Heathrow has four terminals — T2, T3, T4 and T5 — and moving between them is free, whether you're a connecting passenger or simply need to reach a different terminal landside. The two dedicated options are the inter-terminal buses, which run around the clock, and the Heathrow Express segment between T2/3 and T5, which is free for connecting passengers only. Allow 60 to 90 minutes for any transfer, and specifically 90 minutes between T4 and T5, as this is the longest and most indirect route.
The free ways to move between terminals
Inter-terminal buses (airside, 24/7)
The main way to get between terminals for free is the dedicated inter-terminal bus network, which operates 24 hours a day, seven days a week. These buses are aimed at connecting passengers and run on the airside road network, linking T2/3 with T4 and T5. Look for purple "Flight Connections" signage from the arrivals area of your terminal — staff and signage will direct you to the right stop.
Because these buses use airside roads, they're generally the quickest option if you're already through security and simply switching terminals for a connecting flight, rather than leaving the airport and coming back in.
Heathrow Express (free segment, connecting passengers only)
Heathrow Express trains run between the central terminals (T2/3) and T5, and the same train that fare-paying passengers use to reach central London is free for anyone making a connection between those two terminal areas. This is worth knowing if you'd rather take the train than a bus — it's fast and frequent — but it's only free for transfers; if you're travelling landside to or from central London, the standard fare applies (see our guide to public transport fares at Heathrow for current prices, checked 2026).
Piccadilly line and Elizabeth line (paid, back-up option)
The London Underground's Piccadilly line has a station between T2 and T3, another at T4, and another at T5, so it can technically be used to move between terminals too. The Elizabeth line also calls at all three Heathrow stations (T2/3, T4 and T5). Neither of these is the dedicated free transfer, though — you'll pay a standard Tube or Elizabeth line fare each time you tap in, and you'll typically need to go landside through ticket barriers to use them. Treat this as a fallback if the inter-terminal bus or train isn't convenient, not as your first choice for a free connection.
How long to allow
As a general rule, budget 60 to 90 minutes to move between any two Heathrow terminals, door to door, including walking to the transfer point and waiting for the bus or train. Some transfers are quicker — T2 and T3 are close together and well connected — but others take longer:
- T2/T3 to T4 or T5: typically towards the lower end of the range.
- T4 to T5: allow the full 90 minutes. This is the longest inter-terminal journey at Heathrow, and the one where cutting it fine is most likely to cause problems.
If your connection time is shorter than this, it's worth checking directly with your airline before you fly. Our related guide on connection times at Heathrow breaks down minimum connection times in more detail.
Do you need to clear security again?
This is the detail that catches people out, and it genuinely varies by routing. Connecting passengers travelling on a single ticket, with bags checked through to their final destination, can often stay airside for the whole transfer, using the dedicated Flight Connections bus or train without leaving the secure zone. But this isn't guaranteed for every itinerary — it depends on your airline, whether your ticket is a single booking or two separate tickets, and which terminals are involved.
Given that Heathrow's security queues typically run 15 to 30 minutes at busy times, it's worth building that in as a possibility even if you expect to stay airside. The safest approach: confirm with your airline, or at the assistance or transfer desk at your arrival terminal, whether your specific connection requires you to clear security again.
If you're self-connecting on separate tickets, or need to collect and recheck baggage, assume you'll go landside and pass back through security and check-in, which takes longer than an airside transfer — factor this into your planning alongside the transfer time above.
If you're not connecting — just visiting another terminal
Not every terminal move is a flight connection. You might be dropping someone off at a different terminal, meeting a friend, or need to reach a specific check-in desk. Here, the same free inter-terminal buses work landside too, and the Piccadilly or Elizabeth line are straightforward if you're happy to pay a standard fare. If you're arriving by car or taxi, it's sometimes simpler and not much pricier to be dropped directly at the correct terminal rather than transferring once inside — worth weighing up with heavy luggage or a tight schedule. First, make sure you know which terminal you actually need: see our guide on finding your Heathrow terminal.
If your layover is long enough that you're considering leaving the airport altogether rather than just switching terminals, read our separate guide on leaving Heathrow during a layover before you go landside, as re-entering involves security again and its own time cost.
For more general questions on getting around Heathrow, our FAQs page covers fares, drop-off charges and other common queries, all checked 2026.
FAQs
Are Heathrow's inter-terminal buses really free?
Yes. The dedicated inter-terminal bus service runs 24/7 between T2/3, T4 and T5 at no charge, checked 2026. Follow the purple Flight Connections signs from your arrivals area.
Is the Heathrow Express free between terminals?
Only for connecting passengers moving between T2/3 and T5. It's the same train used by paying passengers heading to central London, but transfers between those two terminal areas don't incur a fare, checked 2026.
How long should I allow to change terminals at Heathrow?
Generally 60 to 90 minutes. Allow the full 90 minutes for a T4 to T5 transfer specifically, as it's the longest route, checked 2026.
Will I have to go through security again when I change terminals?
It depends on your ticket and routing. Many single-ticket, bags-through connections stay airside without re-clearing security, but this isn't guaranteed for every itinerary. Confirm with your airline or at the transfer desk for your specific connection.
Can I use the Tube to get between terminals?
Yes, technically — the Piccadilly line stops between T2 and T3, and at T4 and T5, and the Elizabeth line also serves all three Heathrow stations. However, this means paying a standard fare and usually going landside, so it's a back-up rather than the dedicated free transfer.
Do I need to collect my bags to change terminals?
Usually not, if you're connecting on a single ticket — your airline checks bags through to your final destination. If you're self-connecting on separate tickets, you'll normally need to collect and recheck your bags, which adds time beyond the standard transfer window.