Can and Able -(으)ㄹ 수 있다 in Korean

In Brief

Attach -(으)ㄹ 수 있어요 to a verb stem to say that someone can do something: 갈 수 있어요 means “I can go.” Change 있어요 to 없어요 for “cannot”: 먹을 수 없어요 means “I cannot eat.” The same pattern can describe possibility, so 비가 올 수 있어요 can also mean “It may rain.”

Overview

Korean does not normally put a separate equivalent of English can before a verb. Instead, it turns the action into the pattern verb stem + -(으)ㄹ 수 있다. A verb stem (the basic part to which endings attach) is what remains when you remove -다 from the dictionary form: 가다 → 가-, 먹다 → 먹-, and 하다 → 하-.

This is a core A1 pattern because it lets you talk about practical abilities and options: speaking Korean, using a card, meeting tomorrow, or entering a room. In everyday polite conversation, you will most often hear -(으)ㄹ 수 있어요 and -(으)ㄹ 수 없어요. Korean often leaves the subject unspoken when the context makes it clear, so 갈 수 있어요 might mean “I can go,” “you can go,” or “they can go.”

The noun 수 refers to a way, means, or possibility. A literal reading of 갈 수 있어요 is therefore something like “a way to go exists,” but natural English simply uses “can go.” This helps explain why 있다 expresses availability and 없다 expresses its absence.

How It Works

Build the basic form

Remove -다 from the dictionary form and inspect the final sound of the stem.

Stem ending	Form to add	Dictionary form	Result	Meaning
Vowel	-ㄹ 수 있다	가다	갈 수 있다	can go
Consonant other than ㄹ	-을 수 있다	먹다	먹을 수 있다	can eat
ㄹ	- 수 있다	살다	살 수 있다	can live

With a vowel-ending stem, ㄹ becomes the final consonant of the preceding syllable: 가 + ㄹ → 갈 and 하 + ㄹ → 할. With a consonant-ending stem, add the full syllable 을: 먹 + 을 → 먹을. A stem already ending in ㄹ keeps that sound and does not take another one: 만들다 → 만들 수 있다.

The beginner procedure is:

1. Find the stem: 읽다 → 읽-.
2. Choose -ㄹ or -을: the stem ends in a consonant, so use -을.
3. Add 수 있다: 읽을 수 있다.
4. Make 있다 polite: 읽을 수 있어요.

Positive, negative, and question forms

Only the final 있다 or 없다 carries the conversational ending. The part before 수 stays unchanged.

Function	Plain dictionary style	Everyday polite style	Formal polite style
can	-(으)ㄹ 수 있다	-(으)ㄹ 수 있어요	-(으)ㄹ 수 있습니다
cannot	-(으)ㄹ 수 없다	-(으)ㄹ 수 없어요	-(으)ㄹ 수 없습니다
can …?	—	-(으)ㄹ 수 있어요?	-(으)ㄹ 수 있습니까?

In the everyday polite style, a statement and a question can have exactly the same written ending. In speech, context and rising question intonation distinguish them:

• 오늘 만날 수 있어요. — I can meet today.
• 오늘 만날 수 있어요? — Can you meet today?

Common stem changes

The -(으)ㄹ ending follows the same stem-change patterns found before other Korean endings beginning with a vowel or ㄹ. These forms are worth learning as whole units rather than forcing the basic rule mechanically.

Dictionary form	Ability form	Meaning	What happens
듣다	들을 수 있어요	can listen/hear	ㄷ changes to ㄹ
걷다	걸을 수 있어요	can walk	ㄷ changes to ㄹ
돕다	도울 수 있어요	can help	ㅂ changes to 우
짓다	지을 수 있어요	can build	ㅅ disappears
모르다	모를 수 있어요	may not know	르 is followed by ㄹ
만들다	만들 수 있어요	can make	final ㄹ remains

Not every verb with the same final letter is irregular. For example, 받다 → 받을 수 있어요 and 입다 → 입을 수 있어요 are regular. A dictionary or conjugation reference is useful when learning a new verb.

Ability and possibility

The construction covers two related ideas. Context tells you which one is intended.

• Ability or practical capacity: 민수 씨는 운전할 수 있어요. — Minsu can drive.
• Situational possibility: 오늘은 일찍 끝날 수 있어요. — It may finish early today.

English often separates these with can, may, might, or be possible. Korean can use the same pattern. With a human subject and a deliberate action, ability is usually the natural reading. With weather, events, or an uncertain outcome, possibility is more likely.

Past and future reference

Tense is marked on 있다/없다, not on the verb before 수.

Time	Form	Example	Translation
Present	-(으)ㄹ 수 있어요	지금 갈 수 있어요.	I can go now.
Past	-(으)ㄹ 수 있었어요	어제 갈 수 있었어요.	I could / was able to go yesterday.
Expected future ability	-(으)ㄹ 수 있을 거예요	다음 달에는 갈 수 있을 거예요.	I will probably be able to go next month.

The past negative is -(으)ㄹ 수 없었어요: 표가 없어서 들어갈 수 없었어요 means “I could not enter because I did not have a ticket.”

Spacing

Write 수 as a separate word:

• 할 수 있어요 — correct
• 할수 있어요 — incorrect

Here 수 is a dependent noun (a noun that normally appears with another form before it), so Korean spacing rules separate it from both the modifying verb and 있다/없다.

Examples in Context

Korean	English	Note
갈 수 있어요.	I can go.	Vowel stem: 가다 → 갈
한국어를 할 수 있어요.	I can speak Korean.	Literally “can do Korean”; a common way to describe language ability
매운 음식을 먹을 수 없어요.	I cannot eat spicy food.	Consonant stem and negative form
여기서 수영할 수 있어요?	Can I/we swim here?	Depending on context, this may ask about feasibility or permission
이 카드로 결제할 수 있어요?	Can I pay with this card?	A practical service question
저는 한글을 읽을 수 있지만 빨리 읽을 수는 없어요.	I can read Hangul, but I cannot read it quickly.	Contrasts a general ability with a limitation
오늘 저녁에 만날 수 있어요?	Can you meet this evening?	The subject is understood from context
다리가 아파서 오래 걸을 수 없어요.	I cannot walk for long because my leg hurts.	걷다 changes to 걸을
창문을 열 수 있어요?	Can you open the window?	Can be a question about ability or a contextual request
이 방에서는 와이파이를 사용할 수 있습니다.	Wi-Fi can be used in this room.	Formal style common in notices and explanations
내일 비가 올 수 있어요.	It may rain tomorrow.	Possibility rather than personal ability
계획이 바뀔 수 있어요.	The plan may change.	An uncertain event
어제는 너무 바빠서 전화할 수 없었어요.	I could not call yesterday because I was too busy.	Past inability
조금 더 연습하면 혼자 할 수 있을 거예요.	If you practice a little more, you will probably be able to do it alone.	Expected future ability

Common Mistakes

Adding the wrong form after a consonant

• Wrong: 먹ㄹ 수 있어요.
• Right: 먹을 수 있어요.
• Why: A stem ending in a consonant other than ㄹ takes -을. The shorter -ㄹ attaches only after a vowel-ending stem.

Doubling ㄹ

• Wrong: 살을 수 있어요.
• Right: 살 수 있어요.
• Why: When the stem already ends in ㄹ, do not add another 을/ㄹ for this pattern. Compare 살다 → 살 수 있다 and 만들다 → 만들 수 있다.

Conjugating the first verb as a polite verb

• Wrong: 가요 수 있어요.
• Right: 갈 수 있어요.
• Why: The first verb must use the modifier -(으)ㄹ, not the sentence-ending -아/어요 form. Politeness appears on 있어요.

Putting past tense on the first verb

• Wrong: 갔을 수 있어요 for “I was able to go.”
• Right: 갈 수 있었어요.
• Why: For past ability, keep 갈 수 and make 있다 past: 있었어요. The form 갔을 수 있어요 belongs to a more advanced possibility pattern and does not express ordinary past ability.

Forgetting the spaces around 수

• Wrong: 할수있어요.
• Right: 할 수 있어요.
• Why: The dependent noun 수 is written separately. In normal Korean orthography, all three parts are spaced.

Assuming every “Can I …?” is an ability question

• Potentially misleading: 여기 앉을 수 있어요?
• Clear permission question: 여기 앉아도 돼요?
• Why: 앉을 수 있어요? literally asks whether sitting here is possible, though context may make it a permission request. -아/어도 돼요? asks directly whether an action is allowed.

Usage Notes

-(으)ㄹ 수 없다 and 못

Both can translate as “cannot,” but they package the message differently.

• 오늘 갈 수 없어요. — I cannot go today; going is not possible under the circumstances.
• 오늘 못 가요. — I cannot make it today.

못 + verb is very common and compact in conversation. -(으)ㄹ 수 없다 often sounds more explicit or explanatory and is especially useful when discussing whether something is possible. The distinction is not absolute: in many everyday situations either form works, with the surrounding context carrying the nuance.

Be careful with spacing and word type in 하다 compounds. Many noun + 하다 verbs place 못 before 하다: 운전을 못 해요 (“I cannot drive”), while 운전할 수 없어요 uses the full ability construction.

Subjects are usually inferred

English requires a subject in “I can go” or “Can you come?” Korean often omits it. Add 저는, 제가, or 민수 씨는 only when the person is unclear or contrast matters:

• 저는 갈 수 있어요. — As for me, I can go.
• 누가 갈 수 있어요? — Who can go?
• 제가 갈 수 있어요. — I can go / I am the one who can go.

Questions can function as requests

창문을 열 수 있어요? may be understood as “Can you open the window?” and therefore as an indirect request. A more direct polite request is 창문을 열어 주세요 (“Please open the window”). Tone and situation determine whether the ability question feels natural, indirect, or overly literal.

Formal public language

Instructions, websites, and service notices often use -(으)ㄹ 수 있습니다/없습니다:

• 온라인으로 예약할 수 있습니다. — Reservations can be made online.
• 외부 음식을 반입할 수 없습니다. — Outside food cannot be brought in.

This formal ending changes the register, not the basic grammar.

Beyond the Basics / Advanced Use

You do not need to master the following details at A1, but they explain forms you will encounter later.

Marking contrast with 는

The topic marker 는 can attach to 수 as 수는 있다 or 수는 없다. This often means “it is possible, but…” and signals a limitation or contrast:

• 갈 수는 있어요. 하지만 늦을 거예요. — I can go, but I will be late.
• 읽을 수는 있지만 이해할 수는 없어요. — I can read it, but I cannot understand it.

The plain 갈 수 있어요 simply states ability. 갈 수는 있어요 often invites the listener to expect a qualification.

Possibility with completed events

A past-marked verb can occur before 수 있다 when the speaker is guessing about whether an event happened:

• 벌써 도착했을 수 있어요. — They may have arrived already.

This is different from 도착할 수 있었어요, which means “was able to arrive” or “could have arrived,” depending on context. The contrast is useful later:

Form	Main interpretation
도착할 수 있었어요	was able to arrive / could have arrived
도착했을 수 있어요	may have arrived

Nouns and descriptive verbs

The possibility meaning is not limited to action verbs. Descriptive verbs can describe a possible state:

• 겨울에는 아주 추울 수 있어요. — It can be very cold in winter.
• 그 일이 어려울 수 있어요. — That task may be difficult.

With a noun plus the copula 이다 (“to be”), the form is 일 수 있다:

• 오해일 수 있어요. — It may be a misunderstanding.

These examples are best understood as “may be” or “it is possible that,” not as personal ability.

Lexical alternatives

Korean also has verbs that express learned skills directly. 한국어를 할 수 있어요 means “I can speak/use Korean,” while 한국어를 해요 usually means “I speak/do Korean” in context. For specific skills, verbs such as 운전하다 (“drive”) and 수영하다 (“swim”) fit the same construction naturally: 운전할 수 있어요, 수영할 수 있어요.

Practice Tips

1. Sort new verbs by stem ending. Make three short lists: vowel stems such as 가다 → 갈 수 있어요, consonant stems such as 먹다 → 먹을 수 있어요, and ㄹ stems such as 만들다 → 만들 수 있어요. This makes the choice of -ㄹ/-을 automatic.
2. Practice useful question-and-answer pairs. Ask 오늘 만날 수 있어요?, 이걸 먹을 수 있어요?, or 카드로 낼 수 있어요? Then answer both positively and negatively. Change only 있어요/없어요 at first.
3. Listen for the intended meaning. When you hear -(으)ㄹ 수 있어요, decide whether it means ability, practical possibility, or uncertain possibility. Weather forecasts and service notices are especially good sources for the non-ability uses.

Related Concepts

• Prerequisite: Polite Ending -아/어요 — explains why 있다 and 없다 become 있어요 and 없어요 in everyday polite speech.