For a straightforward packing plan, put the essential liquids and creams you need in hand luggage into appropriately small containers, then check the rules for every airport where you will pass through security. The size printed on the container can matter even when it is nearly empty.
Do this before buying a large toner in Korea. A bottle that fits beautifully into your bathroom routine may be awkward to bring home if you are travelling with cabin baggage only. A tax-refund receipt does not create an exception to airport liquids rules.
Container capacity is the important number
Incheon Airport's international departure guidance describes containers of no more than 100 ml, packed into one transparent, resealable bag of up to 1 litre per person. Its Korean FAQ makes the point particularly clearly: the container's capacity applies regardless of how much product remains.
That means a 200 ml toner bottle with a small amount left is not the same packing choice as a 50 ml travel bottle. Empty space inside the larger bottle does not turn it into a smaller container.
Treat creams, gels, cleansing oils and sunscreen as part of your liquids planning rather than looking only for products that pour like water. Keep the labels readable where possible, and do not assume a compact or packet is exempt just because it does not resemble a bottle.
Pack for the route, not the scanner you remember
Airport arrangements can differ by country, terminal and screening equipment. A relaxed experience on the outbound flight is not proof that the same container will be accepted at a connection or on the way home.
On my Korea–Europe trips, I usually put toiletries together in a zip bag inside checked luggage. For shorter trips within Europe when I take them in the cabin, I pay more attention to travel sizes and the resealable bag. Separating what I will carry on from what I will check in is the useful starting point for me. The applicable rules depend on the baggage and airports, though, rather than the flight distance.
Check the current official departure and transfer instructions close to travel. Airlines set baggage allowances, while security restrictions are another part of the journey; knowing that your bag is the right size does not settle the liquids question.
If you want a conservative packing plan for an itinerary with several airports, small clearly sized containers in a resealable bag reduce the need to rely on a special allowance at one stop. Confirm any exception before building the whole kit around it.
Samples and minis can save more work than decanting
Start by setting out what you will actually use during the trip. Cleanser, moisturiser and sunscreen may cover the everyday routine. Add a treatment because you use it, not because the suitcase creates an opportunity to bring every step.
A properly labelled mini can be easier than filling several anonymous pots. If you decant, use a clean, suitable container, label the contents and avoid leaving the product in it longer than necessary. Do not mix formulas together to save space. Keeping sunscreen in a suitable original travel size is a particularly simple option when available.
Close each container securely and test that the bag still seals. Place it where you can reach it for screening if the airport requires removal. A kit that only fits after forceful squeezing is unlikely to be pleasant to use when you need one item on the plane.
Leave space for the Korean shopping you have planned
If you expect to buy full-size products, decide in advance whether you will have checked baggage on the return journey. Put suitable sealed products in protective packaging and check both your airline's rules and any restrictions that apply to the particular product. Perfume and aerosols need more care than a casual assumption that everything can go in the hold.
Airport duty-free liquids can have special security-bag procedures, but buying a product tax-refunded in a downtown shop is a different transaction. Do not open a security bag or discard its receipt without understanding the transfer rules for your route.
Finally, keep purchases that may need tax-refund export verification accessible until you know the inspection procedure. Packing them at the very bottom of a checked case can create work at exactly the wrong time.
For a manageable travel kit, bring enough of the routine you know, keep the capacity clear and plan how the shopping will travel home. You can enjoy Korean beauty shopping without trying to make every new full-size bottle fit through hand-luggage security.