9 Ways to Say Can and Can't in Korean: -(으)ㄹ 수 있다/없다

Quick answer: To say "can" in Korean, add -(으)ㄹ 수 있다 (-(eu)l su itda) to a verb stem; for "can't," use -(으)ㄹ 수 없다 (-(eu)l su eopda). So 가다 (to go) becomes 갈 수 있어요 ("I can go") and 먹다 (to eat) becomes 먹을 수 없어요 ("I can't eat it"). In everyday speech, Koreans often shorten the negative to 못 + verb: 못 가요.

The one idea to walk away with: **-(으)ㄹ 수 있다 is about whether something is possible** — your skill, your schedule, the rules, the circumstances. It is not a feeling and not a wish. Once you hear it that way, the whole family of 수 expressions opens up.

The form, in ten seconds

Irregulars behave as usual: 듣다 → 들을 수 있어요, 돕다 → 도울 수 있어요, 짓다 → 지을 수 있어요.

Two things learners get wrong before they even open their mouth. First, spacing: it is 할 수 있어요, three chunks, never 할수있어요. Second, pronunciation: 수 hardens after ㄹ, so 할 수 있어요 sounds like [할 쑤 이써요]. If you say a soft [su], it sounds textbook-stiff.

1. 지금 갈 수 있어요.

지금 갈 수 있어요. — "I can go now."

This is the plain, neutral "can": nothing is stopping me. Use it for ability and for availability alike — 내일 올 수 있어요? ("Can you come tomorrow?") is one of the most-used questions in Korean office and friend life. If you need to be polite upward, the honorific goes inside: 내일 오실 수 있어요? — the -(으)시- honorific attaches to the verb stem, not to 있다.

2. 오늘은 못 가요.

오늘은 못 가요. — "I can't go today."

Spoken Korean prefers 못 to -(으)ㄹ 수 없다 for simple inability. 못 가요 is short, warm and normal; 갈 수 없어요 sounds heavier, a bit more written or final — the kind of thing you say when circumstances genuinely forbid it (오늘은 갈 수 없어요, 회의가 있어서요). Neither is wrong, but if a friend asks you out and you answer 갈 수 없어요, it lands slightly formal, like a notice rather than an apology.

Note 못 goes before the verb, and with 하다 verbs it splits: 수영 못 해요, 운전 못 해요.

3. 할 수 있어!

할 수 있어! — "You can do it!"

In 반말 with no subject, this is Korea's standard shout of encouragement — to a friend before an exam, to yourself in the mirror. Polite version: 할 수 있어요! For a more formal cheer, 할 수 있습니다! It pairs naturally with 응원할게요 and 파이팅. Notice that Korean leaves out "you" entirely here; that is normal, not lazy — see sentences that drop I and you.

4. 여기에서 사진 찍을 수 있어요?

여기에서 사진 찍을 수 있어요? — "Can I take pictures here?"

This asks whether it's possible — is there room, is it allowed, does it work. It's the right question at a museum counter or a café. If what you want is explicit permission from the person in front of you, 사진 찍어도 돼요? ("Is it okay if I take pictures?") is the more common choice. Koreans feel 수 있어요? as "is this possible?" and -아/어도 돼요? as "will you allow me?"

5. 수영할 줄 알아요.

수영할 줄 알아요. — "I know how to swim."

For a learned skill, Koreans often choose -(으)ㄹ 줄 알다 / 모르다 over 수 있다. 운전할 줄 몰라요 means "I never learned to drive"; 운전할 수 없어요 suggests something is blocking you right now (no license on you, a broken arm). Both are grammatical in many sentences, so this is a nuance, not a rule — but 한국어 할 줄 알아요? sounds more natural than 한국어 할 수 있어요? when you're asking about ability.

6. 비가 올 수도 있어요.

비가 올 수도 있어요. — "It might rain."

Add 도 and "can" becomes "might": -(으)ㄹ 수도 있다 = there's a possibility. 늦을 수도 있어요 ("I might be late") is a very useful hedge, softer than 늦어요. Koreans use it constantly to avoid sounding too certain, which is why it feels polite: you leave the other person room.

7. 어떻게 그럴 수 있어요?

어떻게 그럴 수 있어요? — "How could you do that?"

Same grammar, completely different job. Here 수 있다 carries reproach: the speaker is saying the act shouldn't even be possible for a decent person. You will hear this in arguments and in dramas when someone has been betrayed. If what you want is disbelief rather than blame, the usual lines are 그럴 리가 없어요 ("that can't be / there's no way") and 말도 안 돼요 ("no way"). Keep 어떻게 그럴 수 있어요? for real emotion — thrown into small talk, it sounds like you're starting a fight.

8. 올 수 있으면 오세요.

올 수 있으면 오세요. — "Come if you can."

수 있다 conjugates like any 있다 verb, so it stacks with other endings: -(으)면 (if), -아/어서 (so), -지만 (but). 시간이 없어서 갈 수 없었어요 — "I couldn't go because I had no time." Past tense lands on 있다/없다, not on the main verb: 갈 수 있었어요, never 갔을 수 있어요 for "I could go."

9. 제가 할 수 있는 건 다 했어요.

제가 할 수 있는 건 다 했어요. — "I did everything I could."

To put "can" in front of a noun, make 있다 a modifier with -는: 할 수 있는 일 ("work I can do"), 먹을 수 없는 음식 ("food I can't eat"), 믿을 수 없는 이야기 ("an unbelievable story"). This is where 수 있다 starts feeling like real Korean rather than a drill, and it's a good reason to get comfortable trying new verb endings out loud.

Two mistakes to avoid

Don't combine 못 and 수 없다. 못 갈 수 없어요 is a double negative that means almost nothing. Pick one: 못 가요 or 갈 수 없어요.

Don't use 수 있다 for "I want to." 갈 수 있어요 is "I'm able to go," not "I'd like to go." For wanting, you need 가고 싶어요.

FAQ

What does 할 수 있어요 mean in Korean?

할 수 있어요 means "I can do it" or "You can do it," depending on context, since Korean usually omits the subject. It's built from 하다 (to do) plus -(으)ㄹ 수 있다, the "can" pattern. Shouted as 할 수 있어! in 반말, it's the standard way to encourage someone.

What's the difference between 못 and -(으)ㄹ 수 없어요?

Both mean "can't," and both are correct. 못 + verb is shorter and much more common in conversation (못 먹어요, 못 가요), while -(으)ㄹ 수 없어요 sounds weightier and more formal, often pointing to circumstances that make something impossible. To a Korean ear, 못 가요 is a casual "I can't make it"; 갈 수 없어요 is closer to "I'm unable to attend."

How do you say "I can't speak Korean" in Korean?

한국어 못 해요 is what people actually say. 한국어 할 줄 몰라요 ("I don't know how to speak Korean") is also very natural because speaking a language is a learned skill. 한국어 할 수 없어요 is grammatical but sounds odd for language ability — save 수 없다 for situations, not skills.

Practice

Make each sentence with -(으)ㄹ 수 있다/없다, or choose the more natural option.

1. Say "I can make kimchi" politely (만들다, 김치를).
2. Say "I couldn't sleep yesterday" (어제, 자다) using 수 없다 in the past.
3. A friend asks you out tonight and you're busy. Which sounds more natural: 오늘은 못 가요 or 오늘은 갈 수 없어요?
4. Say "I might be a little late" (조금, 늦다).
5. Turn "food I can't eat" into a noun phrase (먹다, 음식).