안 vs 못: Won't or Can't?

One says you chose not to. The other says something stopped you.

Both 안 and 못 sit in front of a verb and make it negative, so beginners often treat them as interchangeable. They are not, and the difference is one English speakers care about too.

술을 안 마셔요 means 'I don't drink' — a choice you have made. 술을 못 마셔요 means 'I can't drink' — an allergy, medication, a low tolerance, something outside your control. Using the wrong one can make you sound either rude or strangely helpless.

Quick Summary

안 = you choose not to. 못 = you would, but you are unable to.

Particle	Core Meaning	Used With	Example
안 (an)	Simple negation / choice	Verbs and adjectives	안 갔어요 I didn't go (I chose not to)
못 (mot)	Inability / prevented	Verbs only, never adjectives	못 갔어요 I couldn't go (something stopped me)

안

When to Use 안

1. A Decision You Made

안 is plain negation. It states that the action simply does not happen, usually because you decided so. It is the default negative in Korean.

저는 고기를 안 먹어요.

I don't eat meat.

2. With Adjectives

Only 안 can negate an adjective. Since 못 is about ability, and a quality has no ability, 못 예뻐요 is impossible.

오늘은 안 추워요.

It isn't cold today.

3. The Long Form: 지 않다

지 않다 is the formal written equivalent of 안, with exactly the same meaning. 안 먹어요 and 먹지 않아요 are interchangeable in meaning; the second is simply more formal.

그는 담배를 피우지 않습니다.

He does not smoke.

못

When to Use 못

Use 못 when you want to do something but cannot. The obstacle can be a skill you lack, a physical limit, no time, no money, or a rule. Because it is entirely about ability, 못 never attaches to adjectives. Its formal long form is Stem + 지 못하다.

배가 아파서 밥을 못 먹었어요.

I couldn't eat because my stomach hurt.

저는 수영을 못 해요.

I can't swim.

약속을 지키지 못했습니다.

I was unable to keep my promise.

Core Concept

안

Choice

"You decided not to"

못

Inability

"Something is in the way"

Common Mistakes

저는 안 예뻐요 / 저는 못 예뻐요

저는 안 예뻐요 (O)

"예쁘다 is an adjective. Adjectives describe a quality, not an ability, so they can only take 안."

못 공부해요 (X)

공부 못 해요 (O)

"With 하다 verbs, 못 splits the word and goes directly before 해요. The same applies to 안: 공부 안 해요."

시험에 떨어져서 안 갔어요

시험에 떨어져서 못 갔어요 (O)

"Failing the exam is an obstacle, not a preference. When an outside cause blocks you, use 못."

저는 술을 못 마셔요 (when you simply prefer not to)

저는 술을 안 마셔요 (O)

"Saying 못 implies you physically cannot. If you are just declining, 안 is the honest choice — though Koreans do sometimes use 못 as a polite way to refuse without explaining."

못 알아요 (X)

몰라요 (O)

"A few verbs have their own negative forms and reject 못 entirely: 알다 becomes 모르다, and 있다 becomes 없다."

How to Choose in 5 Seconds

Follow these 5-second rules.

Is the word an adjective?

Use안

Did you decide not to do it?

Use안

Do you lack the skill or ability?

Use못

Did something outside you get in the way?

Use못

Frequently Asked Questions

How is 못 pronounced?

The final consonant becomes [ㄷ], and it then assimilates to the next word. 못 해요 sounds like [모태요], 못 먹어요 like [몬머거요], and 못 가요 like [몯까요]. Koreans rarely pronounce it as a clean, separate 못.

What is the difference between 못 하다 and 못하다?

Spaced, 못 하다 means 'cannot do it'. Written together, 못하다 means 'to be bad at it'. 노래를 못 해요 = I can't sing right now. 노래를 못해요 = I sing badly.

Can 안 and 못 both appear with 지 forms?

Yes. 안 pairs with 지 않다 and 못 pairs with 지 못하다. Both long forms are more formal and are what you will see in writing and news.

Is using 못 ever considered impolite?

The opposite — it is often the polite option. Turning down an invitation with 못 가요 ('I can't go') sounds softer than 안 가요 ('I'm not going'), because it implies circumstances rather than disinterest.