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Broker time & DST ​

Everything in the MT5 tester happens in broker server time, and that clock is neither yours nor London's. Getting session times right needs three things:

  1. Your broker's offset. Many MT5 brokers (most prop firms among them) run UTC+2 in winter and UTC+3 in summer, switching on the US daylight-saving dates, so their day starts at 17:00 New York. Others switch on EU dates or not at all.
  2. The session's own DST. London follows UK/EU dates, New York follows US dates.
  3. The weeks they disagree. The US switches about 3 weeks before the UK in March and 1 week after in October/November. In those weeks "London 08:00" is a different broker hour than the rest of the year.

How strategies handle it ​

The AI never hardcodes session hours in broker time. Strategies use the app's time-zone module, which converts a session time in its own city to broker time for any date:

cpp
#include <Studio/TimeZones.mqh>
input int  InpWinterOffset = 2;     // broker hours ahead of UTC in winter
input bool InpFollowsUSDST = true;  // broker switches on US dates (false = EU)

// broker time at which today's London 08:00 session opens
datetime open = SessionStartInBrokerTime(TimeCurrent(), TZ_LONDON, 8, 0,
                                         InpWinterOffset, InpFollowsUSDST);

Zones: London, New York, Tokyo, Sydney, UTC. Also BrokerToUTC() and UTCToBroker().

Set it for your broker ​

The two inputs live under Advanced on each strategy:

  • InpWinterOffset: your broker's UTC offset in winter (look at MT5's Market Watch clock against UTC in January).
  • InpFollowsUSDST: on if your broker changes its clock on the US dates, off for EU dates.

Verified, not assumed ​

The module's session times for London, New York, Tokyo and Sydney were checked hour by hour for 2021 to 2027 against the IANA time-zone database (the one operating systems use), with a broker clock of UTC+2/+3 on US dates. The check ships in the workspace: the TimeZonesCheck script (in tools/mql5/) writes the module's output from MT5, and tools/check_timezones.py compares it with the database (needs Python 3.9+).

TimeGMT() and TimeLocal() read your computer's clock, not the tested date, so strategies never use them.