Korean Verb Conjugation Made Clear: Stems and Endings, the -아요/-어요 Rule, Past and Future Tenses, Honorifics and Irregular Verbs

One of the first things learners notice about Korean is that most of the important information in a sentence is gathered at the very end, in the verb. Tense, politeness, negation, intention and even the relationship between the speaker and the listener are all expressed through endings attached to the verb. A Korean sentence can leave out the subject entirely and still be perfectly clear, but it can almost never leave out the verb ending. Understanding verb conjugation is therefore like building the skeleton of Korean grammar: once it is in place, everything else has something to attach to.

At first there seem to be a great many rules, and the changing shapes of verbs can feel overwhelming. The good news is that Korean conjugation is remarkably regular compared with many European languages. There are no different endings for "I," "you" and "they," no grammatical gender and very few true exceptions. Once you understand a handful of core principles, you will be able to conjugate the vast majority of verbs on your own.

In this guide we work through Korean verb conjugation step by step: the concept of stems and endings, present, past and future tenses, formal and casual speech, negation, honorific expressions and the irregular verbs that most often confuse learners. Every section includes examples so you can see the rules in action.

Dictionary form, stem and ending

When you look up a Korean verb in a dictionary, it always ends in -다. Forms such as 가다 (to go), 먹다 (to eat) and 하다 (to do) are called the dictionary form or basic form. They are rarely used as they are in everyday conversation, but they are the starting point for every conjugation.

Remove the -다 and what remains is the stem. The stem of 가다 is 가-, the stem of 먹다 is 먹-, and the stem of 공부하다 (to study) is 공부하-. Conjugating a verb simply means attaching different endings to this stem. Learning to find the stem quickly is the very first skill to practise, because every rule in this guide depends on it.

Two features of the stem matter most. The first is whether it ends in a vowel or a consonant. 가- ends in a vowel, while 먹- ends in the consonant ㄱ, which Koreans call a batchim, a final consonant. The second is what the last vowel of the stem is. In 가-, it is ㅏ; in 먹-, it is ㅓ; in 보- (from 보다, to see), it is ㅗ. Keep these two questions in mind, as they decide which endings you use.

In Korean, adjectives also conjugate in the same way as verbs. Words such as 예쁘다 (to be pretty), 크다 (to be big) and 좋다 (to be good) take endings to become 예뻐요, 커요 and 좋아요, and they function as predicates on their own without any need for a word like "is." For this reason, linguists often call Korean adjectives "descriptive verbs," and almost all of the rules in this guide apply to them too.

The key to the present tense: the -아요/-어요 rule

The polite present tense ending used most often in everyday conversation, known as the haeyo style, is decided by the last vowel of the stem. This single rule is the most important one in Korean conjugation, because the past tense and many other forms are built on it.

• If the last vowel is ㅏ or ㅗ, add -아요: 살다 (to live) → 살아요, 좋다 (to be good) → 좋아요, 받다 (to receive) → 받아요
• If the last vowel is anything else, add -어요: 먹다 (to eat) → 먹어요, 읽다 (to read) → 읽어요, 있다 (to have, to exist) → 있어요
• If the verb ends in 하다, it becomes 해요: 하다 (to do) → 해요, 공부하다 (to study) → 공부해요, 좋아하다 (to like) → 좋아해요

Why does the vowel matter? Korean has a tradition of vowel harmony, in which "bright" vowels such as ㅏ and ㅗ tend to pair with each other and "dark" vowels pair with other dark vowels. You do not need to memorise the theory, but it explains why the ending changes and why the rule feels natural to native speakers.

The 하다 group deserves special attention because it is enormous. Many Korean verbs are formed by adding 하다 to a noun: 운동 (exercise) becomes 운동하다 (to exercise), 일 (work) becomes 일하다 (to work), and 전화 (telephone) becomes 전화하다 (to make a call). All of these simply become -해요, which makes a huge number of verbs easy to conjugate from the start.

Vowel contractions

When a stem ends in a vowel with no final consonant, the vowel of the stem and the vowel of the ending usually merge into a shorter form. This is what makes some conjugations look unfamiliar at first.

• Identical vowels merge: 가다 → 가요 (가 + 아요), 서다 (to stand) → 서요 (서 + 어요)
• ㅗ + ㅏ becomes ㅘ: 보다 → 봐요, 오다 (to come) → 와요
• ㅜ + ㅓ becomes ㅝ: 주다 (to give) → 줘요, 배우다 (to learn) → 배워요
• ㅣ + ㅓ becomes ㅕ: 마시다 (to drink) → 마셔요, 기다리다 (to wait) → 기다려요
• ㅚ + ㅓ becomes ㅙ: 되다 (to become) → 돼요

These contractions can seem strange at first, but they follow a clear logic: two vowels side by side are pronounced as one smooth sound. Practising with frequently used verbs is the quickest way to make them feel natural.

The past tense: -았어요/-었어요/했어요

The past tense follows exactly the same vowel rule as the present. Instead of attaching -아요 or -어요, you attach -았어요 or -었어요, and 하다 becomes 했어요. The contractions also work the same way.

• 가다 → 갔어요 (went)
• 보다 → 봤어요 (saw)
• 먹다 → 먹었어요 (ate)
• 마시다 → 마셨어요 (drank)
• 하다 → 했어요 (did)

A useful trick is to start from the present tense form. Take 봐요, remove 요 to get 봐, add ㅆ to get 봤, then add 어요: 봤어요. If you can form the present tense correctly, the past tense follows almost automatically. This is one reason why mastering the -아요/-어요 rule early pays off so well.

Future and intention: -(으)ㄹ 거예요

To talk about future plans or make a guess about something, use -(으)ㄹ 거예요. If the stem ends in a vowel, attach -ㄹ 거예요; if it ends in a consonant, attach -을 거예요.

• 가다 → 갈 거예요 (will go)
• 먹다 → 먹을 거예요 (will eat)
• 하다 → 할 거예요 (will do)

This form can express either a plan or a prediction depending on context. "내일 영화 볼 거예요" means "I'm going to watch a film tomorrow," describing a plan, while "비가 올 거예요" means "It will probably rain," expressing a guess. Korean also has a more formal future ending, -겠-, which you will hear in announcements and expressions such as 잘 먹겠습니다 (said before eating), but -(으)ㄹ 거예요 is the most useful form to learn first.

Conjugation table at a glance

Dictionary form	Present (haeyo)	Past	Future	Formal
가다 (to go)	가요	갔어요	갈 거예요	갑니다
먹다 (to eat)	먹어요	먹었어요	먹을 거예요	먹습니다
하다 (to do)	해요	했어요	할 거예요	합니다
보다 (to see)	봐요	봤어요	볼 거예요	봅니다
마시다 (to drink)	마셔요	마셨어요	마실 거예요	마십니다

Try covering the columns on the right and producing each form yourself from the dictionary form. Repeating this exercise with new verbs is one of the most effective ways to build fluency.

Formal speech and casual speech

Besides the haeyo style, Korean uses different speech levels depending on the situation and the relationship between speakers. Choosing the right level is as important as choosing the right tense.

In news broadcasts, presentations, military settings and formal occasions, people use the formal -(스)ㅂ니다 style. If the stem ends in a vowel, attach -ㅂ니다 (가다 → 갑니다); if it ends in a consonant, attach -습니다 (먹다 → 먹습니다). Questions in this style end in -(스)ㅂ니까: 갑니까?, 먹습니까? You will hear this style constantly in shops, on the subway and in customer service, so it is important to understand it even if you mostly speak in the haeyo style.

With close friends, younger siblings or people clearly younger than you, Koreans use casual speech called banmal. The easiest way to form it is to drop the 요 from the haeyo style: 가요 → 가, 먹어요 → 먹어, 했어요 → 했어. Banmal sounds warm and friendly between close people, but using it with strangers, older people or colleagues can come across as rude. When in doubt, the haeyo style is the safe choice, and you can switch to banmal when the other person suggests it.

Making negative sentences

There are two main ways to make a verb negative. The first, shorter way is to put 안 before the verb: 안 가요 (I don't go), 안 먹어요 (I don't eat). The second, slightly more formal way is to attach -지 않아요 to the stem: 가지 않아요, 먹지 않아요. Both mean the same thing, and the short form is more common in casual conversation.

With verbs formed from a noun plus 하다, 안 goes between the noun and 하다: 공부 안 해요 (I don't study), 운동 안 해요 (I don't exercise). Putting 안 at the front, as in 안 공부해요, sounds unnatural to native speakers.

When you want to say that you cannot do something, because of lack of ability or circumstances beyond your control, use 못 instead of 안. "수영 못 해요" means "I can't swim," while "수영 안 해요" means "I don't swim," suggesting it is a choice. The longer equivalent of 못 is -지 못해요: 가지 못해요 (I can't go). Distinguishing between 안 and 못 is a small detail that makes your Korean sound much more natural.

The progressive and honorific expressions

To describe an action happening right now, use -고 있어요 after the stem: 먹고 있어요 (I am eating), 공부하고 있어요 (I am studying), 비가 오고 있어요 (It is raining). In the past tense it becomes -고 있었어요: 자고 있었어요 (I was sleeping).

Korean also has a way of showing respect to the person who performs an action, usually someone older or of higher status. This is done by inserting -(으)시- into the verb. In the present tense, the most common form is -(으)세요: 가다 → 가세요, 읽다 → 읽으세요, 하다 → 하세요. "선생님이 오세요" means "The teacher is coming," with respect shown to the teacher. In the past tense the form becomes -(으)셨어요: 가셨어요, 하셨어요.

The same -(으)세요 form is also used for polite requests and suggestions. "여기 앉으세요" means "Please sit here," and "안녕히 가세요" (goodbye, literally "go in peace") uses the same pattern. Note that you never use the honorific -시- about yourself; it is always directed at someone else.

Irregular verbs you need to know

Some verbs change the shape of their stem when certain endings are attached. They can be confusing at first, but many of them are very common, so it is essential to learn them. The good news is that even the irregular verbs follow patterns, so they are not as random as they first appear.

• ㅂ irregular: A final ㅂ changes to 우 before a vowel. 덥다 (to be hot) → 더워요, 춥다 (to be cold) → 추워요, 쉽다 (to be easy) → 쉬워요. 돕다 (to help) becomes 도와요. Some verbs are regular, however, such as 입다 (to wear) → 입어요 and 좁다 (to be narrow) → 좁아요.
• ㄷ irregular: A final ㄷ changes to ㄹ before a vowel. 듣다 (to listen) → 들어요, 걷다 (to walk) → 걸어요, 묻다 (to ask) → 물어요. 받다 (to receive) and 닫다 (to close) are regular.
• 르 irregular: Stems ending in 르 gain an extra ㄹ. 모르다 (to not know) → 몰라요, 부르다 (to sing, to call) → 불러요, 빠르다 (to be fast) → 빨라요.
• ㅡ dropping: A final ㅡ in the stem disappears. 쓰다 (to write) → 써요, 크다 (to be big) → 커요, 바쁘다 (to be busy) → 바빠요, 예쁘다 (to be pretty) → 예뻐요.
• ㄹ dropping: A final ㄹ disappears before ㄴ, ㅂ or ㅅ. 살다 (to live) → 사세요, 삽니다; 알다 (to know) → 압니다, 아세요.
• ㅅ irregular: A final ㅅ disappears before a vowel. 낫다 (to get better) → 나아요, 짓다 (to build) → 지어요. 웃다 (to laugh) and 씻다 (to wash) are regular.

Rather than memorising lists of rules, focus on the irregular verbs you actually use. Words like 덥다, 춥다, 듣다, 모르다 and 바쁘다 come up in conversation every day, and once you have heard and said them many times, their irregular forms will feel completely natural.

Effective ways to practise

Conjugation becomes automatic not through memorising rules but through using common verbs again and again. Choose five verbs each day and say them aloud in the present, past, future and negative forms. Connect the practice to your real life: use the past tense when writing a short diary entry about your day, and use the future tense when describing your plans for tomorrow. Sentences about your own life are far easier to remember than abstract examples.

Listening practice also helps enormously. When you watch Korean dramas or listen to K-pop, try to catch verb endings and work backwards to the dictionary form. If you hear 몰라요, can you recognise that it comes from 모르다? If a character says 갔어, do you know it is the casual past tense of 가다? This kind of active listening trains your ear to notice the endings that carry so much meaning.

Finally, do not be afraid of making mistakes. Native speakers will almost always understand you even if you use the wrong ending, and every correction is a chance to learn. Many learners find that their conjugation improves fastest when they speak regularly with a tutor or language exchange partner who can gently point out errors.

Linking verbs: -고 and -아서/-어서

Real conversations rarely consist of single, isolated sentences. To connect actions smoothly, Korean uses connective endings attached to the verb stem, and two of them are especially useful for beginners.

The ending -고 simply links two actions or states, much like "and" in English. It attaches directly to the stem without any vowel changes: "밥을 먹고 커피를 마셔요" means "I eat a meal and drink coffee." Notice that only the final verb carries the tense and politeness; the first verb stays in its simple -고 form. You can also use -고 to list qualities: "싸고 맛있어요" means "It's cheap and delicious."

The ending -아서/-어서 is used for actions that are closely connected in sequence or for giving reasons. It follows exactly the same vowel rule as the present tense, and 하다 becomes 해서. "배가 고파서 밥을 먹었어요" means "I was hungry, so I ate," and "친구를 만나서 영화를 봤어요" means "I met my friend and (together) we watched a film." Because it reuses the -아요/-어요 rule, -아서/-어서 is easy to learn once the present tense is familiar, and it instantly makes your Korean sound more fluent.

Common beginner mistakes

Knowing which errors are most common can help you avoid them from the start.

• Mixing up the vowel rule: Learners often produce forms such as 먹아요 or 살어요. Before attaching an ending, always check the last vowel of the stem. If it is ㅏ or ㅗ, use -아-; otherwise use -어-.
• Using honorifics about yourself: Saying 저는 학생이세요 ("I am, honourably, a student") is a classic mistake. The honorific -시- is only ever used for other people, never for yourself.
• Confusing 안 and 못: Use 못 for things you are unable to do and 안 for things you choose not to do. Saying "I don't speak Korean" with 안 can sound as if you are refusing.
• Forgetting the contraction: Forms such as 보아요 or 마시어요 are understandable but sound old-fashioned or written. In speech, use 봐요 and 마셔요.
• Treating irregular verbs as regular: 듣어요 or 덥어요 are common slips. Make a short personal list of the irregular verbs you use most and review it regularly.

Every learner makes these mistakes at some point, so there is no need to worry. Simply being aware of them will help you notice and correct them much faster.

Frequently asked questions

Should I learn the haeyo style or the formal style first?

We recommend starting with the haeyo style, which is the most widely used in everyday conversation. It is polite yet friendly and works in most situations. Learn to recognise the formal -(스)ㅂ니다 style early too, since you will hear it often in public places.

How should I memorise irregular verbs?

It is better to memorise the common verbs themselves than the names of the rules. Repeat pairs aloud, such as 덥다–더워요, 듣다–들어요 and 모르다–몰라요, and they will gradually become familiar.

Do adjectives conjugate the same way?

Yes. Korean adjectives conjugate in almost exactly the same way as verbs. There are a few differences, however: for example, adjectives do not use the progressive -고 있어요 form, and they use different endings when they come before a noun.

Is it a problem if I mix up the speech levels?

Mixing levels is a common learner mistake, and people will usually be understanding. Still, try to stay consistent within a conversation. If you begin in the haeyo style with someone, keep using it unless they invite you to switch.

Final thoughts: hear the verb ending, and you hear Korean

Korean verb conjugation may look complicated at first, but mastering just one rule, the vowel-based -아요/-어요 pattern, unlocks the present, past and future all at once. Add honorifics, negation and irregular verbs one at a time, and the range of sentences you can express will grow quickly. Try conjugating a few everyday verbs with the rules you learned today. Once you begin to catch the endings of sentences, Korean will start to feel much closer and much more understandable.