Korean -(으)ㄹ 수 있다 / 없다: How to Say “Can” and “Cannot”

If you want to say “I can speak Korean,” “I can’t go today,” or “Can you come tomorrow?”, one of the most useful Korean grammar patterns is -(으)ㄹ 수 있다 / 없다.

This pattern is often introduced simply as “can” and “cannot.” That is a useful starting point, but it does more than describe a skill. In everyday Korean, it can also tell you whether something is possible in a particular situation.

In this guide, we will look at how to form -(으)ㄹ 수 있다 / 없다, when Koreans actually use it, how it differs from 못, and what to say when you are asking for permission rather than ability or possibility.

1. What Does -(으)ㄹ 수 있다 / 없다 Mean?

The basic meanings are:

-(으)ㄹ 수 있다 = can / be able to / it is possible to
-(으)ㄹ 수 없다 = cannot / be unable to / it is not possible to

For example:

한국어를 읽을 수 있어요.
I can read Korean.
오늘 갈 수 없어요.
I can’t go today.
내일 만날 수 있어요?
Can you meet tomorrow?

The first sentence is mainly about ability. The second and third can be about circumstances or possibility.

That distinction is useful because English uses can for several different ideas, and Korean does not always express all of them in exactly the same way.

2. How the Pattern Is Formed

Take the verb stem and add -ㄹ 수 있다 or -을 수 있다.

Verb stem	Pattern	Example
Ends in a vowel	-ㄹ 수 있다	가다 → 갈 수 있어요
Ends in a consonant	-을 수 있다	먹다 → 먹을 수 있어요
하다 verbs	할 수 있다	공부하다 → 공부할 수 있어요

More examples:

보다 → 볼 수 있어요 — can see/watch
읽다 → 읽을 수 있어요 — can read
만나다 → 만날 수 있어요 — can meet
운전하다 → 운전할 수 있어요 — can drive

One spacing point is worth remembering: write 할 수 있어요, not 할수 있어요. The dependent noun 수 is written separately.

3. How to Say “Cannot”

To make the negative form, change 있다 to 없다.

갈 수 있어요 → 갈 수 없어요
먹을 수 있어요 → 먹을 수 없어요
운전할 수 있어요 → 운전할 수 없어요

For example:

오늘은 시간이 없어서 만날 수 없어요.
I can’t meet today because I don’t have time.

Here, the speaker has not lost the ability to meet someone. The circumstances make the meeting impossible.

This is why it is better to understand -(으)ㄹ 수 있다 / 없다 as a pattern for both ability and possibility, rather than memorizing it only as “can/cannot.”

4. Talking About Ability

Use this pattern when talking about something a person is capable of doing.

수영할 수 있어요.
I can swim.
한국어를 조금 말할 수 있어요.
I can speak a little Korean.
운전할 수 있어요?
Can you drive?
한글을 읽을 수 있어요.
I can read Hangul.

These examples describe a skill or ability that someone has.

5. Talking About What Is Possible

The same grammar is very commonly used when circumstances determine whether an action is possible.

내일 올 수 있어요?
Can you come tomorrow?
지금은 들어갈 수 없어요.
You can’t go in right now.
여기에서 카드로 결제할 수 있어요.
You can pay by card here.
오늘은 예약할 수 없어요.
It isn’t possible to make a reservation today.

This use is particularly useful when you are in Korea. You may need it when asking about payments, transportation, reservations, opening hours, or whether a service is available.

6. “Can I...?”: Possibility or Permission?

English speakers often use Can I...? to ask for permission. Korean makes a useful distinction here.

You can ask:

여기에서 사진을 찍을 수 있어요?
Is it possible to take photos here?

But if your real question is whether taking photos is allowed, a more direct expression is:

여기에서 사진을 찍어도 돼요?
Is it okay if I take photos here?

Another example:

여기 앉을 수 있어요? — Is it possible for me to sit here?
여기 앉아도 돼요? — Is it okay if I sit here?

In real situations, the meanings can overlap. However, -아/어도 돼요? focuses more directly on permission, while -(으)ㄹ 수 있어요? naturally asks about ability or possibility.

This is a useful distinction because translating every English Can I...? literally with -(으)ㄹ 수 있어요? can sometimes sound less natural than choosing the expression that matches what you actually want to ask.

7. -(으)ㄹ 수 없다 vs 못

Koreans also use 못 very frequently to say that someone cannot do something.

Compare:

오늘 갈 수 없어요.
오늘 못 가요.

Both can mean:

I can’t go today.

But the two forms are not always identical in feeling.

-(으)ㄹ 수 없다

This form explicitly presents an action as not possible or beyond someone’s ability under the circumstances.

오늘은 시간이 없어서 갈 수 없어요.
I can’t go today because I don’t have time.

못 + verb

못 is extremely common in everyday conversation. It is often a shorter and more conversational way to say that someone cannot do something.

오늘 못 가요.
I can’t go today.

Consider another example:

매운 음식을 못 먹어요.
I can’t eat spicy food.

Depending on the context, this might mean that the speaker cannot tolerate spicy food.

Now compare:

지금은 매운 음식을 먹을 수 없어요.
I can’t eat spicy food right now.

Here, the situation may be preventing the speaker from eating it.

Context matters, so it is better to learn both forms through real sentences rather than assuming that they are mechanically interchangeable every time.

8. Useful Examples in Korea

Here are some sentences that are useful beyond a grammar exercise.

Payment

외국 카드로 결제할 수 있어요?
Can I pay with a foreign card?

Transportation

여기에서 티머니를 살 수 있어요?
Can I buy a T-money card here?

At a restaurant

지금 주문할 수 있어요?
Can I order now?

이거 포장할 수 있어요?
Can I get this to go? / Is takeout possible?

Making plans

토요일에 만날 수 있어요?
Can you meet on Saturday?

오후에는 만날 수 없어요.
I can’t meet in the afternoon.

Learning Korean

한글을 읽을 수 있어요.
I can read Hangul.

아직 한국어를 빨리 말할 수 없어요.
I still can’t speak Korean quickly.

9. A Natural Short Dialogue

A: 내일 같이 점심 먹을 수 있어요?
Can you have lunch with me tomorrow?

B: 네, 점심에는 만날 수 있어요. 그런데 저녁에는 못 만나요.
Yes, I can meet at lunchtime. But I can’t meet in the evening.

A: 그럼 한 시에 만날까요?
Then shall we meet at one?

B: 좋아요.
Sounds good.

Notice that the speaker naturally uses both 만날 수 있어요 and 못 만나요. Real Korean does not require you to repeat the same grammar pattern in every sentence.

10. Common Mistakes

1. Forgetting -을 after a consonant

❌ 먹 수 있어요
✅ 먹을 수 있어요

2. Conjugating 없다 incorrectly

❌ 갈 수 없다요
✅ 갈 수 없어요

3. Writing 수 together with the previous word

❌ 할수 있어요
✅ 할 수 있어요

4. Combining 못 and -(으)ㄹ 수 없다 unnecessarily

❌ 더 이상 못 먹을 수 없어요.

If you mean “I can’t eat anymore,” say:

✅ 더 이상 못 먹어요.
or
✅ 더 이상 먹을 수 없어요.

5. Using -(으)ㄹ 수 있어요? for every English “Can I...?”

First ask yourself what you mean:

Is it possible? → -(으)ㄹ 수 있어요?
Is it allowed? → -아/어도 돼요?

11. Quick Reference

Meaning	Korean
I can do it	할 수 있어요
I cannot do it	할 수 없어요
I can’t do it (common in speech)	못 해요
Can you come?	올 수 있어요?
Is it okay if I do it?	해도 돼요?

12. Quick Practice

1. How would you say “I can read Korean”?

Show answer

한국어를 읽을 수 있어요.

2. How would you say “I can’t go today”?

Show answer

오늘 갈 수 없어요.
In everyday conversation, 오늘 못 가요. is also very natural.

3. Complete the sentence.
먹다 → ______ 수 있어요.

Show answer

먹을 수 있어요.

4. Which sentence asks more directly for permission?

A. 여기 앉을 수 있어요?
B. 여기 앉아도 돼요?

Show answer

B. 여기 앉아도 돼요? asks more directly whether sitting there is allowed.

13. Related Korean Grammar

If you are building your Korean grammar step by step, these guides are useful next:

Korean -아/어야 돼요: Saying “Have To” and “Must” — for obligations and things you need to do
Korean Particles: 은/는, 이/가 and 을/를 — for understanding how basic Korean sentences are structured

Final Takeaway

The most useful way to remember -(으)ㄹ 수 있다 / 없다 is not simply “can/cannot.” Think of it as a way to talk about whether someone has the ability to do something or whether an action is possible in the situation.

Start with these three sentences:

한국어를 읽을 수 있어요. — I can read Korean.
오늘은 갈 수 없어요. — I can’t go today.
내일 만날 수 있어요? — Can you meet tomorrow?

Then pay attention to 못 in real conversations. You will hear it often, and learning when Koreans naturally choose 못 instead of -(으)ㄹ 수 없다 will make your Korean sound much more natural.