<p>If both your flights are on a single ticket, your checked bags are almost always transferred straight through by the airline and you won't need to collect them, but you will still go through security again at Heathrow. If you've booked two separate tickets, you're not technically a connecting passenger: you'll need to collect your bags, clear UK immigration, then check in and go through security again from scratch. Checked 2026.</p>
<h2 id="one-ticket-vs-two-tickets">The key distinction: one ticket or two</h2>
<p>Heathrow's own guidance draws a firm line here. A connecting flight, in the airport's terms, is when you book one ticket covering both flights, arriving on one and leaving on another from the same airport. If that's your booking, most passengers won't need to collect baggage since it's transferred directly by the airline, though it's worth checking with your airline if you're not sure, particularly on itineraries that mix airlines or alliances. If instead you've booked two separate tickets, sometimes called self-connecting, Heathrow treats you as two independent journeys rather than one connection, and the through-baggage arrangement doesn't apply.</p>
<h2 id="do-i-go-through-security-again">Do I go through security again either way?</h2>
<p>Yes. All connecting passengers at Heathrow must go through security checks again, regardless of whether their bags are transferred through or not, because any passenger flying out of a UK airport has to comply with UK security screening. This applies even if your connection is short and even if you never leave the airside area. Large electrical items and liquids up to 2 litres can stay in your cabin baggage when connecting, which is more generous than the standard 100ml liquid allowance for a first departure, but you should still follow the on-the-day instructions from staff in the security area since rules can vary by lane.</p>
<h3 id="what-if-i-change-terminals">What if I'm changing terminals?</h3>
<p>A terminal change adds a step but not a different process: you'll follow the purple "Flight Connections" signs to an airside bus or the Heathrow Express shuttle, then clear the same security screening at your new terminal before reaching the gate. For how much time to allow when a terminal change is involved, see our guide to <a href="/articles/heathrow-connection-times-how-long-between-flights">Heathrow connection times</a>, and check <a href="/articles/how-to-find-which-terminal-your-heathrow-flight-uses">which terminal your onward flight uses</a> as soon as you know the flight number.</p>
<h2 id="when-you-do-need-to-collect-bags">When you do need to collect your bags</h2>
<p>You'll need to collect checked luggage in three common situations: your flights are on separate tickets rather than one through-booking; your airline confirms it doesn't through-check bags on your specific routing (this can happen with some codeshare or interline combinations); or you're switching from an international flight onto a UK domestic flight, since bags sometimes need to be reclaimed and rechecked at that point depending on the airlines involved. If you're unsure, check with the airline that issued your ticket before you travel rather than assuming, since getting this wrong on the day can eat a large chunk of a tight connection.</p>
<div class="table-wrap"><table>
<thead><tr><th>Booking type</th><th>Collect bags?</th><th>Immigration?</th><th>Security again?</th></tr></thead>
<tbody>
<tr><td>Single ticket, international to international</td><td>Usually no</td><td>Usually no</td><td>Yes</td></tr>
<tr><td>Single ticket, international to UK domestic</td><td>Usually no</td><td>Yes</td><td>Yes</td></tr>
<tr><td>Two separate tickets</td><td>Yes</td><td>Yes</td><td>Yes, plus fresh check-in</td></tr>
</tbody>
</table></div>
<h2 id="immigration-on-a-connection">Do I need to go through immigration?</h2>
<p>Unless you're connecting onto a UK domestic flight, or you've booked two separate tickets, you generally won't pass through UK border control on an international-to-international connection at Heathrow. Where immigration is required, whether you also need a UK Electronic Travel Authorisation before you travel depends on your nationality and the type of transit, and it's worth checking gov.uk before you fly since the transit exemption rules have changed before.</p>
<h2 id="separate-tickets-in-practice">What separate tickets actually involve, step by step</h2>
<p>If you've self-connected on two tickets, plan for the full arrival process: clear UK immigration using either a staffed desk or the eGates if you're eligible, collect your checked bags from the reclaim belt, exit through customs, then re-enter the terminal landside to check in for your second flight, drop your bags again, and clear security once more. Each of those steps takes meaningfully longer at busy times of day than the single-ticket connecting process, which is why separate-ticket itineraries need a much larger time buffer, and why the airline carries no responsibility for rebooking you if the first flight is delayed. If you'll be landside for a while between flights, our <a href="/faqs/">Heathrow FAQs page</a> covers practical questions on parking, drop-off and getting into London while you wait.</p>
<h2 id="faqs">FAQs</h2>
<p><strong>Will my luggage automatically transfer to my connecting flight at Heathrow?</strong></p>
<p>Usually yes, if both flights are on one ticket. Most airlines through-check bags to your final destination, but confirm with your airline if your itinerary mixes carriers or alliances.</p>
<p><strong>Do I have to go through security again even on a short connection?</strong></p>
<p>Yes. Every connecting passenger at Heathrow goes through security again, regardless of how short the layover is or whether bags are being transferred.</p>
<p><strong>What if I booked two separate one-way tickets?</strong></p>
<p>You'll need to collect your bags, clear UK immigration, then check in and go through security again for your second flight, exactly as if starting a new journey.</p>
<p><strong>Can I keep liquids and electronics in my bag when connecting?</strong></p>
<p>Large electronics and liquids up to 2 litres can generally stay in your cabin bag when connecting at Heathrow, which is more generous than the usual first-departure allowance, but follow staff instructions on the day.</p>
<p><strong>Do I need to clear immigration if I'm only connecting between two international flights?</strong></p>
<p>Generally no, as long as both flights are on one ticket. Connecting from an international flight onto a UK domestic flight does require clearing immigration first.</p>
<p><strong>How do I know if my airline through-checks bags on my route?</strong></p>
<p>Check your booking confirmation or ask the airline directly, especially if your itinerary involves more than one airline or a mix of alliances, since through-check agreements vary by carrier partnership.</p>