-기 vs -(으)ㄴ/는 것

Both -기 and -(으)ㄴ/는 것 turn verbs and adjectives into nouns, but they have different nuances and usage patterns. Understanding when to use each will make your Korean sound more natural.

Basic Difference

-기: Abstract and General

Focuses on the action/state itself:

• 수영하기 (swimming - the activity itself)
• 읽기 (reading - the act of reading)
• 공부하기 (studying - the activity)

Like English: "swimming", "reading" (gerund as pure noun)

-(으)ㄴ/는 것: Specific and Concrete

Focuses on particular instances or facts:

• 수영하는 것 (the act of swimming - specific instance)
• 읽는 것 (what/the thing I read)
• 공부하는 것 (what/the thing I study)

Like English: "what I read", "the thing I do"

Formality Level

-기: More Formal

Sounds more academic or formal:

• 한국어를 배우기가 어렵습니다 (Learning Korean is difficult - formal)
• 매일 운동하기를 권장합니다 (We recommend exercising daily - formal)

Common in: Written language, formal speech, academic contexts

-(으)ㄴ/는 것: More Conversational

Sounds more natural in everyday speech:

• 한국어를 배우는 것이 어려워요 (Learning Korean is difficult - natural)
• 매일 운동하는 것이 좋아요 (Exercising daily is good - conversational)

Common in: Casual conversation, daily interactions

When Each is Preferred

Must Use -기

With 전에 (Before)

Only -기 works:

• ✅ 먹기 전에 (before eating)
• ❌ 먹는 것 전에 (incorrect)

With 때문에 (Because)

Only -기 works:

• ✅ 바쁘기 때문에 (because [I'm] busy)
• ❌ 바쁜 것 때문에 (sounds awkward)

With -로 하다 (Decide to)

Only -기 works:

• ✅ 가기로 했어요 (decided to go)
• ❌ 가는 것으로 했어요 (incorrect in this meaning)

Evaluating Difficulty

-기 is more natural:

• ✅ 발음하기가 어려워요 (pronouncing is difficult)
• △ 발음하는 것이 어려워요 (grammatical but less common)

With -만 하다 (Only do)

Only -기 works:

• ✅ 자기만 해요 (only sleep)
• ❌ 자는 것만 해요 (incorrect)

Must Use -(으)ㄴ/는 것

With 같다 (Seems/Looks like)

Only 것 works:

• ✅ 비가 오는 것 같아요 (It seems like it's raining)
• ❌ 비가 오기 같아요 (incorrect)

For -(으)ㄹ 거예요 (Going to)

Only 것 works:

• ✅ 갈 거예요 (I'm going to go)
• ❌ 가기예요 (incorrect)

With Perception Verbs (보다, 듣다)

Only 것 works naturally:

• ✅ 그가 가는 것을 봤어요 (I saw him going)
• ❌ 그가 가기를 봤어요 (incorrect)

With Question Words for Specific Things

것 is more natural:

• ✅ 먹고 싶은 것이 뭐예요? (What do you want to eat?)
• △ 먹고 싶기가 뭐예요? (awkward)

When Including Subjects/Objects in the Clause

것 allows full clauses:

• ✅ 친구가 오는 것을 봤어요 (I saw my friend coming)
• △ 친구가 오기를 봤어요 (awkward/incorrect)

Can Use Both (with nuance difference)

Expressing Likes/Dislikes

-기: General preference:

• 수영하기를 좋아해요 (I like swimming - general activity)

것: Specific instances:

• 수영하는 것을 좋아해요 (I like swimming - more conversational)

Both acceptable, but 것 is more common in speech

As Subject of Sentence

-기: More formal:

• 한국어 배우기가 재미있어요 (Learning Korean is fun - formal)

것: More natural:

• 한국어 배우는 것이 재미있어요 (Learning Korean is fun - natural)

Both grammatical, choose based on formality

Detailed Comparison by Pattern

With Likes/Preferences

-기를 좋아하다

General liking:

• 음악 듣기를 좋아해요 (I like listening to music - in general)
• 책 읽기를 좋아해요 (I like reading books - in general)

Feels: Formal, emphasizes the activity itself

-는 것을 좋아하다

Specific preference:

• 음악 듣는 것을 좋아해요 (I like listening to music - more specific)
• 책 읽는 것을 좋아해요 (I like reading books - conversational)

Feels: Natural, conversational

Reality: In casual conversation, -(으)ㄴ/는 것 is more common

As Sentence Subject

-기가 Adjective

Formal evaluation:

• 발음하기가 어려워요 (Pronouncing is difficult)
• 이해하기가 쉬워요 (Understanding is easy)
• 외우기가 힘들어요 (Memorizing is hard)

Best for: Formal writing, academic contexts

-는 것이 Adjective

Natural evaluation:

• 발음하는 것이 어려워요 (Pronouncing is difficult)
• 이해하는 것이 쉬워요 (Understanding is easy)
• 외우는 것이 힘들어요 (Memorizing is hard)

Best for: Casual conversation, daily speech

With Time Expressions

-기 전에 (Before)

Only -기 works:

• 자기 전에 (before sleeping)
• 먹기 전에 (before eating)
• 시작하기 전에 (before starting)

-(으)ㄴ 후에 (After)

Can use both:

• 먹은 후에 (after eating)
• 먹고 나서 (after eating - different pattern)

Usage Frequency in Speech

More Common with -기

Fixed expressions:

• -기 전에 (before)
• -기 때문에 (because)
• -기로 하다 (decide to)
• -기 시작하다 (start to)
• -기만 하다 (only do)
• -기가 어렵다 (difficult to)

More Common with -(으)ㄴ/는 것

Everyday expressions:

• -는 것 같다 (seems like)
• -(으)ㄹ 거예요 (going to)
• -는 것을 보다 (see that...)
• -는 것을 좋아하다 (like doing - conversational)
• -는 것이 좋다 (it's good to)

Practical Examples

Example 1: Studying

With -기 (Formal)

• 한국어를 공부하기가 중요해요 (Studying Korean is important)
• 매일 복습하기를 권장합니다 (We recommend reviewing every day)

With 것 (Natural)

• 한국어를 공부하는 것이 중요해요 (Studying Korean is important)
• 매일 복습하는 것이 좋아요 (Reviewing every day is good)

Example 2: Opinions

With -기

• ✅ 일찍 일어나기가 힘들어요 (Waking up early is hard - formal)

With 것

• ✅ 일찍 일어나는 것이 힘들어요 (Waking up early is hard - natural)
• ✅ 일찍 일어나는 것 같아요 (It seems [they] wake up early)

Example 3: Fixed Patterns

Must use -기

• 자기 전에 (before sleeping)
• 먹기 때문에 (because [I] eat)
• 가기로 했어요 (decided to go)

Must use 것

• 비가 오는 것 같아요 (It seems like it's raining)
• 갈 거예요 (I'm going to go)
• 가는 것을 봤어요 (I saw [them] going)

Common Mistakes

❌ Wrong: 비가 오기 같아요

Cannot use -기 with 같다

✅ Correct: 비가 오는 것 같아요

Must use 것 with 같다

---

❌ Wrong: 먹는 것 전에

Cannot use 것 with 전에

✅ Correct: 먹기 전에

Must use -기 with 전에

---

❌ Wrong: 가는 것으로 했어요 (for "decided to go")

Wrong pattern for decision

✅ Correct: 가기로 했어요

Must use -기로 하다

---

❌ Unnatural: 수영하기를 좋아해요 (in casual conversation)

Too formal for daily speech

✅ Better: 수영하는 것을 좋아해요

More natural in conversation

Decision Flowchart

Ask yourself:

1. Is it a fixed pattern?

   • 전에, 때문에, -로 하다 → Use -기
   • 같다, 거예요, perception verbs → Use 것

2. Is it formal writing?

   • Yes → Prefer -기
   • No → Prefer 것

3. Does it include a full clause with subject?

   • Yes → Use 것
   • No → Either works

4. Is it conversational?

   • Yes → Prefer 것
   • No → Either works

Quick Reference Table

Context	Use -기	Use 것	Example
Before (전에)	✅	❌	먹기 전에
Because (때문에)	✅	❌	바쁘기 때문에
Seems like (같다)	❌	✅	오는 것 같아요
Going to (거예요)	❌	✅	갈 거예요
Decide to (-로 하다)	✅	❌	가기로 했어요
Like doing (좋아하다)	✅ (formal)	✅ (casual)	Both OK
Is difficult (-가 어렵다)	✅ (common)	△ (less common)	하기가 어려워요
Formal writing	✅	△	Prefer -기
Casual speech	△	✅	Prefer 것

Summary Comparison

Aspect	-기	-(으)ㄴ/는 것
Nature	Abstract, general	Specific, concrete
Formality	More formal	More conversational
Feels like	"The act of X"	"What/that I X"
Best for	Writing, formal speech	Daily conversation
Clause complexity	Simple	Can include full clauses
With 전에	✅ Required	❌ Cannot use
With 같다	❌ Cannot use	✅ Required
With 거예요	❌ Cannot use	✅ Required
Frequency in speech	Less common	More common

Practice Choosing

Situation 1: Casual conversation about hobbies

Question: 취미가 뭐예요?

Better: 음악 듣는 것을 좋아해요 (more natural)
Acceptable: 음악 듣기를 좋아해요 (too formal)

Situation 2: Academic paper

Context: Formal recommendation

Better: 매일 운동하기를 권장합니다 (appropriate formality)
Less good: 매일 운동하는 것을 권장합니다 (acceptable but less formal)

Situation 3: Weather observation

Situation: Looking outside

Only option: 비가 오는 것 같아요 (seems like it's raining)
Cannot say: 비가 오기 같아요 (incorrect)

Situation 4: Making plans

Deciding what to do

Only option: 영화 보기로 했어요 (decided to watch a movie)
Cannot say: 영화 보는 것으로 했어요 (incorrect for this meaning)

Key Takeaways

• ✅ -기: More formal, abstract, used in fixed patterns (전에, 때문에, -로 하다)
• ✅ 것: More conversational, specific, required for certain patterns (같다, 거예요)
• ✅ In conversation: -(으)ㄴ/는 것 is more common and natural
• ✅ In writing: -기 is often preferred for formality
• ✅ Some patterns require one or the other - learn the fixed expressions
• ✅ When both work: Choose based on formality and naturalness
• ✅ 같다 and 거예요: Always use 것
• ✅ 전에 and 때문에: Always use -기

Understanding the difference between -기 and -(으)ㄴ/는 것 will make your Korean sound more natural and help you choose the right form for each situation. Start by learning the fixed patterns that require one or the other, then develop a feel for when both work!