Incheon Airport's 100ml Liquid Rule and Zip Top Bag Sizes: What Confuses Transfer Passengers From Japan and Taiwan
The Incheon International Airport Corporation's official page limits liquids carried on international flights to 100ml or less per container and instructs passengers to pack the full amount into one clear zip top bag per person. The official page lists two bag sizes: 20.5cm by 20.5cm, or 15cm by 25cm. Narita Airport also allows a 1L zip top bag, but its official page gives different numbers: 20cm by 20cm, or a combined length and width of about 40cm. Travelers departing from Japan or Taiwan and transferring at Incheon should check both airports' size requirements and the handling procedure for duty free liquids during transfer, so they can avoid repacking their bags.
Incheon Airport zip top bag rules: 100ml containers and 20.5cm or 15cm dimensions
The Incheon International Airport Corporation's official page limits liquid, spray, and gel items, including cosmetics, toiletries, and medicines, to 100ml or less per container. Passengers may pack the full quantity into only one clear plastic zip top bag per person. The Incheon International Airport Corporation's carry on allowance page lists the bag dimensions as 20.5cm by 20.5cm or 15cm by 25cm. Domestic flight segments are not subject to this rule.
Size differences from Narita Airport's zip top bag
Narita Airport's official page gives different numbers for its bag dimensions. A square bag must measure 20cm or less on each side. A rectangular bag passes if the combined length and width comes to about 40cm or less. A 24cm by 17cm bag, whose sides add up to 41cm, falls within this range.
| Airport | Square dimensions | Rectangular dimensions | Capacity |
|---|---|---|---|
| Incheon Airport | 20.5cm by 20.5cm | 15cm by 25cm | 1L |
| Narita Airport | 20cm by 20cm | Combined length and width of about 40cm | 1L |
Both airports allow only one zip top bag per person, and the bag must be fully sealed and placed in a tray to pass security. The Narita Airport international liquid restriction guide lists both size conditions together.
Duty free liquids during Incheon transfer: STEB bags and receipts
Korean Air's Incheon Airport transfer guide page states the handling procedure for liquids over 100ml purchased at other airports or on board. Such liquids pass security and board the aircraft only when sealed in a Security Tamper Evident Bag (STEB, 훼손탐지가능봉투) provided by the duty free shop, together with the receipt. If the bag is opened or damaged before boarding, the item is refused for carry on. The same page states that passengers transferring from an Incheon international flight to a domestic flight to Busan or Daegu cannot use the Incheon Airport duty free shops. On this route, passing through immigration blocks domestic flight boarding, so passengers must follow the transfer signs and use the designated route.
100ml and 1L baggage rules for flights departing Taiwan
Many flights departing Taoyuan Airport and connecting through Incheon follow the airline's own international baggage rules. Cathay Pacific's official baggage guide page limits liquids, aerosols, and gels to 100ml or less per container, and instructs passengers to pack the full amount into one resealable clear bag of 1L or less. The same page states that prescription medicine, baby food, and breast milk may exceed 100ml and still be carried on if presented for inspection at security.
Ministry of Land, Infrastructure and Transport Notice No. 2021-864 and the authority of the security screening supervisor
The Ministry of Land, Infrastructure and Transport policy information page states that, under Notice No. 2021-864 (operating standards for substances prohibited from carry on aboard aircraft), liquids, sprays, and gels exceeding 100ml per container are prohibited from carry on on international departure flights and on transfer or transit flights. This notice applies to international departure flights and transfer or transit flights. Domestic flight segments are excluded from this rule. The same guidance includes a provision allowing the security screening supervisor to separately prohibit the carry on of any substance judged to pose a possible hazard during screening. Even a zip top bag that meets both the size and capacity conditions can still be refused under this judgment.
Sources: Incheon International Airport Corporation, carry on allowance standards
Sources: Narita Airport, international liquid carry on restriction guide
Sources: Korean Air, Incheon Airport transfer (domestic to international) guide
Sources: Cathay Pacific, liquids, aerosols, and gels baggage rules