을 vs 를 (eul vs reul): the Korean object marker, and when Koreans drop it

It is 2 AM. You and a friend are looking at the instant noodles in a 편의점 [펴니점] (pyeonuijeom) — a convenience store.

Your friend asks: 뭘 먹을까? [뭘 머글까?] (mwol meogeulkka?) — "What should we eat?" This 뭘 is a short form of 뭐를 ("what" + 를).

How do I choose 을 or 를?

Look at the last block of the word. Does it have a 받침 (batchim)? A 받침 is a consonant at the bottom of the block.

• Ends in a consonant → 을
• Ends in a vowel → 를

In casual speech, 를 after a vowel often becomes just ㄹ: 뭐를 → 뭘, 나를 → 날 (me), 너를 → 널 (you). This is the 뭘 from the convenience store.

Which verbs need an object?

These are verbs where you do something to something. In English, if you can ask "what?" after the verb, it usually uses 을/를 in Korean.

Two verbs often surprise English speakers:

• 친구를 만나요 (chingureul mannayo) — "I meet a friend." English can say "meet with". But in Korean, the friend is a normal object.
• 버스를 타요 (beoseureul tayo) — "I take the bus." In Korean, the bus is the object of "ride".

When Koreans drop 을/를

Many textbooks don't say this clearly: in relaxed talk, Koreans leave out 을/를 very often. The situation makes the meaning clear.

If you add the particle, it puts more focus on the object. 밥을 먹었어? sounds more like "Did you eat a real meal?" Maybe your friend only eats snacks.

Drop it with friends. Keep it in writing, on tests and in careful polite speech.

Easy mistakes

Almost every learner makes this mistake: 좋아요 vs 좋아해요.

• 좋다 [조타] (jota) — "to be good" or "to be liked" — is a describing word (an adjective). The thing you like is the subject, so it uses 이/가.
• 좋아하다 [조아하다] (joahada) — "to like" — is an action verb. The thing you like is the object, so it uses 을/를.

Both sentences mean "I like coffee." Check your pairs:

• Wrong: 커피를 좋아요, 커피가 좋아해요. The pairs don't match.
• Right: 커피가 좋아요, 커피를 좋아해요. The pairs match.
• The same for "dislike": 싫어요 (sireoyo) uses 이/가, and 싫어해요 (sireohaeyo) uses 을/를.

Some more:

• 필요하다 (to need) uses 이/가: 돈이 필요해요 ("I need money"), not 돈을 필요해요.
• 있다 / 없다 (to have / not have) use 이/가: 시간이 없어요 ("I don't have time").
• 하다 verbs can split. 공부하다 → 공부를 해요 is fine and common. But don't use two objects: 한국어를 공부를 해요 sounds strange. Say 한국어를 공부해요 ("I study Korean").
• Wrong form: 커피을, 밥를. Check the 받침.

Why can Koreans drop it?

English uses word order to show who did what. "The cat ate the fish" is different from "The fish ate the cat." Korean uses small markers instead, so the word order can change.

But in real talk, the situation already shows who is eating what. So the marker is not needed, and casual speech drops it.

This is also why 밥 먹었어? feels so warm. It is short and relaxed. Koreans use it to say "I care about you" without saying it directly. With 을, it sounds more like a check-up and less friendly.

Quick check

1. 사과___ 먹어요. (I eat an apple.) → 과 has no 받침: 사과를
2. 저는 강아지___ 좋아요. (I like puppies.) → 좋다 is a describing word: 강아지가
3. 저는 강아지___ 좋아해요. → 좋아하다 is an action verb: 강아지를