How to Say “I Guess” in Korean Without Sounding Wrong: -나 보다 vs -(으)ㄴ가 보다 vs -인가 보다

Many learners directly translate “I guess” into Korean, but this often sounds unnatural.
In Korean grammar, assumptions are expressed differently depending on the level of certainty.

The most common expressions are -나 보다, -(으)ㄴ가 보다, and -인가 보다.
These forms are often confused because they look similar but are used in different situations.

In this guide, you will clearly understand the difference between them with simple explanations and real examples.

1. What Does “I Guess” Mean in Korean Grammar?

In Korean, “I guess” is used when you make an assumption based on indirect evidence, not a random guess.

It means:

• You are not completely sure
• You have a clue or observation
• You infer something logically

👉 In Korean grammar, this is called inference.

2. Korean “I Guess” Grammar Forms Explained

This section compares the three main Korean “I guess” grammar patterns.

It is essential for understanding the difference between verb, adjective, and noun guessing forms in Korean.

This infographic explains how to use Korean “I guess” grammar patterns (-나 보다, -(으)ㄴ가 보다, -인가 보다) with simple rules and examples.

2.1 -나 보다 (Verb Guessing Pattern)

This explains how to use -나 보다 with verbs in Korean grammar to express assumptions about actions based on evidence.

Structure

Verb stem + -나 보다

Examples (Verb → Form + Meaning)

• 가다 → 가나 보다 (to go → I guess they go / are going)
• 먹다 → 먹나 보다 (to eat → I guess they eat / are eating)
• 오다 → 오나 보다 (to come → I guess they are coming)
• 공부하다 → 공부하나 보다 (to study → I guess they are studying)

Common pattern: used to guess actions or events

2.2 -(으)ㄴ가 보다 (Adjective Guessing Pattern)

This section shows how -(으)ㄴ가 보다 is used for adjective-based guesses in Korean, especially for describing states or conditions.

Structure

Adjective stem + -(으)ㄴ가 보다

Rule (받침 규칙)

• If the adjective stem ends with a vowel → use -ㄴ가 보다
• If the adjective stem ends with a consonant → use -은가 보다

Examples (Form + Meaning)

No final consonant (vowel ending)

• 비싸다 → 비싼가 보다 (to be expensive → I guess it is expensive)
• 크다 → 큰가 보다 (to be big → I guess it is big)
• 바쁘다 → 바쁜가 보다 (to be busy → I guess they are busy)

With final consonant (받침 있음)

• 작다 → 작은가 보다 (to be small → I guess it is small)
• 춥다 → 추운가 보다 (to be cold → I guess it is cold)
• 많다 → 많은가 보다 (to be many → I guess there are many)
  

2.3 -인가 보다 (Noun Guessing Pattern)

This part explains how -인가 보다 is used in Korean grammar to guess identity or classification using nouns.

Structure

Noun + 인가 보다

Examples (Noun → Form + Meaning)

• 학생 → 학생인가 보다 (student → I guess they are a student)
• 의사 → 의사인가 보다 (doctor → I guess they are a doctor)
• 직원 → 직원인가 보다 (staff → I guess they are staff)
• 관광객 → 관광객인가 보다 (tourist → I guess they are a tourist)

Common pattern: used to guess identity or classification

3. How to Use -나 보다 in Real Korean Sentences

This section focuses on how to use -나 보다 naturally in Korean conversation based on real-life evidence and observation.

• 택배가 아직 안 온 걸 보니까 길이 막혔나 봐요.
  (I guess the delivery is delayed because the traffic is heavy.)
• 학생들이 다 나간 걸 보니 수업이 끝났나 봐요.
  (I guess the class is over since all the students have left.)
• 전화가 계속 울리는데 안 받는 걸 보니까 집에 없나 봐요.
  (I guess they’re not home since they’re not answering the phone.)
• 불이 켜져 있는 걸 보니까 아직 일하고 있나 봐요.
  (I guess they’re still working since the lights are on.)
• 문 앞에 신발이 많은 걸 보니 손님이 왔나 봐요.
  (I guess they have guests since there are many shoes at the door.)
• 유니폼을 입은 걸 보니까 같은 팀인가 봐요.
  (I guess they’re on the same team or in the same group since they’re wearing uniforms.)
• 가게 안이 비어 있는 걸 보니까 장사가 잘 안 되나 봐요.
  (I guess business isn’t going well since the store looks empty.)
  
  

4. How to Use -(으)ㄴ가 보다 (Adjective-Based Guessing in Korean)

This section explains Korean adjective guessing grammar -(으)ㄴ가 보다 usage, showing how to describe situations or emotional states.

Examples

• 표정이 밝은 걸 보니까 기분이 좋은가 봐요.
  (I guess they’re in a good mood since they look cheerful.)
• 목소리가 약한 걸 보니 많이 아픈가 봐요.
  (I guess they’re quite sick since their voice sounds weak.)
• 계속 창밖을 보는 걸 보니까 심심한가 봐요.
  (I guess they’re bored since they keep looking out the window.)
• 옷이 얇은 걸 보니까 별로 안 추운가 봐요.
  (I guess it’s not that cold since they’re wearing light clothes.)
• 대답이 느린 걸 보니 바쁜가 봐요.
  (I guess they’re busy since they’re slow to respond.)
• 얼굴이 빨개진 걸 보니까 부끄러운가 봐요.
  (I guess they’re embarrassed since their face turned red.)
• 말을 아끼는 걸 보니 조심스러운가 봐요.
  (I guess they’re being cautious since they’re speaking carefully.)
  
  

5. How to Use -인가 보다 (Noun-Based Guessing in Korean Grammar)

This section covers noun-based inference using -인가 보다 in Korean, commonly used for guessing professions, roles, or identity.

• 가방에 책이 많은 걸 보니까 학생인가 봐요.
  (I guess they’re a student since they have many books in their bag.)
• 명함을 주고받는 걸 보니까 회사원인가 봐요.
  (I guess they’re an office worker since they’re exchanging business cards.)
• 카메라를 들고 다니는 걸 보니 사진작가인가 봐요.
  (I guess they’re a photographer since they’re carrying a camera.)
• 계속 전화를 받는 걸 보니까 바쁜 직업인가 봐요.
  (I guess they have a busy job since they keep answering calls.)
• 외국어로 대화하는 걸 보니 외국인인가 봐요.
  (I guess they’re a foreigner since they’re speaking a foreign language.)
• 유니폼을 입은 걸 보니까 직원인가 봐요.
  (I guess they’re staff since they’re wearing a uniform.)
• 지도를 보는 걸 보니까 관광객인가 봐요.
  (I guess they’re a tourist since they’re looking at a map.)
  
  

6. Korean “I Guess” vs -는 것 같다 vs -(으)ㄹ 것 같다 (Grammar Differences)

This section clarifies the difference between Korean guess expressions and similar grammar patterns like -는 것 같다 and -(으)ㄹ 것 같다.

Learners often confuse these forms when expressing opinion vs assumption vs prediction.

7.1 V-나 보다 vs V-는 것 같다 (Guess vs Opinion)

V-나 보다 is typically used when the speaker makes a guess based on noticeable clues or indirect evidence.

V-는 것 같다 is more flexible and can be used for general impressions, opinions, or guesses, based on evidence or general judgment.

Expression	Meaning	Key Difference	Example
V-나 보다	I guess (with evidence)	based on what you see	불이 꺼진 걸 보니까 집에 없나 봐요. (I guess they’re not home.)
V-는 것 같다	I think / it seems	personal opinion	집에 없는 것 같아요. (I think they’re not home.)

👉 Not sure when to use “-는 것 같다”?
Read the full guide to understand how Korean speakers express opinions, impressions, and guesses in real conversations.

7.2 V-나 보다 vs -(으)ㄹ 것 같다 (Observed Guess vs Broader Prediction)

V-나 보다: I guess based on observable clues or indirect evidence.

-(으)ㄹ 것 같다: I think / it seems / it will probably; used for present or future situations and broader prediction.

Expression	Meaning	Time Focus	Example
V-나 보다	I guess (present/past)	now / already happened	비가 오나 봐요. (I guess it’s raining.)
-(으)ㄹ 것 같다	will probably	future	비가 올 것 같아요. (I think it will rain.)

👉 Struggling with “-(으)ㄹ 것 같다”?
Check out the full guide to learn how to talk about future predictions and uncertainty in Korean.

7. Common Mistakes in Korean “I Guess” Grammar

This section highlights common mistakes learners make when using Korean assumption grammar (-나 보다 / -(으)ㄴ가 보다), especially mixing certainty and guessing.

7.1 Confusing Present Guess and Future Guess (V-나 보다 vs -(으)ㄹ 것 같다)

Learners often mix up these two expressions because both express guessing, but they refer to different time frames.

Examples:

하늘이 흐린 걸 보니까 곧 비가 오나 봐요.
(I guess it’s going to rain soon.)

하늘이 흐려서 비가 올 것 같아요.
(I think it will rain.)

V-나 보다 is used when the guess is based on observable clues or indirect evidence
-(으)ㄹ 것 같다 is commonly used for future predictions.

7.2 Using V-나 보다 Without Clear Evidence

V-나 보다 is usually used when your guess is based on some clue, observation, or indirect context.

It does not always require strong or obvious evidence, but there should be some reason behind the guess.

Examples:

✔ 신발이 없는 걸 보니까 이미 나갔나 봐요. (I guess they already left.)
❌ 이미 나갔나 봐요. (No clear evidence → unnatural in many contexts)

7.3 Overusing “I Guess” Grammar in Certain Situations

Learners sometimes use this grammar even when they are certain about something.

Examples:

✔ 오늘 시험이 있어요. (I know for sure.)
❌ 오늘 시험이 있나 봐요. (Used when you are guessing based on evidence, not when you already know for sure.)

✔ 지금 3시예요. (It is clearly 3 o’clock.)
❌ 지금 3시인가 봐요. (Used when you are inferring or checking.)

This grammar is usually used when the speaker is not certain but has a clue or reason.

8. FAQ: Korean “I Guess” Grammar Questions Answered

This FAQ section explains Korean “I guess” grammar expressions (-나 보다, -(으)ㄴ가 보다, -인가 보다) in clear, concise answers optimized for Google featured snippets.

Q1. What is “I guess” in Korean grammar?

“I guess” in Korean is expressed using -나 보다, -(으)ㄴ가 보다, and -인가 보다, depending on verbs, adjectives, and nouns. It is used when making an assumption based on indirect evidence rather than certainty.

👉 Korean “I guess” = inference from observation or clues.

Q2. What is the difference between -나 보다 and -는 것 같다?

-나 보다 is used when you make a guess based on observable evidence or clues.
-는 것 같다 is used to express a personal opinion or impression and is less evidence-based.

Example:

• 비가 오나 봐요 = I guess it is raining (evidence-based)
• 비가 오는 것 같아요 = I think it is raining (opinion-based)

👉 Key difference: evidence vs opinion.

Q3. When do you use -(으)ㄴ가 보다 in Korean?

You use -(으)ㄴ가 보다 when guessing a state or condition described by an adjective. It expresses how something seems based on observation.

Example:

• 비싼가 봐요 = I guess it is expensive
• 바쁜가 봐요 = I guess they are busy

👉 Used for adjective-based assumptions.

Q4. Can -인가 보다 be used for people and objects?

Yes. -인가 보다 is used with nouns and can refer to people, objects, or situations. It is used to guess identity, role, or category.

Example:

• 학생인가 봐요 = I guess they are a student
• 고장인가 봐요 = I guess it is broken

👉 Used for noun-based identity guessing.

Q5. What is the correct way to say “I guess” in Korean?

There is no single translation for “I guess” in Korean. The correct form depends on grammar type:

• -나 보다 → verbs (actions)
• -(으)ㄴ가 보다 → adjectives (states)
• -인가 보다 → nouns (identity)

👉 Korean “I guess” changes depending on sentence structure.

9. Practice Exercises: Korean “I Guess” Grammar Usage

This section helps learners practice Korean grammar for expressing “I guess” in real sentences using contextual clues and correct endings.

These exercises help you practice how to use Korean “I guess” grammar correctly.

Korean Sentence	English Translation	Options
비가 _ .	I guess it’s raining.	오나 봐요 / 온가 봐요
학생들이 교실에 없어요. 수업이 _ .	I guess class is over.	끝났나 봐요 / 끝난가 봐요
음식이 너무 _ .	I guess the food is expensive.	비싼가 봐요 / 비싸나 봐요
저 사람은 의사___ .	I guess that person is a doctor.	인가 봐요 / 이나 봐요
방이 너무 _ .	I guess the room is small.	작은가 봐요 / 작나 봐요
창문이 열려 있어요. 바람이 _ .	I guess the wind came in.	들어왔나 봐요 / 들어온가 봐요
사람들이 줄 서 있어요. 그 식당이 _ .	I guess that restaurant is popular.	유명한가 봐요 / 유명하나 봐요
불이 다 꺼졌어요. 벌써 _ .	I guess it’s already closed.	닫았나 봐요 / 닫은가 봐요
가방이 무거워 보여요. 많이 _ .	I guess they bought a lot of things.	샀나 봐요 / 산가 봐요
저분은 선생님___ .	I guess that person is a teacher.	인가 봐요 / 이나 봐요

Answers and Explanations

1. 오나 봐요
   This is a verb, so use -나 보다.
2. 끝났나 봐요
   The clue shows a finished situation, so -나 보다 is correct.
3. 비싼가 봐요
   비싸다 is an adjective whose stem ends in a vowel sound, so use -ㄴ가 보다.
4. 인가 봐요
   의사 is a noun, so use -인가 보다.
5. 작은가 봐요
   작다 ends in a consonant, so use -은가 보다.
6. 들어왔나 봐요
   This is a guessed past action based on evidence, so use -나 보다.
7. 유명한가 봐요
   유명하다 is an adjective with a vowel-ending stem, so use -ㄴ가 보다.
8. 닫았나 봐요
   The lights being off suggest a completed action, so use -나 보다.
9. 샀나 봐요
   The heavy bag suggests a past action, so use -나 보다.
10. 인가 봐요
    선생님 is a noun, so use -인가 보다.
    
    

10. Conclusion: How to Speak Natural Korean Using “I Guess” Expressions

Understanding how to say “I guess” in Korean is essential for natural and fluent communication.

By using -나 보다, -(으)ㄴ가 보다, and -인가 보다, you can express assumptions based on real evidence rather than direct guessing. This helps your Korean sound more natural and context-appropriate in everyday conversation.

Mastering the difference between guessing (-나 보다) and intention or possibility forms is especially important for intermediate learners. Once you understand these patterns, you will be able to follow real Korean conversations more easily and express your thoughts more naturally.

11. Related Korean Grammar Guides

Learn how Korean inference, opinion, and assumption expressions are connected in real communication.
These related grammar topics will help you understand nuance differences and choose the most natural expression in context.

👉 Discover more Korean grammar lessons in the Grammar Learning Hub.

📌 Core Grammar Categories

Guessing & Inference Expressions (Essential for Intermediate Learners)

• Difference Between “아/어 보이다” and “-(으)ㄴ/는 것 같다” in Korean (Appearance vs Guess Explained)
• “-나 보다” vs “-는 것 같다”: How to Express “I Guess” Naturally in Korean
• How to Use “-(으)ㄴ/는 모양이다” for Inference in Korean (Meaning and Usage Guide)

👉 These grammar patterns help you understand how Korean speakers express guesses based on appearance, evidence, or context.

Opinion vs Assumption (Nuance Differences)

• “-은/ㄴ 것 같다” vs “-았/었던 것 같다” in Korean (Present vs Past Guess Explained)
• Korean Grammar “-는 것 같다” (How to Express Opinions and Impressions Naturally)
• Korean Grammar “-(으)ㄹ지도 모르다” (How to Express Uncertain Possibility in Korean)

👉 This group focuses on how Korean expresses opinions, impressions, and levels of certainty.