Korean Hada Conjugation: Why 하다 Becomes 해요

What you'll learn

• Conjugate 하다 into six everyday forms: 해요, 했어요, 할 거예요, 합니다, 하세요 and 해.
• Apply the same forms to five 하다 words: 공부하다, 좋아하다, 운동하다, 깨끗하다 and 조용하다.
• Explain the 여 rule in one sentence and say why it makes 하다 "irregular".
• Tell 좋아해요 ("I like it") from 좋아요 ("it is good").

Prerequisites: you know how a verb splits into stem + ending and how vowel harmony picks 아요 or 어요, as taught in vowel harmony in conjugation. Time: about 20 minutes.

The first section answers the question most learners arrive with.

What Is the Polite Present of 하다?

The polite present of 하다 is 해요 (haeyo). It means "do", "does" or "am/are doing", depending on context, and it is the form you will use most with strangers, shop staff and colleagues. 해요 is the 해요체 (haeyo-che) form: the polite, everyday speech level of Korean.

Three sentences show 해요 at work, each with the stem 하 already replaced by 해:

Notice that 해요 never changes for the person. 저는 해요 ("I do"), 친구가 해요 ("my friend does") and 우리가 해요 ("we do") all use the same ending. The next section explains where the 해 comes from.

The 여 Rule: 하 + 여 Becomes 해

The 여 rule says that when an ending starting with 아 or 어 follows the stem 하, the vowel becomes 여, and 하 + 여 then shrinks to the single syllable 해. Most stems choose 아 or 어 by vowel harmony. The stem 하 has the bright vowel ㅏ, so you would expect 하 + 아요 = 하아요 or 하요. Neither exists. Korean uses 하여요, and speakers contract that to 해요.

The steps, built from the simplest case:

1. Remove 다. 하다 → stem 하.
2. Add the 여 ending, not 아 or 어. 하 + 여요 → 하여요.
3. Contract the two syllables. 하여 → 해, so 하여요 → 해요.
4. For the past, add 었 → 였 the same way. 하 + 였어요 → 하였어요 → 했어요.

The rule fires only before endings that begin with 아/어. Endings that begin with a consonant or with 으 attach to 하 without change: 하고 ("do and"), 하면 ("if you do"), 하는 ("that does"), 한 ("that did"), 할 ("that will do"), 합니다 (formal). A learner who remembers "only 아/어 endings change 하" can predict every form on this page.

Why Is 하다 Called a 여 Irregular?

하다 is called a 여 irregular (여 불규칙) because its ending does not follow vowel harmony. Korean's spelling rules, the Hangul Orthography (한글 맞춤법) published by the National Institute of Korean Language (국립국어원), list "하다" among the irregular conjugations in Article 18, and the irregular part is exactly this switch from 아 to 여.

Some textbooks avoid the word "irregular" and teach 하다 as its own regular class, because the rule never varies: thousands of 하다 words follow it without exception. Both descriptions are correct. The label matters less than the result: 하 + 아/어 ending → 해.

Is 해요 the Same as 하여요?

해요 and 하여요 are the same form, one contracted and one full. The Hangul Orthography allows the contracted spelling 해 for 하여, and in speech the contraction is the only one people use. You will never hear 하여요 in conversation; written it looks archaic or odd. The full 하여 survives in formal writing, which a later section covers.

The next section puts all the main forms of 하다 in one table.

Forms of 하다 in Six Slots

The six forms below cover most beginner sentences: present, past and future at the polite level, plus formal, honorific and casual. Each form either contains 해 (an 아/어 ending was added) or keeps 하 (a consonant ending was added).

Two everyday greetings hide in this table. 안녕하세요 is the honorific form of 안녕하다 ("to be at peace"), and 감사합니다 is the formal form of 감사하다 ("to be thankful"). Learners say both on day one without knowing they are 하다 conjugations.

The formal past follows the same logic: 했 + 습니다 = 했습니다 [해씀니다]. The casual past is 했어 [해써]. Both are covered in formal conjugation, which explains when the formal 합니다 style is expected.

Worked Example: 공부하다 Step by Step

To conjugate 공부하다 ("to study"), treat 공부 ("study", a noun) as a fixed front part and conjugate only the 하다 at the end. The steps are the same four as before.

1. Find the 하다 part. 공부하다 = 공부 + 하다.
2. Choose the slot. Polite present.
3. Apply the 여 rule to 하. 하 + 여요 → 해요.
4. Put the front part back. 공부 + 해요 = 공부해요.

The sentence 저는 한국어를 공부해요 means "I study Korean." For the past, step 3 gives 했어요, so the result is 공부했어요 [공부해써요]. For the formal level it gives 합니다, so 공부합니다 [공부함니다]. You'll know it worked when the front part stays untouched and only the last syllable changes. The next section tests whether the rule holds for every 하다 word.

Do All 하다 Verbs and Adjectives Follow the Same Rule?

Yes, all 하다 verbs and all 하다 adjectives follow the same rule, with no exceptions. The front part can be a Chinese-origin noun (공부, 운동), a native root (좋아-) or a descriptive root (깨끗-, 조용-), and the 하다 at the end still becomes 해요, 했어요 and 합니다.

The pronunciation of 깨끗해요 shows a sound change. The batchim ㅅ in 깨끗 is pronounced [ㄷ], and [ㄷ] + ㅎ merges into the aspirated [ㅌ]. That is why 깨끗해요 sounds like [깨끄태요]. The Standard Pronunciation Rules (표준 발음법) of the National Institute of Korean Language describe this merger as aspiration (거센소리되기).

Where Verbs and Adjectives Part Ways

The 여 rule is identical, but a few other forms differ, because 하다 verbs and 하다 adjectives belong to different word classes. Three differences matter early:

• Modifier before a noun. Verbs take 하는: 공부하는 학생 ("a student who studies"). Adjectives take 한: 깨끗한 방 ("a clean room").
• Requests. 공부하세요 can mean "please study". 깨끗하세요 is not a request; it can only describe a respected person ("you are clean").
• Negation with 안. For noun + 하다 verbs, 안 goes before 하다: 공부 안 해요 ("I don't study"). For adjectives, 안 goes in front of the whole word: 안 깨끗해요 ("it isn't clean").

These differences are part of a bigger split between verbs and adjectives, which Korean negation and the 하다 vocabulary pages explore further. The next section deals with the pair that confuses learners most.

좋아하다 Versus 좋다

좋아하다 and 좋다 look related, and they are, but they are different words with different stems. 좋다 is an adjective meaning "to be good" or "to be liked"; its stem 좋 takes vowel harmony and gives 좋아요 [조아요]. 좋아하다 is a verb meaning "to like"; its stem 좋아하 ends in 하, so it gives 좋아해요.

Both sentences can translate as "I like coffee", but the grammar is different. With 좋다, coffee is the subject that "is good". With 좋아하다, you are the subject and coffee is the object you like. Learners who mix them produce errors such as 커피를 좋아요. The same adjective-to-verb pattern appears in 싫다 / 싫어하다 ("to be disliked" / "to dislike"). The page on Korean feeling verbs lists the full set.

The next question is what 하다 actually means inside all these words.

When Is 하다 a Real Verb and When Is It a Suffix?

하다 is a real verb meaning "to do" when it stands alone or takes an object, as in 숙제를 해요 ("I do homework"). Inside a noun + 하다 verb such as 공부하다, it is a light verb that turns the noun into an action. Inside an adjective such as 조용하다, it is only a suffix and means nothing on its own.

A light verb (경동사) is a verb with little meaning of its own that carries the grammar for a noun. English has a similar pattern in "take a walk" or "do the dishes", where the noun holds the meaning. A suffix (접미사) is a word part that cannot stand alone. The conjugation is identical in all three cases, which is why one rule covers them. How these words are built is explained in what 하다 verbs are.

공부를 해요: Splitting the Noun

Many noun + 하다 verbs can be split by putting the object particle 을/를 on the noun. 공부해요 and 공부를 해요 both mean "I study", and the meaning stays the same. The split version adds a light emphasis on the activity, and it is common in speech.

The split works only when the front part is a noun. Adjectives such as 깨끗하다 cannot split: 깨끗을 해요 is wrong, because 깨끗 is not a noun. Verbs such as 좋아하다 cannot split either: 좋아를 해요 is wrong. For a long list of words that can split, see 하다 verbs. The last form to know appears mainly on paper.

Formal Writing Uses 하여

The full form 하여 still appears in formal writing: laws, official notices, academic papers and some news reports. 하여 means the same as 해, and 하였다 means the same as 했다. Spoken Korean always contracts them.

The connectives 대하여 ("about") and 위하여 ("for") are 하다 forms too, and both shorten in speech to 대해 and 위해. Read 하여 and 하였다 as 해 and 했다, and do not use them in conversation, where they sound stiff. The form 하여요 is never used in speech or modern writing. In written Korean both 하였다 and 했다 are correct; 했다 is the more common choice in everyday texts.

The next section collects the mistakes that come from all of this.

Korean Hada Conjugation Mistakes

Korean hada conjugation mistakes fall into four patterns. Each comes from applying a general rule where 하다 has its own.

Learners often assume 하다 follows vowel harmony. Actually 하 + 아요 would give 하아요 or 하요, and neither exists, because 하다 takes 여. Wrong: 공부하요. Right: 공부해요.

Learners often add 어요 after 해. Actually 해 already contains the ending's vowel. Wrong: 해어요, 했어어요. Right: 해요, 했어요. Fix: write 해 + 요 and nothing in between.

Learners often conjugate 좋다 as if it were 좋아하다. Actually 좋다 has no 하 in its stem. Wrong: 커피가 좋해요. Right: 커피가 좋아요, or 저는 커피를 좋아해요.

Learners often put 안 in the wrong place. Actually 안 goes before 하다 in noun + 하다 verbs and before the whole word everywhere else. Wrong: 안 공부해요 (heard in speech, but not the standard pattern). Right: 공부 안 해요. For 좋아하다, which has no noun part, the form is 안 좋아해요.

An honest limit: native speakers do say 안 공부해요 in casual speech, and textbooks disagree on how strictly to mark it. This page teaches 공부 안 해요 because it is the pattern grammar references describe for noun + 하다 verbs, and it is never wrong. Practice comes next.

Practice

Try each item before you read the answer key below.

1. Give the polite present of 하다.
2. Give the polite past of 운동하다.
3. Give the formal present of 공부하다.
4. Give the polite present of the adjective 피곤하다 ("to be tired").
5. Fix the error: 저는 음악을 좋아요.
6. Fix the error: 어제 숙제를 해었어요.
7. Make "I don't exercise" with 운동하다 and 안.
8. Is 하다 in 조용하다 a verb meaning "do", a light verb or a suffix?

Answer key

1. 해요.
2. 운동했어요 [운동해써요].
3. 공부합니다 [공부함니다].
4. 피곤해요. Adjectives follow the same 여 rule.
5. 저는 음악을 좋아해요. With 을/를, the verb must be 좋아하다. The alternative 음악이 좋아요 is also correct.
6. 어제 숙제를 했어요. 하 + 였 contracts to 했; no extra 어.
7. 운동 안 해요.
8. A suffix. 조용하다 describes a state; nothing is "done".

If you got items 1 to 4 right, you have the rule. If you missed item 5 or 6, reread the sections on 좋아하다 and on mistakes. The next section shows where to go from here.

What Should You Learn after 하다 to 해요?

After the 여 rule, learn the next contraction in the polite present: ㅐ and ㅔ stems. It explains why 보내다 gives 보내요 and 세다 gives 세요, because stems ending in ㅐ or ㅔ usually drop the 어 of the ending. The parent page, polite present conjugation, lists all seven contraction rules in order.

For vocabulary, the 하다 verbs section collects the most useful noun + 하다 words, and what 하다 verbs are explains how they are built.

What this page does not cover. It does not cover the causative and passive partners of 하다 words (such as 공부시키다), the honorific past 하셨어요, or 되다 verbs; 되다 has its own spelling trap, explained in the page on 돼요 and 되요. Korean hada conjugation is the base for all of them: master 해요 and 했어요 first. About this page. Last updated 2026-10-09. The Korean text, spoken forms and audio on this page were machine-generated and reviewed and signed off by Min-ji Park on 15 October 2026. Forms were cross-checked with the site's rule-based conjugation engine. Romanization follows the Revised Romanization of Korean and is shown only as a learning aid.

Frequently Asked Questions

What is the past tense of 하다? The polite past of 하다 is 했어요, pronounced [해써요]. It comes from 하 + 였어요, which contracts to 했어요. The formal past is 했습니다 and the casual past is 했어. Every 하다 word copies it, so 공부하다 becomes 공부했어요 and 깨끗하다 becomes 깨끗했어요 without any other change.

Do 하다 adjectives conjugate the same way as 하다 verbs? Yes. 하다 adjectives such as 깨끗하다, 조용하다 and 피곤하다 take exactly the same endings as 하다 verbs, so they give 깨끗해요, 조용했어요 and 피곤합니다. The differences lie elsewhere. Adjectives use 한 before a noun (깨끗한 방), cannot form requests, and put 안 before the whole word.

What is the difference between 좋아해요 and 좋아요? 좋아해요 comes from the verb 좋아하다, "to like", and takes an object with 을/를, as in 커피를 좋아해요. 좋아요 comes from the adjective 좋다, "to be good", and takes a subject with 이/가, as in 커피가 좋아요. Both can translate as "I like coffee", but the grammar differs.

How do I make a 하다 verb negative? For a noun + 하다 verb, put 안 between the noun and 하다, as in 공부 안 해요, "I don't study." For 하다 adjectives and for verbs without a noun part, put 안 in front of the whole word, as in 안 깨끗해요 and 안 좋아해요. The longer pattern 공부하지 않아요 works for every word.

What is the future tense of 하다? The everyday future of 하다 is 할 거예요, pronounced [할꺼예요]. It joins the stem 하 to the ending -ㄹ 거예요, so the 여 rule does not apply. 공부하다 gives 공부할 거예요, "I will study." The form 하겠어요 also exists and adds a sense of intention or polite willingness.

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