Carry-on Liquids and Gels: The 100ml Rule at Korean, Japanese, and Taiwanese Airports
The security checkpoints for international departures at Incheon, Narita, and Taoyuan all use the same basic framework: each individual container must hold 100ml or less, and each passenger is allowed one 1L clear zip-top bag. That said, the exact bag dimensions, how the 100ml limit is judged (it's based on the printed capacity of the container, not how much liquid is actually left inside), and how duty-free items are handled differ slightly from airport to airport, and these differences can lead to confiscation when a connecting flight is involved.
The shared framework: 100ml, 1L, one bag per person
All three airports apply the same three principles at international departure security screening.
- Each liquid, gel, or spray container must have a capacity of 100ml or less. Even if a container only has 50ml left in it, if the container itself is labeled as 150ml, it cannot be brought through. The judgment is based on the container's printed capacity, not the remaining amount.
- These containers must all be placed inside a single, clear, resealable 1L or smaller zip-top bag, sealed, and presented for inspection.
- Only one zip-top bag is allowed per passenger.
Incheon Airport states that even a bag that isn't fully sealed will be treated as not permitted, and Taoyuan Airport likewise specifies that if a container itself is larger than 100ml, even if the contents inside are less than that, it must either be checked as hold luggage or discarded before the screening point.
Detailed comparison by airport
| Category | Korea (Incheon) | Japan (Narita) | Taiwan (Taoyuan) |
|---|---|---|---|
| Container limit | 100ml or less (printed container capacity) | 100ml or less (printed container capacity) | 100ml or less (container capacity, total 1L or less) |
| Zip-top bag size | 1L, clear bag measuring 20.5cm x 20.5cm or 15cm x 25cm | 1L or less, clear resealable bag roughly 20cm x 20cm per side, or with combined length and width of 40cm or less | 1L (1000cc) or less, clear zip-top bag roughly 20cm x 20cm |
| Bags per person | 1 | 1 | 1 |
| Applies to domestic flights | Not applied (domestic routes such as Gimpo to Jeju have relaxed liquid rules, though hazardous materials and flammable sprays are still restricted) | Not applied (under JAL's domestic flight rules, though hazardous items such as paint, adhesives, and bleach are separately prohibited) | No separate domestic rule was confirmed in this research |
At all three airports, if you haven't prepared a zip-top bag in advance, you can buy one at a convenience store inside the terminal. Incheon Airport notes that these are sold at the convenience stores on the third floor of Terminals 1 and 2.
Exceptions: medication and baby food
All three airports make separate exceptions for medication and baby food, though the documentation requirements differ by airport.
- Incheon Airport: If liquid medication exceeds 100ml, you must carry a doctor's note or prescription in Korean and English. If traveling with an infant or toddler aged six or under, the amount of baby food, formula, water, or juice needed during the flight is exempted even if it exceeds 100ml, and it should simply be presented separately at the security check.
- Narita Airport: Medication, infant milk and baby food, and special dietary items are excluded from the 100ml rule. However, screening staff may ask for evidence that the medication is needed on board (such as a prescription), and for baby food, only the amount needed during the flight is permitted when traveling with a child, and it must be separated from other baggage and presented to screening staff.
- Taoyuan Airport: The stated principle is only that passengers must inform screening staff in advance if they are carrying medication, medical liquids, gels, or sprays that exceed the 100ml rule; specific documentation requirements could not be confirmed. For prescription medication crossing borders, it is safer to check the departure and arrival countries' rules in advance and carry a bilingual prescription.
Duty-free STEB sealed bags and connecting-flight precautions
At all three airports, liquids purchased at duty-free shops are allowed regardless of the 100ml rule, as long as they remain sealed together with the receipt in a STEB (Security Tamper Evident Bag). The catch is that this only holds as long as the bag remains unopened until you reach your final destination airport.
- Incheon Airport: The item must be placed in a duty-free sealed bag and remain unopened until boarding the flight to your final destination for the volume exemption to apply. When connecting through an airport overseas, that country's security rules may differ, which could require you to surrender the item or have it confiscated, so it's advised to check the connecting country's rules with the airline or travel agency in advance.
- Narita Airport: STEBs were introduced starting October 27, 2015, allowing passengers departing Narita and connecting at an overseas airport to purchase liquids such as alcohol and cosmetics at duty-free shops. However, if the bag is opened before passing through security at the connecting airport, that liquid can no longer pass the next security check from that point on, and depending on the country or region, STEBs themselves may not be recognized, meaning the item may need to be voluntarily discarded at the connecting airport.
- Taoyuan Airport: Passengers connecting to a third country who purchase duty-free items should inform store staff of their connecting flight schedule in advance so that packaging, receipt, and sealing requirements can be confirmed beforehand. STEBs are not a universally accepted pass everywhere, so if the connecting airport's rules are stricter, or if the bag has been opened, or the receipt is incomplete, the item may fail to pass the next security check.
In practical terms, if you plan to buy alcohol or cosmetics in Korea and travel on to a third country via Japan or Taiwan, the only reliable approach is to tell the duty-free staff your final connecting airport at the time of purchase and confirm whether that airport accepts STEBs.
Reference: Incheon International Airport, liquid carry-on rules
Reference: Incheon International Airport, prohibited carry-on items guide (FAQ)
Reference: Narita International Airport, international flight liquid restrictions guide (Korean)
Reference: Narita International Airport, STEBs introduction notice (October 2015)
Reference: Japan Airlines (JAL), notice on liquid restrictions on board aircraft
Reference: Taoyuan International Airport, passenger baggage rules (客運行李攜帶規定)
Reference: Taoyuan International Airport, transfer security screening (轉機安檢) guide