-(으)ㄹ지도 모르다 Grammar in Korean: Meaning and How to Use It

What you'll learn

• Attach -(으)ㄹ지도 모르다 to vowel stems, consonant stems, ㄹ stems and common irregular stems.
• Warn someone about a possibility with 올지도 몰라요 and 늦을지도 몰라요.
• Say "might have" with 갔을지도 몰라요 and keep the tense off 모르다.
• Tell apart 올지도 몰라요 ("he might come") from 올지 몰라요 ("I do not know if he will come").

Before you start: you should know how to find a stem (drop 다 from the dictionary form) and the polite ending -아요/어요. Audio plays only when you press a button.

What Does -(으)ㄹ지도 모르다 Grammar Mean?

-(으)ㄹ지도 모르다 grammar means "might" or "may." It states a possibility, and the speaker is open about being unsure. Think of it as "There is a chance, but I cannot tell." If a friend asks, "Will Min-su come?", 올지도 몰라요 says, "He might. I really don't know."

The pattern is built from three small parts. The first is -(으)ㄹ지, an ending that holds a question inside a sentence ("whether it will..."). The second is 도, a particle that usually means "also" but here adds the sense "even." The third is 모르다 ("to not know"). Together, the words say something close to "I do not even know whether it will happen," and the listener understands "so it could happen." That is why the particle 도 here does not mean "also."

Here are the first two examples.

• 그 사람이 올지도 몰라요. (geu sarami oljido mollayo.) [그 사라미 올찌도 몰라요] = "He might come."
• 내일은 눈이 올지도 몰라요. (naeireun nuni oljido mollayo.) [내이른 누니 올찌도 몰라요] = "It might snow tomorrow."

Notice the sound. After the ending ㄹ, the ㅈ of 지 becomes tense, so you hear [찌], and the whole word sounds like [올찌도]. This follows the tensing rule of the standard pronunciation rules (표준 발음법, Article 27) of the 국립국어원 (National Institute of Korean Language). You still write 지. The Revised Romanization does not show tensing caused by a neighbouring sound, so it reads oljido. Next comes the mechanism that builds the pattern.

How Do You Form -(으)ㄹ지도 모르다?

-(으)ㄹ지도 모르다 is formed by dropping 다 from the dictionary form and adding -ㄹ지도 모르다 after a vowel or ㄹ, or -을지도 모르다 after any other final consonant. The (으) in brackets is a linking vowel that appears only when it is needed. The final word 모르다 is a 르-irregular verb, so the polite form is 몰라요, not 모르아요.

The table shows one idea: a vowel stem gets a final ㄹ, and a consonant stem gets 을. The next three parts take the groups one at a time.

Stems Ending in a Vowel

A vowel stem takes the ending by adding ㄹ to the last syllable. 오 becomes 올, 가 becomes 갈, and 비싸 becomes 비쌀. Then you add 지도 모르다.

• 비가 올지도 몰라요. (biga oljido mollayo.) [비가 올찌도 몰라요] = "It might rain."
• 그 책은 비쌀지도 몰라요. (geu chaegeun bissaljido mollayo.) [그 채근 비쌀찌도 몰라요] = "That book might be expensive."

Vowel stems are the simplest case. A stem with a final consonant needs one extra vowel.

Stems Ending in a Consonant

A stem with a final consonant takes 을 before 지도. 늦다 becomes 늦을지도 모르다, 없다 becomes 없을지도 모르다, and 닫다 becomes 닫을지도 모르다.

• 지금 가면 늦을지도 몰라요. (jigeum gamyeon neujeuljido mollayo.) [지금 가면 느즐찌도 몰라요] = "If we go now, we might be late."
• 다음 주에 시간이 없을지도 몰라요. (daeum jue sigani eopseuljido mollayo.) [다음 주에 시가니 업쓸찌도 몰라요] = "I might not have time next week."

The final consonant of the stem links to 을, so 늦을 is pronounced [느즐]. The word 없을 is pronounced [업쓸] because the ㅅ after ㅂ becomes tense. Now for stems that change shape.

Irregular Stems and Nouns

Irregular stems change as usual before a vowel, and ㄹ stems keep their ㄹ:

• ㅂ-irregular: 춥다 becomes 추울지도 모르다, and 어렵다 becomes 어려울지도 모르다: 시험이 어려울지도 몰라요 ("The exam might be hard").
• ㄷ-irregular: 듣다 becomes 들을지도 모르다: 그 소식을 들을지도 몰라요 ("He might hear that news").
• 르-irregular: 모르다 becomes 모를지도 모르다: 민수 씨는 모를지도 몰라요 ("Min-su might not know").
• ㄹ stems: 멀다 becomes 멀지도 모르다 and 살다 becomes 살지도 모르다. No 을 is added: 이 길이 더 멀지도 몰라요 ("This road might be farther").
• Nouns with 이다: add 일지도 모르다. 그 사람은 학생일지도 몰라요 means "He might be a student."

The same sound rule applies to every example: after ㄹ the ㅈ of 지도 is tense. With the formation clear, one full sentence can be built step by step.

Worked Example: Building a Sentence with -(으)ㄹ지도 모르다

-(으)ㄹ지도 모르다 grammar turns a plain statement into a possibility. Follow the steps with "I am late." The sentence uses a consonant stem, so the extra 을 appears.

1. Start with the plain sentence. 저는 늦어요. (jeoneun neujeoyo.) = "I am late." The predicate is 늦어요.
2. Find the dictionary form. 늦어요 comes from 늦다 (to be late). The stem is 늦.
3. Look at the end of the stem. 늦 ends in a consonant, so you add 을: 늦 + 을 = 늦을.
4. Add 지도 모르다. 늦을 + 지도 모르다 = 늦을지도 모르다.
5. Choose the speech level. For polite speech, change 모르다 into 몰라요. Result: 저는 늦을지도 몰라요. (jeoneun neujeuljido mollayo.) = "I might be late."

You will know it worked when the stem is followed by 을 or ㄹ before 지도, and the last word is 몰라요. The most common slip at this step is writing 몰라요 as 모르아요 or 모르어요. 모르다 is a 르-irregular verb, so the polite form is always 몰라요. The sentence is now a possibility. A possibility can appear in several tenses and sentence types, and each has limits.

Which Tenses and Sentence Types Work with -(으)ㄹ지도 모르다?

-(으)ㄹ지도 모르다 works for statements about the present state, the future or the past. The only tense you can show is the past, with -았/었- placed before 지도. The last word 모르다 always stays in the present. The table shows the forms for 가다 in the polite style.

Do not move the tense onto 모르다 when you guess now about a past event. 올지도 몰랐어요 places the possibility itself in the past: "At that time, there was a chance he would come." For a guess you make now about something that may already have happened, put 았/었 on the main verb: 왔을지도 몰라요.

The pattern is for statements. A question with it is unusual, so for "Do you think he will come?" use 올까요? instead. The negative can sit before the verb (안 올지도 몰라요) or on the verb (오지 않을지도 몰라요). Both are fine.

• 그 식당은 문을 닫았을지도 몰라요. (geu sikdangeun muneul dadasseuljido mollayo.) [그 식땅은 무늘 다다쓸찌도 몰라요] = "That restaurant might have closed."
• 우산을 가져가세요. 비가 올지도 몰라요. (usaneul gajyeogaseyo. biga oljido mollayo.) = "Take an umbrella. It might rain."

The second example shows the most common real use, a friendly warning. The next section compares the pattern with the one that looks most like it.

How Is -(으)ㄹ지도 모르다 Different from -(으)ㄹ 수도 있다?

-(으)ㄹ지도 모르다 puts the focus on the speaker's own uncertainty, while -(으)ㄹ 수도 있다 says that the situation allows something. In many sentences, you can swap them without changing the meaning. The difference is a matter of emphasis.

The second pattern uses 수 ("way, ability"), so 올 수 있어요 without 도 means "He can come." The 도 turns it into a possibility. Full rules are on the page for -(으)ㄹ 수도 있다.

A second neighbour is -(으)ㄹ 것 같다, which means "I think it will." It is more positive: 올 것 같아요 leans toward "he will come," while 올지도 몰라요 only opens the door. The opposite pole is -(으)ㄹ 리가 없다, which strongly denies a possibility ("there is no way").

For firm forecasts, Korean uses future guess -겠- or future tense -(으)ㄹ 거예요. Those pages cover them in full. Now for variations you will hear in real talk.

Variations and Edge Cases of -(으)ㄹ지도 모르다

-(으)ㄹ지도 모르다 has a few common variations. They differ mostly in what follows the pattern.

• With -니까 for a reason. Add -(으)니까 to 모르다 to give a reason for a request: 비가 올지도 모르니까 우산을 가져가세요 ("It might rain, so take an umbrella"). The sound is [올찌도 모르니까].
• With 모르겠어요. Replace 몰라요 with 모르겠어요 for a softer, more thoughtful tone: 올지도 모르겠어요. It sounds like thinking aloud.
• With 어쩌면 or 혹시. The adverbs 어쩌면 ("perhaps") and 혹시 ("by any chance") often come first: 어쩌면 비쌀지도 몰라요. They strengthen the sense of an open question.
• First-person warnings. People often use the pattern about themselves: 제가 좀 늦을지도 몰라요 ("I might be a little late"). It is a polite way to prepare someone for a possible change.
• Honorific -(으)시-. Place it before 지도 when the subject deserves respect: 선생님도 오실지도 몰라요 ("The teacher might come too").

This lesson covers the spoken guess and its main variants. It does not cover the formal written style in depth. The mistakes below show where learners go wrong.

What Mistakes Do Learners Make with -(으)ㄹ지도 모르다?

Learners most often misread 도, drop it, or move the tense. Four slips come up again and again.

1. Reading 도 as "also." 올지도 몰라요 does not mean "I also don't know if he'll come." The pattern is one fixed unit meaning "might."
2. Dropping 도. 올지 몰라요 means "I do not know whether he will come." It is usually a statement about your knowledge, not about a possibility. Some written Korean uses -(으)ㄹ지 모른다 for "may" as well, but with 도 the meaning is always clear.
3. Using a past form of 모르다. For "He might have gone," put the past marker on the main verb and keep 몰라요: 갔을지도 몰라요. Changing 몰라요 to 몰랐어요 moves the possibility itself into the past.
4. Using it for something you know. If you are sure, do not say 올지도 몰라요. Say 올 거예요 or 와요.

A quick check for any sentence: Is it only a possibility? Is the main verb followed by ㄹ or 을 and then 지도? Does the last word say 몰라요 in the present? If all three answers are yes, the sentence is sound.

The practice set below tests these points directly.

Practice and Answers

Try the items before you read the answer key.

1. Build the form. Write the polite -(으)ㄹ지도 모르다 form of 춥다 ("to be cold").
2. Fix the error. A learner says 친구가 갔을지도 몰랐어요 for "My friend might have gone." Correct it.
3. Choose the form. Which says "I do not know whether it will rain": 비가 올지 몰라요 or 비가 올지도 몰라요?
4. Write your own. Write one warning for a friend about tomorrow, using -(으)ㄹ지도 몰라요.

Answer key

1. 추울지도 몰라요. 춥다 is ㅂ-irregular. The ㅂ becomes 우 and then ㄹ is added: 추울.
2. 친구가 갔을지도 몰라요. The past marker is on 갔, and 모르다 stays in the present.
3. 비가 올지 몰라요. Without 도, the sentence is usually about not knowing. With 도, it means "It might rain."
4. Answers vary. Check that the stem is followed by ㄹ or 을, then 지도 몰라요. An example: 내일은 길이 막힐지도 몰라요. ("The roads might be jammed tomorrow.")

If you can answer items 1 to 3 without the key, you can use the pattern in conversation. Next, the lesson points to related patterns.

What Should You Learn Next after -(으)ㄹ지도 모르다 Grammar?

After -(으)ㄹ지도 모르다 grammar, learn the close partner for possibility, then the strong denial. This lesson teaches one pattern for a tentative possibility and does not cover firm forecasts or plans.

1. Start with -(으)ㄹ 수도 있다, the near-twin for "it is possible."
2. Continue with -(으)ㄹ 리가 없다, the strong denial.
3. Review the neutral guess -(으)ㄹ 것 같다, then the future with future guess -겠- and future tense -(으)ㄹ 거예요.
4. Return to Guessing and Conjecture to see every lesson in this set, or to the Intermediate Grammar list for other B1 patterns.

With these steps, the pattern becomes automatic: take the stem, add ㄹ or 을, then 지도 몰라요, and keep 몰라요 in the present.

Frequently Asked Questions

What does -(으)ㄹ지도 모르다 mean?

-(으)ㄹ지도 모르다 means "might" or "may." It says something is possible, but the speaker is far from sure. 그 사람이 올지도 몰라요 means "He might come." Word for word it is close to "I do not even know if he will come," which is why it feels so tentative and open-ended.

How do I attach -(으)ㄹ지도 모르다 to a verb or adjective?

Drop 다 from the dictionary form. After a vowel or ㄹ, add -ㄹ지도 모르다: 오다 becomes 올지도 모르다, and 멀다 becomes 멀지도 모르다. After another final consonant, add -을지도 모르다: 늦다 becomes 늦을지도 모르다. Nouns use 이다, as in 학생일지도 몰라요.

Can -(으)ㄹ지도 모르다 be used in the past tense?

Yes, but put the past marker before the ending and keep 모르다 in the present. 갔을지도 몰라요 means "He might have gone." If you change the end to 몰랐어요, the possibility itself moves into the past, so 올지도 몰랐어요 means "At that time, there was a chance he would come." It is not a guess you make now about a past event.

Is -(으)ㄹ지도 모르다 used in speech or only in writing?

Both. In daily talk, people say 올지도 몰라요 or the shorter 올지도 몰라. In formal speech they say 올지도 모릅니다, and in careful writing they use 올지도 모른다. A softer spoken variant is 올지도 모르겠어요. The possibility meaning is the same at every level.

What is the most common mistake with -(으)ㄹ지도 모르다?

The most common mistake is reading 도 as "also" and 모르다 as a plain "do not know." 올지도 몰라요 does not mean "I also do not know whether he will come." It means "He might come." A second slip is dropping 도, which in speech usually changes the meaning to "I do not know whether he will come."

Can I use -(으)ㄹ지도 모르다 about myself?

Yes. 제가 늦을지도 몰라요 means "I might be late," and it is a very natural warning. You can use it for your own possible actions or states when you are not sure, as long as you describe a possibility and not a decision. For a decided plan, use -(으)ㄹ 거예요.

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