-(으)ㄹ 것 같다 vs -나 보다: What Is the Difference?

Key facts

• -(으)ㄹ 것 같다 expresses a guess or an impression. It can look ahead, soften an opinion, or describe a feeling.
• -나 보다 expresses an inference from evidence the speaker has noticed.
• Do not use -나 보다 for facts that you already know.

What you'll learn

• Say which pattern is a guess and which is an inference from clues.
• Build both patterns for verbs, adjectives and the copula 이다.
• Choose the right pattern for five sentences and give the reason.
• Avoid using -나 보다 for facts you already know.

Before you start: you should know the polite ending -아요/어요 and the modifier endings -는, -(으)ㄴ and -(으)ㄹ (the endings that let a verb describe a noun). The full rules for each pattern are on their own lesson pages, linked below. Audio plays only when you press a button.

What Is the Difference between -(으)ㄹ 것 같다 and -나 보다?

The difference is the basis of the statement. -(으)ㄹ 것 같다 is built on the speaker's own sense of how things look or will turn out. -나 보다 is built on a clue that the speaker has noticed, and the speaker concludes something from it. English covers both with "it seems" or "I think", so the Korean choice needs a new habit.

Here are two sentences about rain.

내일 비가 올 것 같아요. (naeil biga ol geot gatayo) "I think it will rain tomorrow." Pronunciation: [내일 비가 올껃까타요]. The speaker is looking ahead. The sky, the forecast or a feeling may be behind the guess, but the sentence is about something that has not happened yet.

비가 오나 봐요. (biga ona bwayo) "It looks like it's raining." Imagine that you are inside, and you see people come in with wet umbrellas. You have not seen the rain, only its traces, and you conclude that it is raining.

The first sentence points forward. The second sentence reads a present clue. The next section lines the two patterns up in a table.

-(으)ㄹ 것 같다 vs -나 보다: Side-by-Side Table

The table compares the two patterns on the points that decide the choice.

The table needs three notes. First, 것 is the noun "thing" and 같다 means "to be like", so 것 같다 is literally "to be like a thing that...", and it works as a set phrase. Second, 보다 here is the verb "to see", and 나 보다 means "it looks as though". The polite form 봐요 comes from 보아요. Third, the pattern -(으)ㄴ가 보다 is the same idea for adjectives and for 이다, as in 비싼가 봐요 ("it must be expensive").

How Do the Forms Change by Tense?

The two patterns use different modifier endings, and the difference matters because 것 같다 shows time in the modifier.

So -(으)ㄹ 것 같다 is only one member of a family. The -(으)ㄹ form (올, 갈) is the one for guesses about the future. For a guess about what is happening now, the speaker uses 오는 것 같아요 or 비싼 것 같아요.

When Do You Use -(으)ㄹ 것 같다?

Use -(으)ㄹ 것 같다 when you guess about the future, when you give a soft opinion, or when you describe an impression without a clue to point to. The ending depends on the stem: a vowel stem takes ㄹ, a consonant stem takes 을, and a stem that ends in ㄹ keeps it.

Four typical uses follow.

1. A guess about the future. 이 영화는 재미있을 것 같아요. (i yeonghwaneun jaemiisseul geot gatayo) "I think this movie will be fun." Nothing has happened yet, so no clue can be pointed to.
2. A soft opinion. 이게 더 예쁜 것 같아요. (ige deo yeppeun geot gatayo) "I think this one is prettier." Koreans often add 것 같아요 to keep an opinion from sounding too sharp.
3. A feeling or condition of the speaker. 저는 좀 피곤한 것 같아요. (jeoneun jom pigonhan geot gatayo) "I think I'm a little tired."
4. A past event that you only partly remember. 지난달에 만난 것 같아요. (jinandare mannan geot gatayo) "I think we met last month."

The second and third uses show a key point: 것 같다 can be used about things the speaker knows very well, because the "seems" is a way of speaking softly. For the full rules, read the lesson on -(으)ㄹ 것 같다.

When Do You Use -나 보다?

Use -나 보다 when you notice a clue and conclude something from it. The speaker usually did not see the event itself, only its results or traces. Add 나 보다 to the plain stem of a verb, and -(으)ㄴ가 보다 to an adjective or to 이다. The past marker -았/었 goes before 나.

Here are four everyday scenes.

1. Traces of an event. 길이 젖었어요. 비가 왔나 봐요. (giri jeojeosseoyo. biga wanna bwayo.) "The road is wet. It must have rained." The wet road is the clue.
2. A person's behavior. 지금 자나 봐요. 전화를 안 받아요. (jigeum jana bwayo. jeonhwareul an badayo.) "She must be sleeping now. She doesn't answer the phone." The unanswered phone is the clue.
3. A crowd. 이 식당은 맛있나 봐요. 사람이 많아요. (i sikdangeun masinna bwayo. sarami manayo.) "This restaurant must be good. There are many people." Pronunciation: [마신나 봐요].
4. A look at the price. 저 가방은 비싼가 봐요. 아무도 안 사요. (jeo gabangeun bissanga bwayo. amudo an sayo.) "That bag must be expensive. Nobody buys it."

In each scene the first sentence or the second sentence gives the clue. If you can say "I see X, so Y" in English, -나 보다 is probably right. Notice also that the sentence is about someone or something else. When the clue comes from your own body, you can still use it: 감기에 걸렸나 봐요 ("I seem to have caught a cold") is natural, because you noticed the signs and drew a conclusion. For the full rules, read the lesson on -나 보다.

Can You Use Both in the Same Sentence?

Sometimes either pattern is possible, and the difference shows how much evidence you claim. Look at one person.

• 저 사람은 한국 사람인 것 같아요. (jeo sarameun hanguk saramin geot gatayo.) "I think that person is Korean." The impression comes from the way the person looks or acts.
• 저 사람은 한국 사람인가 봐요. (jeo sarameun hanguk saraminga bwayo.) "That person seems to be Korean." You heard the person speak Korean on the phone, so there is a specific clue.

Both sentences are fine. The first gives a hunch, and the second says "I have evidence". Another contrast is direct perception. When you see the rain with your own eyes, the natural sentence is 비가 오네요 ("Oh, it's raining"), not 비가 오나 봐요. The ending -네요 marks something you notice right now. The family of endings for noticing things is wide, so this page keeps to the contrast between 것 같다 and 나 보다.

Which One Should You Pick? a Simple Rule of Thumb

Ask three questions in order.

1. Are you talking about the future? If yes, use -(으)ㄹ 것 같다. -나 보다 does not fit the future. Example: 내일 눈이 올 것 같아요.
2. Are you giving an opinion or softening a statement? If yes, use 것 같다. Example: 이 방법이 더 쉬운 것 같아요.
3. Can you point to a sign that you noticed? If yes, use -나 보다 for a verb, or -(으)ㄴ가 보다 for an adjective or 이다. Example: 불이 꺼져 있어요. 집에 없나 봐요. ("The lights are off. He must not be home.")

If you cannot point to a sign, choose 것 같다. It works in almost every case where -나 보다 does not.

What Mistakes Do Learners Make with These Two?

The commonest mistakes come from using one pattern in the other's territory. Five of them appear again and again.

1. Using -나 보다 for a fact you know. 오늘은 월요일인가 봐요 is odd when you know that it is Monday. Say 오늘은 월요일이에요. Use 나 보다 only for things that you are inferring.
2. Using -나 보다 about the future. 내일 비가 오나 봐요 does not mean "it will rain tomorrow". Say 내일 비가 올 것 같아요.
3. Using -(으)ㄹ 것 같다 for the present. 지금 먹을 것 같아요 means "I think I will eat" or "he will probably eat", not "he seems to be eating". For the present, say 먹는 것 같아요.
4. Using the verb form on an adjective. Learners often say 비싸나 봐요. Textbooks teach -(으)ㄴ가 보다 for adjectives, so say 비싼가 봐요. (비싸나 봐요 is also heard in speech, but the -(으)ㄴ가 form is the safe choice.)
5. Writing 것 같다 without a space. Write 올 것 같아요, not 올것같아요. 것 is a separate word.

A quick self-check: translate your sentence with "I see that..." first. If "I see..." fits, use 나 보다. Then check the time. If it is the future, switch to 것 같다.

Practice: Choose the Right Pattern

Try the five questions, then read the answers below.

Answer key

1. 오나 봐요. The sentence is 밖에 비가 오나 봐요.
2. 내일 눈이 올 것 같아요.
3. 비싼가 봐요. The sentence is 저 가방은 비싼가 봐요.
4. 이게 더 좋은 것 같아요.
5. The first option sounds wrong, because the speaker already knows the fact.

Now write your own pair: one guess about tomorrow's weather with -(으)ㄹ 것 같다, and one inference from a clue in your room with -나 보다.

What Should You Learn Next?

After this comparison, study each pattern on its own lesson page, then look at the other pairs on the list.

1. Learn the full rules for -(으)ㄹ 것 같다, including the present and past forms.
2. Learn the full rules for -나 보다, including the past and the adjective form.
3. Read the other guessing pair, -(으)ㄹ 텐데 vs -(으)ㄹ 것 같다.
4. Compare other confusable pairs on Confusing Grammar Compared.
5. See where both patterns sit on the Intermediate Grammar list.

Frequently Asked Questions

What Is the Difference between -(으)ㄹ 것 같다 and -나 보다?

-(으)ㄹ 것 같다 expresses a guess or an impression, and it can also soften an opinion or look ahead to the future. -나 보다 expresses an inference from clues that the speaker has noticed, and it points to a present or past situation. The first can stand alone, but the second needs a visible sign.

Can I Always Replace -(으)ㄹ 것 같다 with -나 보다?

No. For the future, an opinion or a polite hedge, only 것 같다 works: 이게 더 좋은 것 같아요 (I think this is better). For a guess based on traces, such as a wet street, 비가 왔나 봐요 is natural and 비가 온 것 같아요 is also possible, with a weaker sense of evidence.

Which One Sounds More Natural in Speech?

것 같다 is the more common of the two, because it covers future guesses, opinions and polite softening. -나 보다 is also common in conversation, but only when the speaker has noticed a clue. Both are used in polite speech, and neither belongs only to writing.

Which One Appears More Often on TOPIK?

This site does not publish exam statistics. Both patterns are taught at the intermediate stage. For current exam content, check the level descriptions and past papers on the official TOPIK site, topik.go.kr.

What Is the Quickest Rule to Remember?

Ask yourself whether you can point to a sign. If you can say "because I see or hear this", use -나 보다. If you are thinking ahead, giving an opinion or being polite, use -(으)ㄹ 것 같다.

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