Hongdae runs late, and for luggage storage the station under it — Hongik Univ. — is one of the most useful in the city. Two reasons: it has a lot of lockers, and the AREX airport line stops here.
Coin lockers — 5 spots, about 171 units
The lockers sit in 5 spots totalling about 171 units, near exits 2, 3 and 8. For scale, Seoul Station has 4 spots and about 72 units on the same measure — Hongdae holds more than twice as many, so one bank being full leaves you real options.
Pricing is the network standard: ₩2,200 small, ₩3,300 medium, ₩4,400 large for the first four hours, then ₩500 / ₩800 / ₩1,000 per extra hour. The Hongdae locker page lists each spot with live availability by size, so check before you commit.
Why Hongdae is handy for the airport
Hongik Univ. is an interchange for Line 2, the Gyeongui-Jungang line and the AREX. Since the airport line stops here, the clean last-day move is to store the suitcase in the morning, spend the day around Hongdae and Yeonnam-dong, then pull the bag and step onto the Incheon train. No hauling it across town to Seoul Station first.
The staffed desk started here
Seoul's staffed T-Luggage service began at Hongik Univ. in November 2019, and now also runs at Seoul Station, Gimpo Airport, Myeongdong, Gangnam and Jamsil. Staff take the bag at a counter and the service ships to hotels and the airport — the move when your case won't fit a large locker (50 × 90 × 60 cm inside) or you have several.
Late nights and pickups
Hongdae's nightlife outlasts the lockers. They run roughly 05:00 to midnight, and outside that window you cannot collect — so pull your bag before midnight if you plan to stay out. Past your paid block, the door opens only after you settle the extra charge. New to the machines? The how-to for foreigners covers payment.
Sources: City of Seoul official guidance (T-Locker / T-Luggage) for fares, dimensions and the staffed-desk stations. Spot counts, unit counts, exits and live availability come from Seoul Open Data records.