Whether you can walk between terminals at London Heathrow (LHR) depends entirely on which terminals you are moving between. Terminals 2 and 3 are connected by a well-signed pedestrian underpass, making the walk between them relatively easy and taking about 10–15 minutes. However, Terminals 4 and 5 are geographically separate and cannot be reached on foot. To travel between T2/T3 and Terminal 4 or 5, you must use the free inter-terminal transport, which includes the Heathrow Express train, the Elizabeth Line, or the underground Tube (all of which are free for travel between terminals). There are also dedicated shuttle buses for transit passengers who have already cleared security and are moving "airside." For 2026 travelers, it is important to note that Heathrow is massive; even within a single terminal (especially Terminal 5), you might need to take an automated "people mover" train to reach the satellite gates, so always allow at least 20 minutes for any inter-terminal or long-gate transfer.