GMT vs JST Time Difference
See how Greenwich Mean Time compares with Japan Standard Time, including the 9-hour gap, DST effects, and the best times to schedule calls.
GMT to JST Difference
Japan Standard Time is UTC+9, which puts JST 9 hours ahead of Greenwich Mean Time year-round. Use this page to see the current offset and compare working hours side by side.
DST Impact and Changes
GMT stays at UTC+0, while Japan Standard Time does not observe daylight saving time. Offset calculations update automatically using the IANA timezone database to reflect seasonal and historical rule changes.
Best Meeting Time Windows
Find overlapping hours with a visual comparison grid, hour-by-hour tables, and practical meeting windows for the UK and Japan. Export selected times as ICS files or add them to Google Calendar and Gmail.
How to Find the Time Difference Between GMT and JST
Open the GMT vs JST converter: Visit https://www.xconvert.com/time-converter/gmt-vs-jst to see GMT (Greenwich Mean Time) and JST (Japan Standard Time) already loaded in the comparison grid. This view is useful when you are planning a call between the United Kingdom and Japan, coordinating a remote engineering handoff with a Tokyo team, or checking whether a London-based support shift overlaps with business hours in Japan.
Add comparison cities: Click + Add City and search for cities that matter to your schedule, such as London, Tokyo, or another GMT location used by your team. This is especially practical for finance, gaming, manufacturing, and logistics teams that work across the UK and Japan, where a single meeting may need to fit both European office hours and Japanese evening availability.
Select a workable time range: Click Select to enter selection mode, then drag across the colored timeline on the GMT row to highlight a meeting window in purple. For example, dragging 9:00 GMT to 12:00 GMT shows the corresponding 18:00 JST to 21:00 JST, which helps confirm that a late-afternoon discussion in Japan lines up with a morning slot in GMT; dragging 15:00 GMT to 18:00 GMT shows 0:00 JST to 3:00 JST next day, making it clear that this range is usually too late for Tokyo-based participants.
Export and share the result: After selecting the range, use the export options for ICS download, Google Calendar, Gmail, Copy to clipboard, or Share link. This is useful when a UK account manager needs to send a confirmed meeting slot to a client in Japan, or when a distributed team wants everyone to receive the same meeting time in their own local calendar automatically.
GMT vs JST Offset Explained
GMT is UTC+0 and JST is UTC+9, so JST is 9 hours ahead of GMT and GMT is 9 hours behind JST. In practical terms, 9:00 GMT = 18:00 JST and 12:00 GMT = 21:00 JST, which often makes GMT mornings the most realistic overlap for same-day business communication with Japan.
The gap becomes more restrictive later in the GMT day because 15:00 GMT = 0:00 JST (next day) and 18:00 GMT = 3:00 JST (next day). That means an afternoon meeting in a GMT-based office can easily push into midnight or early morning in Japan, which is why UK-Japan meetings are commonly scheduled earlier in the GMT workday.
Seasonal changes matter because GMT is a standard-time abbreviation, and its daylight-saving counterpart is BST. JST does not observe DST, so Japan stays on the same time standard year-round; when a location using GMT shifts to BST, the relationship changes from the standard GMT-to-JST pattern shown on this page, which is important for companies in the United Kingdom that coordinate with Japanese offices, suppliers, game studios, or trading partners across different parts of the year.
GMT is used across multiple countries, including 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, so this comparison is especially relevant for international trade, automotive supply chains, technology partnerships, shipping coordination, and customer support coverage between Japan and GMT-based regions.
Frequently Asked Questions
What is the time difference between GMT and JST?
JST is 9 hours ahead of GMT, and GMT is 9 hours behind JST. A simple way to see it is through common conversions such as 9:00 GMT = 18:00 JST and 12:00 GMT = 21:00 JST, which show that Japan is already well into the evening when it is still morning in GMT.
Is Japan always 9 hours ahead of GMT?
For the GMT-to-JST comparison shown here, yes: JST is 9 hours ahead of GMT. JST does not observe DST, so Japan keeps the same standard time throughout the year; the main seasonal complication comes from places that use GMT in winter and switch to BST in their daylight-saving period.
Does JST have daylight saving time?
No, Japan Standard Time does not observe DST. That makes Japanese scheduling more predictable for international teams, because Tokyo and other Japanese business centers stay on JST year-round without seasonal clock changes.
Why does the GMT and JST meeting overlap feel so limited?
The overlap is narrow because Japan is far ahead in the day. For example, 12:00 GMT = 21:00 JST, which is already late evening in Japan, and 15:00 GMT = 0:00 JST next day, which pushes the meeting into midnight for Japanese participants; this is why most GMT-JST calls are scheduled in the GMT morning.
What are good example meeting times between GMT and JST?
The most workable examples are usually earlier in the GMT day, such as 9:00 GMT = 18:00 JST or 12:00 GMT = 21:00 JST. These slots can work for cross-border client calls, supplier updates, or project reviews, while later examples like 18:00 GMT = 3:00 JST next day are generally unsuitable for normal business hours in Japan.
Which 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, so this comparison is especially useful for anyone scheduling communication between Japan and GMT-based teams, clients, or operations.
How do I convert GMT to JST quickly?
Use the fixed relationship on this page: JST is 9 hours ahead of GMT. The easiest reference points are 9:00 GMT = 18:00 JST, 12:00 GMT = 21:00 JST, 15:00 GMT = 0:00 JST next day, and 18:00 GMT = 3:00 JST next day, which cover common morning, midday, afternoon, and evening scenarios.
Is GMT or JST better for scheduling international business calls?
Neither is universally better; the best choice depends on whose working hours you need to protect. For UK-Japan coordination, anchoring the meeting in the GMT morning usually works better because it maps to JST evening, while meetings set in the GMT afternoon often land after midnight in Japan, as shown by 15:00 GMT = 0:00 JST next day.