Changing terminals at Heathrow airport is fast and convenient, thanks to the airport’s comprehensive infrastructure. Terminals 1, 2 and 3 are in relatively close proximity to one another at the centre of the airport grounds, and it is actually possible to walk between them. Reaching Terminals 4 and 5 requires a quick transfer by bus or rail.
An underground walkway connects the central terminals, and it generally takes ten minutes to cross from one to the other. The Heathrow Express train also connects these terminals, though the transfer process (including average wait time) takes twice as long as walking.
Terminal 4 is connected to the others by the Heathrow Express, and – while the actual transfer time itself is quick – you can count on the entire process taking around 20 minutes. Terminal 5 is also served by the Heathrow Express, with support from an extension of the London Underground that connects to terminals 1, 2 and 3.
The Heathrow Express doesn’t work for transfer between terminals 4 and 5, as it would require stopping off at intermittent terminals along the way. Buses 490 and 482 are on hand for this particular transfer.