Direct answer: London session open time
The “London session” in forex is commonly treated as starting when London’s main trading activity begins, which is typically around the London market opening in the morning local time. In practical terms, many traders interpret the London session as opening at about 08:00 London time (often described as 08:00 GMT or 08:00 BST, depending on daylight saving).
Because forex is traded around the clock across different venues, there is no single universal “open” moment for all forex liquidity. Different platforms and calendars may show slightly different session start times depending on their chosen definition (for example, the start of London trading hours, the start of a liquidity window, or a precomputed session schedule).
How “London session open” works (definitions you can verify)
To interpret “what time does London session open forex?” you need a consistent definition of “open”:
- London local market open: This refers to the start of London business hours that many market participants map to the London trading session.
- Session schedule on a forex calendar: Many tools publish session times in a specific time zone (often GMT or the user’s local time). If daylight saving shifts, the displayed start can move by an hour.
- Platform labeling: Some charts label “London session” using an internal rule tied to their data source, which can cause small discrepancies.
A quick way to verify independently is to check whether your calendar shows London’s start time as 08:00 in London local time, then confirm how it converts that to your time zone.
Checks and examples (time zone and daylight saving)
If your tool states London session open as 08:00 GMT, then during periods when London is on daylight saving time (BST), the same London-local start may appear as 09:00 in GMT-based calendars. Conversely, when daylight saving is not in effect, the GMT and London-local offsets align.
Another common mismatch happens when a platform uses “session open” as the start of a predefined intraday window (not exactly the same as the local market opening). In that case, the chart label might still say “London session,” while the actual first minute can differ by minutes or an hour.
Limitations and uncertainty
Forex sessions are interpretive labels rather than strict legal “opening times” for a single exchange. As a result, your exact displayed start time depends on:
- the time zone your tool uses;
- whether daylight saving is applied for London during that date;
- how the platform defines “session open.”
Use the same tool and the same definition when comparing session behavior, and treat any specific minute-level start time as approximate unless your calendar clearly states the rule behind it.