Can/Able -(으)ㄹ 수 있다 in Korean

Overview

The pattern -(으)ㄹ 수 있다 expresses ability and possibility in Korean, equivalent to "can" or "be able to." This CEFR A1 structure is formed using the future modifier -(으)ㄹ plus 수 (way/method) plus 있다 (to exist). Literally, it means "a way to do X exists." The negative form replaces 있다 with 없다: -(으)ㄹ 수 없다 (cannot).

This is one of the most frequently used structures in Korean and appears in everyday situations like describing skills, asking permission, and discussing possibilities. It works with all action verbs and is straightforward to conjugate.

The pattern is also important because it introduces the concept of the future modifier -(으)ㄹ followed by a dependent noun (수), a grammatical pattern that appears in many other constructions at higher levels.

How It Works

Stem type	Pattern	Example
Vowel stem	-ㄹ 수 있다	갈 수 있다 (can go)
Consonant stem	-을 수 있다	먹을 수 있다 (can eat)
Negative	-(으)ㄹ 수 없다	갈 수 없다 (cannot go)

Conjugated in speech levels:

Level	Positive	Negative
Polite	-ㄹ 수 있어요	-ㄹ 수 없어요
Formal	-ㄹ 수 있습니다	-ㄹ 수 없습니다
Casual	-ㄹ 수 있어	-ㄹ 수 없어

Examples in Context

Korean	Romanization	English	Note
갈 수 있어요.	gal su i-sseo-yo	(I) can go.	ability
한국어를 할 수 있어요.	han-gu-geo-reul hal su i-sseo-yo	(I) can speak Korean.	skill
먹을 수 없어요.	meo-geul su eop-seo-yo	(I) can't eat.	inability
여기서 수영할 수 있어요?	yeo-gi-seo su-yeong-hal su i-sseo-yo	Can (I) swim here?	asking permission
내일 만날 수 있어요?	nae-il man-nal su i-sseo-yo	Can we meet tomorrow?	possibility
이해할 수 있어요.	i-hae-hal su i-sseo-yo	(I) can understand.	comprehension
운전할 수 있어요?	un-jeon-hal su i-sseo-yo	Can (you) drive?	ability question
도와줄 수 있어요?	do-wa-jul su i-sseo-yo	Can (you) help?	request
믿을 수 없어요!	mi-deul su eop-seo-yo	(I) can't believe it!	disbelief

Common Mistakes

Confusing 못 with -(으)ㄹ 수 없다

• Wrong: Thinking they are completely interchangeable
• Right: 못 먹어요 (can't eat, general inability) vs. 먹을 수 없어요 (cannot eat, emphasizing impossibility)
• Why: Both express inability, but -(으)ㄹ 수 없다 is more emphatic and formal. 못 is more conversational.

Wrong stem attachment

• Wrong: 가을 수 있어요
• Right: 갈 수 있어요
• Why: Vowel stems take -ㄹ (as batchim), not -을. This follows the same rule as the future tense.

Forgetting 수 in the pattern

• Wrong: 갈 있어요
• Right: 갈 수 있어요
• Why: 수 (method/way) is a required part of this grammar pattern and cannot be omitted.

Usage Notes

-(으)ㄹ 수 있다 is slightly more formal and deliberate than 못. In casual speech, Koreans often prefer 못 for inability. However, for questions about possibility and polite requests, -(으)ㄹ 수 있어요? is the standard form. This pattern is also used for general possibility: 내일 비가 올 수 있어요 (It might rain tomorrow).

Practice Tips

• List your skills using this pattern: 요리할 수 있어요, 수영할 수 있어요, 한국어를 읽을 수 있어요.
• Practice asking permission politely: ...할 수 있어요? This is useful for travel and daily situations.
• Convert 못 sentences to -(으)ㄹ 수 없다 sentences and notice the subtle difference in formality and emphasis.

Related Concepts

• Prerequisite: Polite Ending -아/어요 — 있다/없다 conjugates in the polite form