을/를: Object particle

을/를: the object particle, and where it hides

Picking the right one

The mechanical rule is the easy half, and it's the same shape as every other Korean particle pair.

• 을 after a noun ending in a consonant: 책을 chaeg-eul, "book"
• 를 after a noun ending in a vowel: 영화를 yeonghwa-reul, "movie"

That's it. The particle marks the thing the verb happens to.

The difference between 를 and 은 in Korean

Once the object particle itself makes sense, this is the pair that starts causing trouble. Both can follow the same noun, and English shows no difference at all, but they are doing separate jobs.

를 marks the thing the verb acts on. 은 marks what the sentence is about, and usually hints at a contrast.

• 책을 읽어요. chaeg-eul ilgeoyo — "I read a book." 을 points at what gets read.
• 책은 읽어요. chaeg-eun ilgeoyo — "The book, I do read." 은 sets the book up as the topic, and quietly suggests there's something else you don't read.

So 을/를 answers "what did the verb happen to", and 은/는 answers "what are we talking about".

Verbs that take an object when English doesn't

A handful of Korean verbs often mark their target with 을/를, even though English makes you expect "with" or "to". These are worth memorizing as pairs. You'll also hear 친구와 만나요 chinguwa mannayo, 버스에 타요 beoseue tayo and 학교에 다녀요 hakgyoe danyeoyo, which are just as correct.

• 친구를 만나요. chingu-reul mannayo — "I meet a friend."
• 버스를 타요. beoseu-reul tayo — "I take the bus."
• 학교를 다녀요. hakgyo-reul danyeoyo — "I attend school."

Movement verbs do something similar with paths and places:

• 길을 걸어요. gir-eul georeoyo — "I walk along the street."
• 다리를 건너요. dari-reul geonneoyo — "I cross the bridge."

The street isn't being acted on the way a book is, but Korean treats the path as the object anyway.

It disappears in speech

In casual conversation the object particle drops constantly, because the verb usually makes the roles obvious.

• 밥 먹었어? bap meogeosseo? — "Did you eat?" Among friends this sounds more natural than 밥을 먹었어 babeul meogeosseo, though both are fine.

It comes back the moment there's any risk of confusion, or when you want to lean on the object specifically. There's a whole post about when particles vanish if that habit interests you.

And it gets replaced

을/를 never goes in front of 도 or 만. 도 replaces it outright, and 만 can take it back afterwards for emphasis (책만을 chaengmaneul, mostly in writing), but never before:

• 책을 chaegeul + 도 → 책도 chaek-do, "the book too". Never 책을도 chaegeuldo.
• 책을 chaegeul + 만 → 책만 chaengman, "only the book". Never 책을만 chaegeulman.

Going on a trip, going shopping

가다 gada · to go normally takes 에 e for the place. But when the noun is an activity rather than a place, it takes 을/를:

• 여행을 가요. yeohaengeul gayo "I'm going on a trip."
• 쇼핑을 갔어요. syopingeul gasseoyo "I went shopping."
• 등산을 가요. deungsaneul gayo "I'm going hiking."

The place still keeps 에, so both can sit in one sentence:

• 제주도에 여행을 가요. jejudoe yeohaengeul gayo "I'm going on a trip to Jeju."

On lengths of time

You'll sometimes see 을/를 on an amount of time. Without it the sentence is neutral. With it, the time sounds long:

• 한 시간 기다렸어요. han sigan gidaryeosseoyo "I waited an hour."
• 한 시간을 기다렸어요. han siganeul gidaryeosseoyo "I waited a whole hour."

You don't need to produce this one, but it explains why the particle pops up in places that don't look like objects.