What you can actually carry in hand luggage

Two different questions get asked as one. How much hand luggage you are allowed — a size, a weight, a number of bags — is set by the fare you bought, and the baggage page covers that half.

This is the other half: what may be inside it. That is decided by aviation security where you depart, by customs where you land, and occasionally by the aircraft itself. None of the three is negotiable at the gate.

Liquids, and why the rule is changing unevenly

The familiar rule is containers of 100 ml or less, together in one transparent resealable bag of about a litre. What counts as a liquid is broader than it sounds: gels, pastes, creams, aerosols and anything soft enough to be squeezed all sit under it, which is why toothpaste and mascara belong in the bag.

Newer CT scanners can see through a full bottle, and airports that have installed them have started relaxing the limit. This is where it gets confusing: the relaxation is per airport, sometimes per terminal, and it has been reversed more than once. An airport that let you through with a full water bottle in spring may not in autumn.

Pack for the strictest airport on your itinerary, not the one you are standing in. A connection means a second security check, under whichever country's rules apply there.

Medication and baby food are exempt from the volume limit in most jurisdictions, but expect to declare them and have them screened separately. A prescription or a pharmacy label makes that conversation shorter.

The batteries rule, which runs the opposite way

Almost everything about packing says "put it in the hold". Lithium batteries say the reverse, and this is the rule most people get wrong.

Power bank

Cabin only, never checked. A fire in the hold is unreachable; in the cabin it is a crew with an extinguisher.

Spare batteries

Cabin only, terminals taped or in their own pouches so nothing can short against a coin.

Devices with batteries inside

Either, but cabin is better — a phone or a laptop in checked luggage is also a theft problem.

Capacity limits apply above roughly 100 Wh, where a carrier's permission is usually needed, and above 160 Wh, where the answer is generally no¹. Many airlines have also stopped allowing power banks to be used in flight, or to charge from the seat's USB socket.

Sharp, pointed, and the things that surprise people

Blades under a short length are allowed at some checkpoints and not others, so a pocket knife is the classic thing confiscated by a traveller who has flown with it before. Scissors are judged on blade length, tweezers and nail clippers are usually fine, and a razor is fine as a cartridge and not as a loose blade.

Less obviously: tools over a certain length, sporting equipment of almost any kind, and anything that reads as a replica — a toy gun, a prop — are cabin refusals even when they are plainly harmless.

Food, and the border that cares

Security rarely objects to food. Customs at the other end often does.

Meat, dairy, fresh fruit, vegetables, seeds and plants are the categories that get taken, and the rules belong to the destination rather than to the airline. Several countries treat an undeclared apple as a fine rather than a confiscation, which is why the declaration card asks.

Duty-free liquids bought after security travel in a sealed tamper-evident bag with the receipt inside. That seal is what makes them exempt — opening it before the last leg turns a bottle of gin back into a litre of liquid at the next checkpoint.

What the aircraft decides, late

A bag that satisfied the size frame can still be taken at the gate, because cabin space is finite and a full flight runs out of it. On the busiest routes this is routine rather than exceptional.

The practical consequence is a small one and worth the habit: keep documents, medication, valuables and anything with a battery in something you keep with you, so a bag taken at the gate costs you the bag and not the trip.