Direct answer: London–New York overlap time
The “London–New York overlap” in forex usually means the period when the London trading session and the New York trading session are both in progress at the same time, so liquidity and market activity can be higher than during a single session.
There is no single fixed clock time that is correct every day all year, because the UK and the US can enter daylight saving time on different dates. To get the overlap time for a specific day, you must convert both sessions into the same time zone (commonly UTC or your local time zone) and then find the hours that overlap.
Mechanics: how the overlap is determined
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Define session times in their local references. London hours are based on UK local time, and New York hours are based on US local time.
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Convert both to one common time zone. For verification, UTC is often easiest because it avoids local time confusion.
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The overlap is the intersection. If London runs from A to B in the chosen time zone, and New York runs from C to D, the overlap hours are from max(A, C) to min(B, D).
If you are checking a schedule that already lists sessions in UTC, you can directly compare the two ranges without doing extra conversions.
If a schedule lists sessions in “UK time” and “US time,” you still can compute overlap, but you must track whether each region is currently on standard time or daylight saving time.
Example checks you can do independently
- Pick a specific date and look up the UK and US daylight saving status for that date.
- Convert the published London session range and the published New York session range to UTC.
- Mark the overlapping portion on a simple timeline.
This approach keeps the result verifiable and repeatable. If you use a different time zone than UTC, you should still convert both sessions first; otherwise, you may accidentally shift the overlap by one hour.
Limitations and uncertainty
- Overlap timing is definition-dependent: some sources describe session hours slightly differently (start/end times and whether they include pre-market or wrap-up periods).
- Daylight saving time changes mean overlap can shift by an hour between periods of the year.
- This explanation does not provide real-time “right now” overlap timing, because that would require a current date/time and current daylight saving rules.
Comparable view: overlap vs. single-session hours
Compared with a time when only one session is active, the overlap window is where participants from both regions can be active simultaneously. However, overlap does not imply identical conditions every day; spreads, liquidity, and activity can still vary by instrument and calendar events.