Direct answer
Asian forex session length is commonly described as about 10 hours. In practice, the “Asian session” is a convention, not a fixed clock time, so the exact start and end can shift depending on which market-hours definition (and time zone) you use.
Explanation: what “hours long” means for sessions
In forex liquidity-by-session discussions, a session “length” is usually measured as the time window when that region’s market activity is most visible in currency trading. For the Asian window, this is often treated as covering roughly two overlapping periods of trading (late Asia/overnight through to the overlap with later sessions), which is why many references land near 10 hours.
A key limitation is that forex trading continues nearly 24 hours on weekdays, so “session hours” represent relative activity and liquidity, not a hard on/off switch. Activity can start earlier than a label suggests and can continue after the label ends.
Example checks you can do independently
To make the “about 10 hours” figure concrete for your use case, compare two independent session definitions:
- Time-zone check: Pick a time zone (for example, your local time) and map the session window to it. If one definition shifts the start by an hour, the implied duration can appear different.
- Calendar vs. broker hours check: Use a session calendar and compare it with your broker’s trading hours. Even if the overall forex market runs continuously, brokers may present slightly different “platform session” labels.
- Overlap check: Look for the overlap period with other major trading activity (often late in the Asian window). Overlaps can make “duration” feel longer in practice than the headline number.
Limitations and what can’t be guaranteed
Because “Asian session” is a convention, not a single universal standard, any single number (like 10 hours) should be treated as an approximation tied to a chosen definition. Without specifying the exact session calendar convention and time zone, you cannot confirm a precise duration for every setting. Also, this explanation does not predict market outcomes; it only clarifies how long the session is commonly defined and why it varies.
Summary comparison
A common convention: ~10 hours for the Asian forex session. A practical reality: the observed active period may be longer or shorter depending on the time-zone mapping and the chosen start/end rules.