What you can't bring on a plane: liquids, power banks, batteries and sharp items

Most things are fine to fly with. The items that cause trouble at security, or that an airline will not let you check in, fall into a few groups: liquids, power banks and other lithium batteries, e-cigarettes, sharp items and a handful of dangerous goods. Rules are set per country and checked by each airport, so this guide gives the rules for Thailand, the United States and the United Kingdom, with the source for each.

Liquids in your cabin bag

Thailand: each container may hold at most 100 ml (the size of the container counts, not how full it is). All containers go in one clear, resealable plastic bag of up to 1 litre, one bag per passenger, shown separately at security. Milk and food for babies and medicine are allowed in reasonable amounts. Liquids bought in the airport's duty-free shops or on board must stay in the sealed bag with the receipt from that day. The Civil Aviation Authority of Thailand (CAAT) has applied these rules since 1 June 2007.

United States: the TSA's 3-1-1 rule is the same in practice: containers of 3.4 oz (100 ml) or less in one quart-sized bag. Medicine and food for babies and children are exempt.

United Kingdom: at most airports the limit is still 100 ml per container. Some airports with newer scanners accept containers of up to 2 litres, but it depends on the airport, so check the one you leave from, any airport where you change planes, and your return airport. Where a bag is needed it holds up to 1 litre (about 20 by 20 cm). Medicine, special dietary food and baby food are allowed up to 2 litres per container at all UK airports. Frozen liquids are not allowed in hand luggage.

Bigger bottles, such as full-size shampoo or a bottle of sunscreen, can go in your checked luggage.

Power banks: Thailand's rules since June 2026

In June 2026 Thailand tightened its rules for power banks with CAAT Regulation No. 122 on carrying lithium batteries on aircraft. For flights from and within Thailand:

• Cabin only: power banks are not allowed in checked luggage.
• At most 2 power banks per passenger.
• Size: up to 100 Wh (about 20,000 mAh) without approval. From 100 to 160 Wh you need the airline's approval first. Power banks above 160 Wh are not allowed on board at all, according to Airports of Thailand.
• The rating must be printed on it. A power bank without a clear Wh rating can be refused.
• No charging on board: you may not charge the power bank during the flight, or use it to charge your phone or other devices.
• Keep it with you: in the seat pocket or on your person, not in the overhead bin.

The US rule is simpler: power banks must be in carry-on bags and are not allowed in checked bags. Individual airlines (in Asia especially) add their own limits on using power banks during the flight, so check your airline too.

Spare batteries, phones, laptops and cameras

• Spare lithium batteries (loose batteries for phones, laptops or cameras) go in your cabin bag only, with the contacts protected, for example in their own pouch or with tape over the ends. CAAT allows up to 20 per passenger: lithium-ion up to 100 Wh each, lithium metal with up to 2 g of lithium each.
• Devices with the battery inside (phone, laptop, tablet, camera) can travel in the cabin or in checked luggage, up to 15 devices per person. If you check one in, switch it off completely and protect it from damage.
• Ordinary AA and AAA batteries (alkaline, NiMH) are not restricted.

E-cigarettes, lighters and matches

• E-cigarettes and vapes: cabin bag or on your person only, never in checked luggage, and you may not use or charge them on board. Note that e-cigarettes are illegal in Thailand, so don't bring them into the country.
• Lighters: one ordinary lighter, carried on your person. Torch (blue-flame) lighters are not allowed at all.
• Matches: one book or box of safety matches, on your person.

Knives, scissors and tools

Rules for sharp items differ by country and are decided by the security officer on the day. The US rules, as an example: knives are not allowed in carry-on bags, except plastic cutlery and round-bladed butter knives. Scissors are allowed in the cabin if the blades are less than 4 inches (about 10 cm) from the pivot point. Everything else that is sharp goes in checked luggage, wrapped or sheathed so it can't hurt the baggage handlers.

Food

Solid food is fine in both cabin and checked bags. Soft or liquid food, such as sauces, soups, yoghurt or jam, counts as a liquid at security, so in your cabin bag it has to follow the 100 ml rule. Taking meat, dairy, fruit or plants into another country is a customs question, separate from airport security: check the rules of the country you land in.

Alcohol, aerosols and other dangerous goods

• Alcohol: drinks between 24% and 70% alcohol are allowed in checked luggage in unopened retail packaging, up to 5 litres per passenger. Drinks above 70% are not allowed. In your cabin bag, alcohol counts as a liquid.
• Toiletry aerosols (hairspray, deodorant): up to 500 ml per can and 2 litres in total per person in checked luggage; in your cabin bag the 100 ml rule applies.
• Never allowed: fireworks and flares, flammable aerosols that are not toiletries, fuel, and electroshock weapons.

Cabin bag or checked luggage?

Check your airline

Airport security decides what passes the checkpoint, but your airline decides what it carries, and some airlines are stricter, especially about power banks. Before you pack, read your airline's baggage page. Flying from Thailand? See the airport pages for Suvarnabhumi and Don Mueang, and Before you fly for the visa and entry forms for your trip.

Rules change, and the security officer on the day has the final say. The sources for this guide are listed below.