Terminals 2, 3, 4 and 5 are separate areas. Your transfer method depends on whether you are a connecting passenger inside the airport process or a landside traveler moving between terminals.
Protected flight connection
Heathrow tells connecting passengers to follow the purple Flight Connections signs. If a terminal change is required, the official connection flow can include a free transfer bus.
Landside terminal movement
Heathrow and TfL provide free inter-terminal rail transfer options under specific conditions. Use the official terminal-transfer planner for the exact pair rather than assuming one route fits all.
Self-transfer is different
Separate tickets may require immigration, baggage collection, check-in and security. That adds failure points and makes minimum airline connection times less relevant to your situation.
Check live status late in the process
Gate and operational information can change. Use the official Heathrow flight board and airline notifications close to departure.
Frequently asked questions
Can I transfer between Heathrow terminals for free?
Yes, Heathrow provides free transfer methods, but the route depends on the terminals and whether you are airside or landside.
Do connecting passengers pass security again?
Heathrow states that connecting passengers pass security before continuing.
Can I walk from Terminal 2 to Terminal 3?
Those two terminal areas are close enough for a pedestrian route landside; use Heathrow signage and the official planner.
Sources and verification
Time-sensitive airport, airline, visa, security and transport details should always be confirmed with the relevant official source before travel.