Airport security rules for liquids and electronics

Laptops and other large electronics, roughly anything bigger than a phone, come out of the bag and go in a separate tray at most checkpoints. That includes full-size tablets, games consoles and large cameras. Smaller devices, phones, e-readers and most compact tablets, can usually stay in the bag, but some airports still ask for all electronics out, so keep them in an accessible pocket.

Two practical points matter more than the rule itself. First, charge your devices. Security may ask you to power a laptop or phone on to prove it is a real device, and a dead battery can mean the item is refused. Second, cables and chargers tangle the X-ray image and slow the lane down; coil them or use a cable pouch so the officer can see through the bag.

Power banks and spare lithium batteries are normally cabin-only, never in checked baggage, but the rule is not one-size-fits-all: it depends on the battery type (lithium-ion, lithium-metal, non-removable) and on the airline and regulator rules that apply to your flight. Capacity limits are usually expressed in watt-hours (Wh), with many airlines allowing up to 100 Wh without asking, 100-160 Wh with airline approval, and refusing anything above 160 Wh. Check your airline's own page for the exact limits and packing instructions before you fly.

If you are travelling with a drone, a large camera rig or medical electronics, check the airline's rules as well as the airport's. Drones with lithium batteries follow the power-bank rules, and some countries restrict bringing them in at all.

CT scanners take a three-dimensional image, so officers can see inside a bag without it being unpacked. At airports that have them fully rolled out, you can usually leave liquids and laptops in your bag, and the liquid limit may be raised above 100 ml. The UK has been rolling these out at major airports, and several European and US hubs have them in some lanes.

The catch is that rollout is partial and the limits vary by airport and lane. An airport can have CT lanes in one terminal and old lanes in another, a lane can be switched back to the old rules on any given day for maintenance or staffing, and the permitted container size differs from one CT airport to the next. Airports that have not finished the upgrade still enforce 100 ml. This is why the safe move is unchanged: pack to 100 ml unless your departure airport's own page confirms a larger limit, and treat any relaxation as a bonus rather than a plan.

There is also a transfer trap. Even if your departure airport lets you keep a larger bottle of water, the airport where you change planes may not. If your connection requires you to clear security again, you will be back to 100 ml there. Long-haul itineraries with a change in a different country are the most likely place to lose a full-size bottle.

Security itself is free. The costs are the things you buy because of it. Airport shops sell clear bags and travel-size toiletries, usually at a large markup over supermarket prices at home. Decanting at home is the cheapest option by a wide margin.

The real cost is time, and it is variable. Checkpoint throughput depends on the airport, the time of day, staffing and how many bags are pulled for secondary screening, so no single queue rate applies. Airline advice is commonly to arrive two hours before a short-haul flight and three hours before a long-haul flight; add more at large hubs during holiday peaks and if you are checking bags. Treat those as planning figures, not guarantees.

If you are stopped, the usual outcome is a bag search. Officers remove the item, test it, and either let you keep it or confiscate it. Confiscated liquids are not returned and are not refunded. In rare cases, a concealed or misdeclared item can lead to a fine or denied boarding, but a forgotten water bottle normally just means it goes in the bin.

Medical liquids, baby milk and baby food are the main exemptions, but the procedure is country-specific and can differ between airports in the same country. In the US, TSA publishes its own rules for medically necessary liquids, breast milk, formula and baby food; the UK, EU, Canada, Australia and New Zealand each set their own carve-outs, and the requirement to declare, the documentation accepted and the possibility of testing all vary. Check the official security page for every airport on your itinerary and declare the item to an officer before screening.

Mobility aids, CPAP machines and other medical devices usually go through separately and are not counted as your one cabin bag by most airlines, but you should tell the airline in advance. Security may swab them. If you use a liquid that must stay cool, ask the airline about ice packs; frozen gel packs are sometimes treated as liquids.

There are also country-level differences worth knowing. Australia and New Zealand are strict about food, plant material and animal products at the border, which is a customs matter rather than a security one, but the same trip can involve both checks. The US and Canada both require laptops out at most lanes. Some countries ask for shoes off, belts off and jackets off; others do not. None of this is uniform, so read the airport page for each end of your trip.

The most frequent mistake is the oversized container: a 150 ml bottle with a little left in it. The second is a full water bottle bought before security and forgotten in the bag. The third is a power bank in checked luggage, which is a safety rule rather than a security one and is enforced by the airline under its own battery policy.

Other repeat offenders: liquids in a bag that is too big or not resealable, electronics buried at the bottom of a packed bag, a dead laptop that cannot be switched on, and duty-free alcohol bought at a transfer airport and then re-screened at the next one. Each of these adds time and, in the worst case, costs you the item.

The fix is a routine. Pack the liquids bag first and keep it in an outer pocket. Keep electronics in a single accessible pouch. Charge everything the night before. Empty your water bottle before you join the queue, not at the belt. Do those four things and the checkpoint becomes a short stop.

The day before, check three things: your departure airport's security page, your airline's lithium battery rules, and whether your itinerary involves a transfer where you clear security again. Those three checks cover almost every surprise at the checkpoint.

The night before, pack the liquids bag, charge every device, and move power banks into your cabin bag. If you are travelling with medical liquids or baby supplies, put the documentation with the items, not in the checked suitcase.

On the day, arrive early, empty your water bottle before the queue, and put the liquids bag and electronics where you can reach them without unpacking. If an officer asks you to step aside, stay calm, answer the questions and let them test the item. It is a routine stop, not an accusation.