Indicates movement from outside to inside
When to use
Outside to inside building, Outside to inside room, From street into building or room
The nuance
Used when the speaker or reference point is outside, and the subject moves inside.
들어가다 (deul-eo-ga-da, deuleogada) · 들어오다 (deul-eo-o-da, deuleooda)
들어가다 is used when moving from outside to inside, while 들어오다 is used when entering a space where the speaker or reference point is located.

One lane per word — no nested boxes, just the gist.
Indicates movement from outside to inside
When to use
Outside to inside building, Outside to inside room, From street into building or room
The nuance
Used when the speaker or reference point is outside, and the subject moves inside.
Indicates movement into a space where the speaker or reference point is located
When to use
Into room where speaker is, Into office interior, Into home interior
The nuance
Used when the speaker or reference point is inside, and the subject moves into that space.
그는 집에 들어갔다.
geu-neun jip-e deul-eo-gass-da., geu neun jip e deul eo gass da.
The speaker is outside the house, and he moves inside, so 들어가다 is appropriate.
그는 집에 들어왔다.
geu-neun jip-e deul-eo-wass-da., geu neun jip e deul eo wass da.
The speaker is inside the house, and he enters inside, so 들어오다 is appropriate.
나는 방에 들어갔다.
na-neun bang-e deul-eo-gass-da., na neun bang e deul eo gass da.
The speaker is outside the room and moves inside, so 들어가다 is used.
나는 방에 들어왔다.
na-neun bang-e deul-eo-wass-da., na neun bang e deul eo wass da.
The speaker is outside the room, so 들어오다 is inappropriate as it requires the speaker inside.
고객이 사무실에 들어왔다.
go-gaek-i sa-mu-sil-e deul-eo-wass-da., go gaek i sa mu sil e deul eo wass da.
The speaker is inside the office, and the customer enters inside, so 들어오다 is correct.
고객이 사무실에 들어갔다.
go-gaek-i sa-mu-sil-e deul-eo-gass-da., go gaek i sa mu sil e deul eo gass da.
들어가다 is only appropriate if the speaker is outside the office; here the speaker is inside, so it's wrong.
나는 학교에 들어갔다.
na-neun hak-gyo-e deul-eo-gass-da., na neun hak gyo e deul eo gass da.
The speaker is outside the school and moves inside, so 들어가다 is correct.
나는 학교에 들어왔다.
na-neun hak-gyo-e deul-eo-wass-da., na neun hak gyo e deul eo wass da.
If the speaker is not inside the school, 들어오다 cannot be used.
Which is correct when the speaker is outside the room?
When the speaker is inside the house and a guest enters, which is correct?
Which verb is used when entering a building from the street?