-기 Nominalizer: Meaning, Rules and Examples

What you'll learn

• Add 기 to any verb or adjective stem to make a noun.
• Use the noun with particles and with patterns such as 읽기 쉽다 and 만나기로 하다.
• Tell -기 apart from -는 것 and -(으)ㅁ at a basic level.
• Avoid errors such as 먹기 싶어요 and 들기 for "listening".

Prerequisites: the polite ending -아요/어요, and the idea of a verb stem (verb stems). Time: about 15 minutes.

Listen to the two model sentences for this lesson.

The next section defines the ending and shows it inside two sentences.

What Is the -기 Nominalizer?

The -기 nominalizer is the ending that makes a noun out of a verb or an adjective. A nominalizer is an ending that lets a whole verb behave like a noun, so it can take particles (small words such as 을/를 and 이/가 that mark a noun's job in the sentence). In English the same job is done by the "-ing" form: "Reading is fun." Korean uses 기 for this job, and 읽기 means "reading".

The noun made with 기 is mostly about an action as an activity. It has no tense by itself and no subject of its own. That makes it a good choice for hobbies, goals, rules, skills and plans. Textbooks use it for the four language skills: 듣기 (listening), 말하기 (speaking), 읽기 (reading) and 쓰기 (writing).

A First Example

In both sentences the 기 noun stands where any noun would stand and takes an ordinary particle. The next section shows how to build the form from any stem.

How Do You Form -기?

The -기 form is built by adding 기 directly to the stem, whatever the last sound of the stem is. The stem is the verb without the final 다. There is no choice between 기 and 이기, and no vowel harmony. The table gives one case for each stem type that learners ask about.

Three points explain the table.

Irregular stems do not change. In the polite ending the stem of 듣다 becomes 들- ([들어요]), 돕다 becomes 도와요, and the ㄹ of 살다 would drop in front of ㄴ. Those changes happen only when the next sound is a vowel or ㄴ. The syllable 기 starts with the consonant ㄱ, so the stem stays whole: 듣기, 돕기, 살기. The same rule is explained in ㄷ irregular, ㅂ irregular and ㄹ irregular.

Speech tenses the ㄱ. After a stem that ends in a stop sound (ㄱ, ㄷ or ㅂ), the ㄱ of 기 is said as the tense sound ㄲ, so 먹기 is [먹끼] and 듣기 is [듣끼]. The Standard Pronunciation Rules (표준발음법, Article 23) describe this. The ㄱ is also tense after a verb stem that ends in ㄴ or ㅁ (Article 24), so 신기, from 신다 (put on shoes), is [신끼]. After a vowel or ㄹ the ㄱ stays plain: 가기 and 살기 sound as spelled. Revised Romanization (RR, the official Latin spelling) does not show this tensing, so 먹기 is written meokgi.

Adjectives work too. 크다 gives 크기, which means "size", and 높다 gives 높기. Only a few adjective forms are common as ordinary nouns, but all of them can be used in the patterns in the next sections.

The next section builds a full sentence from a plain verb.

Worked Example: Building 제 취미는 영화 보기예요

To say "My hobby is watching movies", start from the verb and add 기 in five steps.

1. Pick the verb. The idea is "watch", so the dictionary form is 보다.
2. Take off 다. The stem is 보-.
3. Add 기. 보 + 기 gives 보기, a noun that means "watching".
4. Put the object first. 영화 보기 means "movie watching". The object noun comes right before the 기 noun, and the object particle is usually dropped in a set phrase like this.
5. Finish with 이다. 보기 ends in a vowel, so the ending is 예요: 제 취미는 영화 보기예요.

You'll know it worked when the 기 noun can be replaced by a plain noun without breaking the sentence. 제 취미는 음악이에요 ("My hobby is music") has the same shape. In the full sentence 제 취미는 means "my hobby is", so 보기 sits in the place of the noun that names the hobby.

The next section shows the places where the form is used most.

When Do You Use -기?

Use -기 for four jobs: to name an activity, to say how easy or hard an action is, to build fixed patterns, and to write short rules. Each job has its own habits.

1. Naming an activity. The noun can take any particle: 읽기가 어려워요 ("Reading is hard"), 읽기를 좋아해요 ("I like reading"), 읽기는 쉬워요 ("Reading is easy"). Titles and course names often omit the particle: 책 읽기, 한국어 말하기, 달리기 ("running").

2. Rating an action. A 기 noun comes before an adjective that says how an action feels. The two words are written with a space between them.

The spoken forms are [일끼 쉬워요], [걷끼 조은 날씨예요] and [하기 시러요]. The adjectives 쉽다 and 어렵다 are ㅂ-irregular, which is why they appear as 쉬워요 and 어려워요 here.

3. Fixed patterns. Some very common grammar points are the 기 noun plus a particle or a helper word.

• -기로 하다 means "decide to": 내일 만나기로 했어요. ("We decided to meet tomorrow.") The particle 로 marks the decision.
• -기 시작하다 means "begin to": 비가 오기 시작했어요. ("It began to rain.") Spoken: [비가 오기 시자캐써요].
• -기 바라다 means "hope that", often in formal greetings: 건강하시기를 바랍니다. ("I hope you stay healthy.")
• -기 전에, -기 때문에 and -기 위해(서) mean "before", "because" and "in order to". They have their own lessons: -기 전에 (before), -기 때문에 (because) and -기 위해(서) (in order to).

4. Short rules and lists. A line that ends in 기 reads like a heading or a rule. A classroom poster might say 수업 시간에 지각하지 않기 ("No being late for class"). The negative form uses -지 않기, and 않기 sounds like [안키].

Some 기 nouns have become ordinary dictionary words. In school mathematics 더하기 is addition, 빼기 is subtraction, 곱하기 is multiplication and 나누기 is division. The next section compares -기 with its two closest relatives.

How Is -기 Different from -는 것 and -(으)ㅁ?

The -기 noun names an activity, a plan or a wish, while -는 것 names a fact, a thing or something seen, and -(으)ㅁ gives a result or state in writing. The three can look alike in English because all of them can be translated with "-ing" or "the fact that".

A quick test helps. If the sentence describes how easy, hard, good or unpleasant an action is, or if it is a fixed pattern such as -기로 하다, use -기. If a verb of knowing or seeing sits at the end, as in 알다 ("know") or 보다 ("see"), use -는 것. For a full comparison with more verbs and a decision order, see -기 vs -는 것 vs -(으)ㅁ. The separate lessons are -는 것 nominalizer and -(으)ㅁ nominalizer.

Many predicates accept both. 말하기를 좋아해요 and 말하는 것을 좋아해요 both mean "I like speaking", and the difference is small. The next section covers the limits of -기.

What Can -기 Not Do?

The -기 noun cannot report a known fact, it cannot form a progressive action, and it does not name a real thing. These three limits cause most errors.

• No fact clauses. To say "I know that he is a student", use -는 것 or -(으)ㄴ 것: 그가 학생인 것을 알아요. A form such as 그가 학생이기를 알아요 is wrong.
• No progressive. "I am eating" is 먹고 있어요, never 먹기 있어요. The pattern -고 있다 shows an action in progress.
• No wish with 싶다. "I want to eat" is 먹고 싶어요 [먹꼬 시퍼요]. The word 싶다 needs -고, not -기.

What this lesson does not cover. It does not cover the full pattern lists of -기 위해서 and -기 전에, which have their own lessons, and it does not cover -기가 무섭게, -기 마련이다 or other less frequent patterns.

An honest limit. Native speakers often choose between -기 and -는 것 by habit, so no rule predicts every choice. Learn the common partners (쉽다, 어렵다, 좋다, 싫다, 바라다, 시작하다) as units, and use -는 것 when none of them fits.

The next section collects the errors that appear most often.

What Mistakes Do Learners Make with -기?

Learners make six predictable mistakes with -기. Each one has a reason and a fix.

Learners often assume -기 means "-ing" everywhere. Actually the progressive is -고 있다. Wrong: 지금 먹기 있어요. Right: 지금 먹고 있어요. Fix: ask whether the action is happening now; if it is, use -고 있다.

Learners often use 싶다 with -기. Actually 싶다 needs -고. Wrong: 먹기 싶어요. Right: 먹고 싶어요. Fix: remember that "want to" is -고 싶다.

Learners often change the stem of an irregular verb. Actually 기 starts with a consonant, so the stem stays. Wrong: 들기 for "listening", which is a different word and means "lifting". Right: 듣기. Fix: keep the dictionary stem before 기.

Learners often forget the space. Actually 쉽다 and 어렵다 are separate words. Wrong: 읽기쉬워요. Right: 읽기 쉬워요. Fix: write a space after the 기 noun.

Learners often use -기 for a real thing. Actually the noun means the activity, not the object. Wrong: 먹기가 맛있어요 for "the food is tasty". Right: 음식이 맛있어요. Fix: name the thing, or use 먹기 좋아요 for "it is nice to eat".

Learners often use -기 for a fact. Actually facts need -는 것. Wrong: 그가 학생이기를 알아요. Right: 그가 학생인 것을 알아요. Fix: after 알다 and 보다, switch to -는 것.

Practice turns these rules into habits, as the next section shows.

Practice and Answers

Complete the four tasks, then compare your answers with the key.

Task 1: choose the form. Write the -기 form of each verb.

1. 쓰다 (write)
2. 듣다 (listen)
3. 말하다 (speak)
4. 걷다 (walk)

Task 2: fix the error. Each sentence has one mistake. Rewrite it correctly.

1. 읽기쉬워요.
2. 먹기 싶어요.
3. 지금 먹기 있어요.

Task 3: translate. Write in Korean: "This book is easy to read." and "We decided to meet tomorrow."

Task 4: write your own. Write one sentence about a skill you like or dislike, using 좋아해요 or 싫어해요, for example 저는 한국어 말하기를 좋아해요.

Answer key

1. (1) 쓰기 (2) 듣기 (3) 말하기 (4) 걷기.
2. (1) 읽기 쉬워요. (2) 먹고 싶어요. (3) 지금 먹고 있어요.
3. 이 책은 읽기 쉬워요. 내일 만나기로 했어요.
4. Sample answers: 저는 한국어 쓰기를 좋아해요. 저는 아침에 일어나기를 싫어해요. Any 기 noun with a particle and a predicate is correct.

If task 1 was correct, you have the formation rule. If task 2 was hard, return to the section on what -기 cannot do. The next section points you to the lessons that follow.

Next Lessons after the -기 Nominalizer

After the -기 nominalizer, learn the written form in -(으)ㅁ nominalizer and the everyday form for facts in -는 것 nominalizer. Then read -기 vs -는 것 vs -(으)ㅁ to see all three together.

The wider set is listed on the parent page, Korean nominalization. For particles that follow a 기 noun, see object particle 을/를.

This lesson covers the form and its four main jobs. It does not cover the longer patterns built on -기. About this page. Last updated 2026-10-09. The Korean text and spoken forms on this page were generated with AI assistance. Romanization follows the Revised Romanization of Korean and is shown only as a learning aid.

Frequently Asked Questions

What does the -기 nominalizer mean? The -기 nominalizer is an ending that turns a verb or an adjective into a noun for an activity, a goal or a wish. 읽다 becomes 읽기 ("reading"), and 말하다 becomes 말하기 ("speaking"). The noun can take particles, as in 읽기를 좋아해요 ("I like reading"), and it has no tense of its own.

How do I form -기? Add 기 to the verb or adjective stem, which is the dictionary form without 다. 가다 gives 가기, 먹다 gives 먹기 and 말하다 gives 말하기. The stem never changes, even for irregular verbs: 듣다 gives 듣기, 돕다 gives 돕기, and 살다 gives 살기. The only change is in speech, where the ㄱ becomes tense after a stop or after a verb stem ending in ㄴ or ㅁ.

What is the most common mistake with -기? The most common mistake is using -기 where another ending is needed. Learners write 먹기 싶어요 for "I want to eat", but the correct form is 먹고 싶어요. The second mistake is 먹기 있어요 for "I am eating", which should be 먹고 있어요. A third is changing the stem of 듣다 to 들기, which means "lifting".

How is -기 different from -는 것 and -(으)ㅁ? The -기 noun names an activity, a plan or a wish, and it pairs with 쉽다, 어렵다, 좋다, 싫다 and 바라다. The -는 것 form names a fact or a thing and pairs with 알다 and 보다. The -(으)ㅁ form is used in written notes and formal text. Many verbs accept both -기 and -는 것.

Do I use -기 in speech, writing or both? Both. The -기 noun is natural in conversation, in textbooks and in written notices. 걷기 좋은 날씨예요 sounds normal in speech, and 지각하지 않기 works on a classroom poster. Only the sentence ending changes with politeness. The 기 noun itself stays the same in casual, polite and formal speech.

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