics manufacturers, or regional offices that need a shared meeting window.
Select a meeting window directly on the grid: Click Select to enter selection mode, then drag across the GMT row to highlight a time range in purple; you can move the range by dragging the center or fine-tune it with the left and right handles. For example, selecting 9:00 GMT to 12:00 GMT shows 18:00 JST to 21:00 JST, which is useful for checking whether a UK morning call lands in Japan’s early evening; selecting 15:00 GMT shows 0:00 JST (next day), which quickly reveals when a same-day UK meeting becomes a next-day midnight slot in Japan.
Export the selected time for your team: Once a range is highlighted, use the export options for ICS download, Google Calendar, Gmail, Copy to clipboard, or Share link. This is especially practical for cross-border coordination, such as sending an ICS invite to a Tokyo client, copying the converted time into Slack for a distributed team, or generating a share link so everyone sees the same GMT-to-JST overlap on the same date.
GMT vs JST Offset Explained
GMT is Greenwich Mean Time, UTC+0, while JST is Japan Standard Time, UTC+9. That means JST is 9 hours ahead of GMT, so when it is 9:00 GMT, it is 18:00 JST, and when it is 12:00 GMT, it is 21:00 JST. This gap is large enough that a standard workday in GMT often overlaps only with late afternoon and evening hours in Japan.
The time difference becomes even more important later in the GMT day. 15:00 GMT = 0:00 JST (next day) and 18:00 GMT = 3:00 JST (next day), so afternoon or evening activity in GMT can already fall into the next calendar day in Japan. For remote teams, this affects release planning, overnight support handoffs, and decisions about whether a meeting should happen on the same business date for both sides.
Seasonally, JST is straightforward because Japan Standard Time does not observe DST. GMT is a standard-time abbreviation, and its DST counterpart is IST, so the GMT label applies specifically to the standard-time period rather than year-round clock behavior in places that switch seasonally. In practical scheduling terms, if you are comparing a GMT-based schedule with Japan, it is important to confirm whether you are working specifically in GMT or in a daylight-saving period using a different abbreviation.
GMT is used across a wide set of countries and territories, including the United Kingdom, Ireland, Iceland, Ghana, Senegal, Sierra Leone, Liberia, Mali, Guinea, Guinea-Bissau, Burkina Faso, Gambia, Togo, Mauritania, Sao Tome and Principe, Saint Helena, Guernsey, Jersey, Isle of Man, and Ivory Coast. JST is used in Japan. That makes this comparison especially relevant for trade, shipping, manufacturing, gaming, automotive supply chains, and financial coordination between Japan and organizations operating on GMT time.
Frequently Asked Questions
What is the exact time difference between GMT and JST?
JST is 9 hours ahead of GMT. A simple way to see it is through common conversions: 9:00 GMT = 18:00 JST and 12:00 GMT = 21:00 JST. This means a morning schedule in GMT usually appears as an evening schedule in Japan.
Is Japan always 9 hours ahead of GMT?
Yes, Japan Standard Time remains 9 hours ahead of GMT in this comparison because JST does not observe DST. That consistency is one reason Japan is easier to schedule with than regions that change clocks seasonally, although you still need to watch for the next-day date shift when GMT meetings happen later in the day.
Does JST have daylight saving time?
No, JST does not observe DST. This means Japan keeps the same standard time throughout the year, which is helpful for recurring calls, customer support coverage, and long-term project planning with teams in Tokyo, Osaka, or other Japanese business centers.
Does GMT change for daylight saving time?
GMT is a standard-time abbreviation, and its DST counterpart is IST. In real scheduling, that means you should pay attention to whether a location is currently operating on GMT itself or on its daylight-saving counterpart, because the label used on the calendar or time tool affects the comparison with Japan.
If it is 3 PM GMT, what time is it in Japan?
15:00 GMT = 0:00 JST (next day). This is a critical conversion for anyone arranging late UK or West Africa calls with Japan, because what feels like an afternoon meeting in GMT becomes midnight in Japan and often falls outside normal business hours.
If it is 6 PM GMT, what time is it in JST?
18:00 GMT = 3:00 JST (next day). That makes early evening in GMT a very poor choice for most business meetings with Japan unless you are coordinating maintenance windows, overnight operations, or urgent incident response that requires off-hours availability.
What countries use GMT and which country uses JST?
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. JST is used in Japan. This comparison is common in international trade, logistics, media distribution, and supplier communication where organizations in the UK or West Africa need to coordinate with Japanese partners.
Is a GMT morning a good time to meet with Japan?
A GMT morning is often one of the more workable options because 9:00 GMT = 18:00 JST and 12:00 GMT = 21:00 JST. That creates a window where GMT-based teams can meet before lunch while Japan joins in the evening, which is often more practical than scheduling in the GMT afternoon, when Japan has already moved into the next day.