Yes, in most cases you can, as long as you are allowed to enter the UK. You clear passport control like any arriving passenger, which means you may need a UK ETA or a visa, then re-check in and re-clear security for your next flight. Realistically you want a layover of at least 6 hours to make it worthwhile. Checked August 2026.
The basic rule
Heathrow does not keep transit passengers sealed away from the country. If you want to leave the airport between flights, you go through UK immigration exactly as an arriving visitor would. There is no separate "transit only" shortcut that lets you into London without being admitted to the UK. So the real question is not whether the airport allows it, but whether you are eligible to enter the UK at all.
Can you actually enter the UK?
This is the part to check before you plan anything:
- Most visitors from countries such as the US, Canada, Australia and the EU can enter for a short visit, but from 2026 many now need a UK Electronic Travel Authorisation (ETA) before they travel. It costs £20 and is applied for through the official UK ETA app, valid for two years. Apply in advance, not at the airport.
- Some nationalities need a full UK visa to enter, even briefly.
- If you are staying strictly airside and connecting without passing through immigration, you may not need the same clearance, but the moment you want to leave the airport you are entering the UK and the entry rules apply.
Check your own status carefully. Our Heathrow entry requirements guide covers the ETA and eGates in more detail. If in doubt, confirm against gov.uk before you fly.
How much time do you need?
Leaving and coming back eats hours, so a short layover is not enough. Here is where the time goes on the way out and back in:
| Step | Rough time |
|---|---|
| Clear UK immigration on arrival | 15 to 45 min, longer at a peak |
| Collect bags if not checked through | Add time at the belt |
| Travel into London and back | 45 to 60 min each way by train |
| Re-check in for the next flight | Opens a few hours before, closes 60 min before long-haul |
| Re-clear security | Usually under 5 min, more at morning peak |
| Walk to the gate | Allow a buffer |
Add all that up and a 3-hour layover disappears before you have seen anything. A 6-hour layover gives you maybe a couple of hours in central London if everything runs smoothly. With 8 hours or more you can relax a little. The Elizabeth line gets you to Paddington in about 35 minutes for £15.50, or the Piccadilly line for around £5.60.
What you must do to fly out again
Leaving on a layover means you become a normal departing passenger for your onward flight. That means:
- Re-check in. If your onward flight is on a separate ticket, or your bags were not checked through, you must check in again and drop your bags. Check the bag-drop cut-off, often 60 minutes before departure for long-haul.
- Re-clear security. Every departing passenger at Heathrow goes through security screening again. Since January 2026 all terminals use CT scanners, so liquids up to 2 litres can stay in your bag.
- Mind the terminal. Your onward flight may leave from a different terminal than you arrived at. Allow 60 to 90 minutes to transfer between terminals using the free inter-terminal bus or train.
When it is not worth it
- Separate tickets with a tight gap. If you booked two unlinked flights, missing the second because you went sightseeing is entirely your risk and neither airline will help. See our connection time guide.
- You need a visa you do not have. No entry, no leaving the airport.
- Overnight arrivals. If the trains have stopped and the airport is in its quiet window, staying put is usually easier. Our overnight at Heathrow guide covers where to wait.
More
More: Overview, Public transport, FAQs.
Frequently asked questions
Can I leave Heathrow between connecting flights? Yes, if you are allowed to enter the UK. You clear passport control, which may require a UK ETA or visa, then re-check in and re-clear security for your onward flight.
Do I need a UK ETA to leave the airport on a layover? If your nationality requires one to enter the UK, then yes. The ETA costs £20, is applied for in advance through the official UK ETA app and is valid for two years. Check your status on gov.uk.
How long a layover do I need to go into London? Realistically at least 6 hours, because clearing immigration, travelling in and back, re-checking in and re-clearing security all take time. With 8 hours or more it is more comfortable.
Will I have to go through security again when I come back? Yes. Every departing passenger at Heathrow re-clears security. Liquids up to 2 litres can stay in your bag thanks to the CT scanners rolled out in January 2026.
What if my onward flight leaves from a different terminal? Allow 60 to 90 minutes to transfer, using the free inter-terminal bus or Heathrow Express segment, on top of check-in and security time.
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Last verified August 2026 by the Heathrow Airport Guide editorial team. Prices and timetables change, so confirm the specifics on the official Heathrow Airport website before you travel.