안 vs 못: Differences, Rules and Examples

What you'll learn

• Choose 안 or 못 for a given situation and explain the reason in one sentence.
• Place 안 or 못 correctly before a verb in a polite (해요체) sentence.
• Decide which word fits an adjective, and which word cannot.
• Fix the most common mistake: using 못 when you mean "I don't want to."
• Say the same idea in a past-tense sentence and in a written (long-form) sentence.

Before you start: you should know the polite ending -아요/-어요 and basic sentence order (subject, object, verb). If not, read the Korean SOV sentence pattern first. Audio plays only when you press a button.

What Is the Difference in 안 vs 못?

The difference in 안 vs 못 is the reason behind the negative. 안 says "I do not do it" and gives no reason, so it covers choice, habit and plain fact. 못 says "I am not able to do it" and points to a cause such as skill, health, time or weather. Most short negative sentences in everyday Korean use one of the two.

Two sentences built on the same verb show the contrast:

• 저는 술을 안 마셔요. (jeoneun sureul an masyeoyo.) = "I do not drink alcohol." This is a choice or a habit.
• 저는 술을 못 마셔요. (jeoneun sureul mot masyeoyo.) [몬 마셔요] = "I cannot drink alcohol." Something stops you, such as an allergy or a medicine.

The verb 마셔요 is the same in both. Only the small word before it changes the meaning. The next sections turn this into a rule you can apply in a few seconds.

The One-Line Rule

Use 안 when you will not or do not, and use 못 when you cannot. Ask yourself one question before you speak: "Is it my decision, or is something stopping me?" If it is your decision or simply a fact, say 안. If something stops you, say 못. If you cannot tell which one applies, 안 is the safer default, because it makes no claim about your ability.

Side-by-Side Comparison of 안 and 못

The table compares 안 and 못 on the points learners need most. Each row has one specific answer for each word.

The table shows that the two words share a position but differ in meaning and in what they can attach to. Next, one sentence is built step by step to show how the choice is made.

Worked Example: 안 vs 못 on One Sentence

안 vs 못 works by inserting one small word before the verb of an ordinary sentence. Follow the steps below with the sentence "I go to school."

1. Start with the positive sentence. 저는 학교에 가요. (jeoneun hakgyoe gayo.) = "I go to school." The verb is 가요.
2. Find the verb. In 저는 학교에 가요, the verb is 가요, the last word of the sentence. Everything before it stays unchanged.
3. Decide the reason. Ask whether you are choosing not to go, or something stops you. Suppose today is Sunday and there is no class: that is a plain fact, so choose 안. Suppose you are sick: something stops you, so choose 못.
4. Insert the word before the verb. Put it directly in front of 가요, with a space.
5. Read the result. The Sunday sentence is 저는 학교에 안 가요. (jeoneun hakgyoe an gayo.) = "I don't go to school (it's Sunday)." The sick-day sentence is 저는 학교에 못 가요. (jeoneun hakgyoe mot gayo.) [몯 까요] = "I can't go to school (I'm sick)."

You will know it worked when the verb ending did not change and the extra word sits right before the verb. The most common slip at this step is putting the negative word at the end of the sentence, as English "not" sometimes does. In Korean it always comes before the verb.

Here is the same method on a second verb, 먹다 (to eat). 저는 매운 음식을 안 먹어요 means "I don't eat spicy food" because you dislike it or avoid it. 저는 매운 음식을 못 먹어요 [몬 머거요] means "I can't eat spicy food" because it is too hot for you or you are allergic. The skill is the same, and only the reason differs. Real conversations raise a further question: which one should you pick when a friend invites you?

Which Should You Choose in Each Situation?

Choose 안 for habits, preferences and facts, and choose 못 for skill, health, time and weather. The table below sorts everyday situations. Each row names the situation, the right word and a model sentence.

When you decline an invitation, 못 usually sounds softer. 오늘은 못 가요 ("I can't go today") puts the blame on circumstances, while 오늘은 안 가요 ("I'm not going today") states your own decision and can sound blunt. Politeness also depends on tone, so adding 죄송해요 (I'm sorry) before either sentence helps. This is a tendency in everyday speech, not a grammar rule.

Choosing between the two is mostly about meaning, so the mistakes below almost always come from mixing up the meaning.

What Mistakes Do Learners Make with 안 vs 못?

Learners most often confuse the reason behind the negative. Four mistakes appear again and again, and each has a quick repair.

1. Using 못 for "I don't want to." Learners often assume that 못 is the polite way to say no. Actually, 못 claims that you are unable, so 저는 커피를 못 마셔요 tells the listener you cannot drink coffee. If you just dislike it, say 안 마셔요. A person who hears 못 may offer a solution, such as a different drink.
2. Using 안 for "I can't." 저는 수영을 안 해요 means "I don't swim," which sounds like a choice. For lack of skill, say 저는 수영을 못 해요.
3. Putting 못 before an adjective. 못 예뻐요 and 못 비싸요 are not standard. Adjectives describe states, not actions you try to do. Use 안 예뻐요 (not pretty) and 안 비싸요 (not expensive).
4. Stacking both words. 안 못 가요 is wrong. Pick the single word that matches your reason. To combine ideas, use two sentences: 비가 와서 못 가요 (I can't go because it rains).

Use this checklist when a negative sentence feels wrong: Is the word before the verb? Is the verb an action? Is the reason a choice or a block? Edge cases follow from the same checklist.

When Do 안 and 못 Work Differently?

안 and 못 work differently in four cases: circumstances, commands, tenses and the verb 하다. Each case below gives the rule and one example.

• Circumstance, not only ability. 못 does not need a skill problem. It also covers anything outside your control: 비 때문에 못 갔어요. (bi ttaemune mot gasseoyo.) = "I couldn't go because of the rain." Here you have the ability to walk, but the rain blocked you.
• Facts use 안. For a plain fact with no person choosing, use 안: 오늘은 비가 안 와요 ("It isn't raining today"). 못 would sound strange because rain does not "try" to fall.
• Commands and suggestions. Neither word can make "don't" in a request. 안 가세요 is a statement or a question, and 못 가세요 can only describe a respected person's inability ("he cannot go"), never a request. For "please don't go" use the pattern in the lesson on -지 마세요 don't.
• Past tense. Both words stay before the verb and the verb takes its past form: 안 갔어요 (didn't go) and 못 갔어요 (couldn't go).
• 하다 verbs. The word goes between the noun and 하다: 운동 안 해요, 운동 못 해요. This is explained in negating 하다 verbs 공부 안 해요.

An honest limit: this lesson covers the short forms used in everyday speech. Neither 안 nor 못 shows how strong the inability is, and Korean has more words, such as 도저히 (no way, in no case) and 전혀 (not at all), for stronger cases. Those words belong to later lessons. The long forms deserve a short look because tests and written Korean use them.

How Do the Long Forms -지 않다 and -지 못하다 Relate?

The long forms keep the same split: -지 않다 matches 안, and -지 못하다 matches 못. To build them, drop 다 from the dictionary form, add -지, and then add 않다 or 못하다. For 가다: 가지 않아요 (don't go) and 가지 못해요 (can't go). The long forms are more formal. See -지 못하다 cannot and -지 않다 negation for the full rules.

The long forms confirm that the choice-or-inability split is built into Korean grammar, so the practice below tests the split directly.

Practice and Answers

Try the four items before you read the answer key. Cover the answers with your hand.

1. Choose the form. You are a vegetarian by choice. Complete: 저는 고기를 ___ 먹어요. (안 / 못)
2. Fix the error. A friend is allergic to eggs and says 저는 계란을 안 먹어요 to explain that they cannot eat eggs. What would be more accurate?
3. Translate. "I can't go to the party because I have a test." Use 못 and 가요.
4. Write your own. Write one sentence with 안 and one sentence with 못, using any verbs you know. Say each reason in English.

Answer key

1. 안. It is a choice, so the sentence is 저는 고기를 안 먹어요.
2. 저는 계란을 못 먹어요. The allergy blocks the action, so 못 is the accurate word. (안 is not a grammar error, but it hides the real reason.)
3. 시험이 있어서 파티에 못 가요. (siheomi isseoseo patie mot gayo.) The reason clause 시험이 있어서 means "because I have a test." Any order that keeps 못 before 가요 is correct.
4. Answers vary. Check that each negative word sits right before its verb, the 안 sentence shows a choice or a fact, and the 못 sentence shows something blocking the action. An example: 일요일에는 일을 안 해요. (I don't work on Sundays.) and 저는 노래를 못 해요. (I can't sing.)

Check your understanding with one more rule of thumb: if the English sentence can use "can't" or "couldn't," use 못. If it uses "don't," "didn't" or "isn't," use 안.

Next Lessons after 안 vs 못

After 안 vs 못, study each word on its own, then the long forms. This lesson compares the two words but does not teach every use of either one. Detailed rules, such as adjectives with 안 and the meaning of the one-word 못하다 ("be bad at"), live on their own pages.

1. Start with 안 negation in Korean, which covers the 안 pattern in depth.
2. Continue with 못 can't in Korean, which covers 못 and the spacing difference between 못 하다 and 못하다.
3. Learn the written forms: -지 않다 negation and -지 못하다 cannot.
4. Return to Korean negation to see every lesson in the set, or compare other pairs on Korean grammar differences.

With these steps, the choice in 안 vs 못 becomes automatic: decide whether you will not or cannot, then place the word before the verb.

Frequently Asked Questions

Does 안 vs 못 change the verb ending?

No. The verb keeps its normal ending, and the negative word goes in front of it. 마셔요 becomes 안 마셔요 or 못 마셔요, with the same 요 ending. Only the long forms, -지 않아요 and -지 못해요, rebuild the verb as a stem plus -지 and a helper verb.

Can I use 못 when I do not want to do something?

No. 못 says that something stops you, such as skill, time, health or weather. If you simply do not want to, use 안. Saying 못 when you mean 안 sounds like an excuse, and a listener may ask what is wrong. Saying 안 when you mean 못 sounds like a refusal.

Which word is more polite for turning down an invitation?

못 usually sounds softer, because the cause is outside your control: 오늘은 못 가요 (I can't go today). 안 가요 states your own decision and can sound blunt. Politeness also depends on the verb ending and tone, so add a short reason or an apology to either one.

Are 안 and 못 used in writing as well as speech?

Both appear in speech and everyday writing such as messages and diaries. Formal writing, like reports and news, prefers the long forms 가지 않았다 and 가지 못했다. The long forms mean the same as 안 and 못, and they are common in exams and written Korean.

How do I say "I can't swim" in Korean?

Say 저는 수영을 못 해요. The word 못 goes between 수영 and 해요, because 수영하다 is a 하다 verb. Do not say 수영을 안 해요, which means "I don't swim" and does not tell the listener whether you are unable or just choose not to.

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