<p>Heathrow allows up to two pieces of hand baggage through security, each no larger than 56cm x 45cm x 25cm, and liquids in containers up to 2 litres can stay inside your bag rather than being bagged separately. This is a genuinely different rule from most other UK and international airports, which still cap liquids at 100ml, so it matters which airport you are flying home from as well as which one you are leaving. Checked 2026.</p>
<h2>Heathrow's two-bag policy and maximum size</h2>
<p>Heathrow operates what it calls a two-bag policy at security. You can take up to two items of hand baggage through the checkpoint, and each one must be no larger than 56cm x 45cm x 25cm (22in x 18in x 10in). A handbag, laptop bag or small backpack each counts as one of your two items. Anything larger has to go in the hold as checked baggage, and bag gauges are available at check-in if you want to check the size before you reach security.</p>
<p>This is Heathrow's own security-checkpoint limit, separate from your airline's cabin baggage allowance. Airlines set their own size, weight and number-of-bags rules for what you can bring on board, and these can be stricter than Heathrow's 56x45x25cm maximum, particularly on budget carriers that charge extra for a larger cabin bag. Always check your airline's allowance before you travel, since passing Heathrow security with a bag does not guarantee your airline will let you board with it for free.</p>
<h2>The 2-litre liquids rule, and why it changed</h2>
<p>Since January 2026, Heathrow has completed the rollout of new CT security scanners across all four of its terminals (T2, T3, T4 and T5), and as a result it raised its liquids limit from the old 100ml-per-container rule to containers of up to 2 litres each. Liquids can stay inside your cabin bag for screening; you no longer need to remove them or pack them into a clear plastic bag. The same upgrade means laptops, tablets and other large electronics can also stay in your bag rather than being scanned separately. Heathrow was the largest airport in the world to complete this rollout, following the same upgrade at some other UK airports including Gatwick, Edinburgh and Birmingham.</p>
<div class="table-wrap"><table><thead><tr><th>Item</th><th>Heathrow rule (2026)</th></tr></thead><tbody><tr><td>Number of hand baggage items</td><td>Up to 2 per passenger</td></tr><tr><td>Maximum bag size</td><td>56cm x 45cm x 25cm (22in x 18in x 10in)</td></tr><tr><td>Liquids, gels and aerosols</td><td>Up to 2 litres per container, stays in your bag</td></tr><tr><td>Laptops and large electronics</td><td>Can stay in your bag, no separate tray needed</td></tr><tr><td>Reusable metal or insulated bottles</td><td>Must be emptied before security, refill after</td></tr></tbody></table></div>
<h2>Important: this only applies to flights leaving Heathrow</h2>
<p>The 2-litre rule is a Heathrow security-equipment change, not a change to UK or international law generally. If you are flying home to Heathrow from another airport, the old 100ml liquids limit and clear-bag requirement may well still apply there, since not every airport has finished installing the new scanners. Always check the security rules of the airport you are departing from before your return journey; do not assume the airport you land at governs what you can carry from the airport you are leaving.</p>
<h2>Baby food, breast milk and medicines</h2>
<p>Baby food, formula milk and breast milk can all be carried in your cabin bag in containers up to 2 litres each, and breast milk can be carried even if you are travelling without your baby, as long as it is in liquid form (not frozen) and in a clear container or a commercially available storage bag; metal or double-walled containers are not permitted for breast milk. Liquid medicines can also be carried in your cabin bag, and if you need to carry more than 2 litres of a liquid medicine for your journey, bring a prescription or a letter from your doctor confirming it is needed for the flight. Any medicine you will not need in flight is best packed in your hold baggage instead. If you are travelling with a baby more generally, see the guide to whether <a href='https://heathrowairportguide.pages.dev/articles/can-you-take-a-pushchair-through-heathrow-security'>you can take a pushchair through Heathrow security</a>.</p>
<h2>Food, powders and connecting flights</h2>
<p>Most food and powders are allowed in hand luggage, but they can slow down X-ray screening and trigger additional checks, so packing them in your hold bag where possible can speed up your trip through the checkpoint. If you are travelling onward to the United States, powders over 350g or 350ml are not allowed in cabin baggage (with some exemptions such as medicines and baby powder), and if you are flying to Australia the destination country's own 100ml liquids limit applies regardless of Heathrow's own rule, so check the requirements of your final destination as well as Heathrow's. If you are connecting through Heathrow rather than starting your journey here, the same 2-litre liquids and electronics rule applies at the connections security checkpoint too; see the guide on <a href='https://heathrowairportguide.pages.dev/articles/is-it-safe-to-self-connect-at-heathrow-airport'>self-connecting at Heathrow</a> and on <a href='https://heathrowairportguide.pages.dev/articles/do-i-need-to-collect-my-bags-on-a-heathrow-connection'>whether you need to collect your bags on a connection</a> for more on how transfers work here.</p>
<h2>What you cannot take through Heathrow security at all</h2>
<p>Some items are restricted or banned outright regardless of container size, including certain sharp objects, some sports equipment, and dangerous goods such as flammable liquids or aerosols in commercial quantities. Spare lithium batteries, power banks and e-cigarettes have their own separate rules covering how they must be carried, which are different from the liquids rules above; if you are packing any of these, it is worth reading a dedicated summary of the current UK regulations before you pack.</p>
<h2>Duty-free liquids bought after security</h2>
<p>Liquids, aerosols and gels bought airside after you have cleared security, including duty-free alcohol and perfume, can be carried onto your flight even in larger quantities, but they must be sealed at the point of sale in a security tamper-evident bag (STEB) with the receipt visible inside. If you are connecting through another airport afterwards, keep the STEB seal intact, since a second security check elsewhere may otherwise treat the liquid as a new, unscreened item.</p>
<h2>The takeaway</h2>
<p>At Heathrow in 2026, you can carry two bags of up to 56x45x25cm each through security, with liquids and electronics allowed to stay inside them in containers up to 2 litres. That is a real advantage over airports still running the older 100ml rule, but it is a Heathrow-specific and departure-specific rule, so always check the airport you are flying home from separately, and check your airline's own cabin baggage size and weight allowance, which can still be stricter than Heathrow's security limit.</p>