-(으)ㄹ까 봐 Grammar in Korean: Meaning and How to Use It

What you'll learn

• Attach -(으)ㄹ까 봐 to vowel stems, consonant stems, ㄹ stems and irregular stems.
• Tell a feared possibility from a fact.
• Use -았/었을까 봐 for a worry about something that may have happened.
• Choose between -(으)ㄹ까 봐, -기 때문에 and -(으)니까.

Prerequisites: the polite ending -아요/어요, the past tense -았/었- and -(으)니까. Time: about 15 minutes.

Listen to two model sentences.

The next section defines the pattern.

What Does -(으)ㄹ까 봐 Grammar Mean?

-(으)ㄹ까 봐 means "worried that" or "in case". A connective ending is a word ending that joins one clause to the next. This one tells the listener, "I did the next thing because something bad might happen."

The key word is "might". In the first clause, the event has not happened, or the speaker does not know whether it has. The speaker only fears it. The second clause shows the result of that fear: a precaution the speaker took, or a feeling such as worry.

The ending has two parts. -(으)ㄹ까 is the "I wonder if..." ending, as in 비가 올까요? ("Will it rain?"). 봐 comes from 보다, "to see", and in this pattern it means roughly "it seems". Together they give "I wonder if it will rain, and so...". You do not need to translate the parts. Learn the whole ending as one unit.

Here are two glossed examples.

The main clause comes in two kinds. One is a precaution, as in both examples above. The other is a feeling: 시험에 떨어질까 봐 걱정돼요 means "I am worried I will fail the exam."

The next section shows how to build the form.

How Do You Form -(으)ㄹ까 봐?

Remove 다 from the dictionary form to get the stem. Then look at the last sound of the stem.

• If the stem ends in a vowel, add ㄹ to the last syllable and then 까 봐: 오 + ㄹ까 봐 = 올까 봐.
• If the stem ends in a consonant, add 을까 봐: 먹 + 을까 봐 = 먹을까 봐.
• If the stem ends in ㄹ, keep the ㄹ and add 까 봐: 살 + 까 봐 = 살까 봐.

The ㄹ of the ending is written under the last vowel, so "오 + ㄹ" becomes one block, 올. Standard spacing writes 봐 as a separate word: 올까 봐. In chat you will often see 올까봐, but the spaced form is standard.

Look at the spoken forms. After 먹, 읽 and 많, the 을 joins the final consonant, so 먹을까 sounds like [머글까]. The ㅎ of 많 is silent before a vowel. In 있을까, the ㅆ moves to the next syllable and 을 follows: [이쓸까]. The tense ㄲ in 까 is already in the spelling, so RR writes it as kk in every form.

Stems Ending in a Vowel

A vowel stem takes ㄹ and joins it to the last syllable: 갈까 봐, 올까 봐, 할까 봐, 아플까 봐. For 하다 words, write 할까 봐: 피곤할까 봐 ("afraid of being tired").

Stems Ending in a Consonant

A consonant stem takes 을까 봐: 먹을까 봐, 잃을까 봐, 늦을까 봐. The 을 is a helping vowel plus ㄹ. It stops the stem and ㄹ from piling up.

Irregular Stems and Nouns

Irregular stems follow the same changes as before any ending that begins with a vowel sound. The ㅂ-irregular and ㄷ-irregular stems change, and the ㄹ stem keeps its ㄹ.

For nouns, use 이다, which means "to be". The form is 일까 봐 after any noun: 학생일까 봐 and 의사일까 봐. These forms are used less often. Most sentences have a verb or adjective in the first clause.

The next section builds a full sentence.

Worked Example: Building 비가 올까 봐 우산을 가져왔어요

Say "I brought an umbrella in case it rains." Follow five steps.

1. Name the feared event. "It rains" is 비가 오다.
2. Find the stem. Remove 다 from 오다 to get 오.
3. Add ㄹ까 봐. 오 ends in a vowel, so the ㄹ joins the syllable: 올. Then add 까 봐: 올까 봐.
4. Write the precaution. "I brought an umbrella" is 우산을 가져왔어요 in the polite past.
5. Join the two parts. 비가 올까 봐 우산을 가져왔어요.

You'll know it worked when the first part ends in 까 봐 and the second part shows what you did about the fear. Try the same steps with "I left early because I was afraid of being late": 늦다 gives 늦을까 봐, and 일찍 나왔어요 follows.

The next section covers tense and sentence types.

Which Tenses and Sentence Types Work with -(으)ㄹ까 봐?

The ending itself has a fixed possibility meaning. Of the tense markers, only the past can be added before it. The main clause cannot be a command or a suggestion. For advice about a precaution, use -(으)ㄹ지도 모르니까: 비가 올지도 모르니까 우산을 가져가세요 ("It might rain, so take an umbrella").

Look at the past form. The marker 았/었 sits before 을까 봐: 화나 + ㅆ + 을까 봐 = 화났을까 봐. Use it only when you do not know whether the event has happened. 친구가 화났을까 봐 전화했어요 means "I called because I was afraid my friend might have got angry." The speaker does not know if the friend is angry.

Yes/no questions end with a rise. A wh-question puts the stress on the question word and often ends with a fall or a rise-fall, rather than a sharp rise: 왜 우산을 가져왔어요? asks "Why did you bring an umbrella?"

The honorific 시 goes before ㄹ까 봐 when the person in the worry deserves respect: 어머니가 걱정하실까 봐 말씀 안 드렸어요 means "I did not tell my mother, because I was afraid she would worry." The past tense has its own page: past tense -았/었-.

The next section compares -(으)ㄹ까 봐 with its neighbours.

How Is -(으)ㄹ까 봐 Different from -기 때문에?

All three endings can be translated as "because". The difference is how the speaker sees the reason: as a fact or as a fear.

Compare two sentences about the same umbrella.

• 비가 오니까 우산을 가져가세요. ("It is raining, so take an umbrella.") The rain is a fact.
• 비가 올까 봐 우산을 가져왔어요. ("I brought an umbrella in case it rains.") The rain is only a possibility.

A useful test is to ask whether the event could still fail to happen. If yes, -(으)ㄹ까 봐 is possible. If the event is certain, use -기 때문에 or -(으)니까. See -기 때문에 and -(으)니까 for the two fact-based endings.

The next section covers short answers and spacing.

Variations and Edge Cases of -(으)ㄹ까 봐

The Short Answer: -(으)ㄹ까 봐요

Adding 요 lets the clause stand alone. It answers a why-question and implies the rest. 왜 우산을 가져왔어요? 비가 올까 봐요. means "Why did you bring an umbrella? In case it rains." The listener understands the rest.

A Longer Form: -(으)ㄹ까 봐서

You may hear -(으)ㄹ까 봐서 as a longer form of the same ending: 잊어버릴까 봐서 메모했어요 ("I wrote a memo because I was afraid I would forget"). The meaning stays the same. The shorter form is more common.

Feelings That Go with It

The main clause often contains 걱정되다 ("be worried"), 걱정하다 ("worry"), 무섭다 ("be scary"), 겁나다 ("be scared") or 불안하다 ("be anxious"). The polite form of 걱정되다 is 걱정돼요 [걱쩡돼요], because 되 + 어요 contracts to 돼요.

Spacing

Write 봐 as a separate word: 올까 봐, 늦을까 봐. In messages you will meet the joined form, but in school and in writing the spaced form is standard.

Formal Writing

In formal writing, Korean often uses other patterns for worries, such as -(으)ㄹ 우려가 있어서 or -(으)ㄹ지 몰라서. For everyday Korean, -(으)ㄹ까 봐 is enough.

The next section lists the mistakes that appear most often.

What Mistakes Do Learners Make with -(으)ㄹ까 봐?

Learners make seven predictable mistakes. Each has a reason and a fix.

Learners often use it for a certain fact. Wrong: 비가 왔을까 봐 우산을 가져왔어요, when it is already raining. Right: 비가 오니까 우산을 가져왔어요. Fix: if you can see the rain, use -(으)니까 or -기 때문에.

Learners often add a second ㄹ to a ㄹ stem. Wrong: 살을까 봐 and 만들을까 봐. Right: 살까 봐 and 만들까 봐. Fix: a stem that ends in ㄹ takes 까 봐 directly.

Learners often forget the ㅂ change. Wrong: 춥을까 봐. Right: 추울까 봐. Fix: ㅂ-irregular stems become 우 before a vowel sound.

Learners often leave out the ㄹ. Wrong: 오까 봐 and 가까 봐. Right: 올까 봐 and 갈까 봐. Fix: the ㄹ must be written under the last syllable of a vowel stem.

Learners often join 봐 to the verb. Standard spelling keeps 봐 as its own word: 올까 봐, not 올까봐.

Learners often confuse it with -(으)ㄹ까요? 비가 올까요? asks "Will it rain?" 비가 올까 봐 means "in case it rains". Fix: 까요 asks a question or makes an offer, and 까 봐 gives a reason.

Learners often write a main clause that has no link to the worry. Wrong: 비가 올까 봐 기분이 좋아요. Right: 비가 올까 봐 걱정돼요. Fix: the second clause should be a precaution or a worried feeling.

The next section gives you practice.

Practice and Answers

Do the four tasks, then compare with the key.

Task 1: join the sentences with -(으)ㄹ까 봐. Write one sentence for each pair.

1. 늦다 / 택시를 탔어요.
2. 길을 잃다 / 지도를 봤어요.
3. 감기에 걸리다 / 따뜻하게 입었어요.
4. 시험에 떨어지다 / 걱정돼요.

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

1. 춥을까 봐 코트를 입었어요.
2. 비가 올까 봐 기분이 좋아요.
3. 늦을까봐 택시를 탔어요.

Task 3: translate. Write in Korean: "I wrote a memo because I was afraid I would forget." and "I did not tell my mother because I was afraid she would worry."

Task 4: write your own. Write one sentence about a precaution you take, and one about a worry you feel.

Answer key

1. (1) 늦을까 봐 택시를 탔어요. (2) 길을 잃을까 봐 지도를 봤어요. (3) 감기에 걸릴까 봐 따뜻하게 입었어요. (4) 시험에 떨어질까 봐 걱정돼요.
2. (1) 추울까 봐 코트를 입었어요. (2) 비가 올까 봐 걱정돼요. (3) 늦을까 봐 택시를 탔어요.
3. 잊어버릴까 봐 메모했어요. 어머니가 걱정하실까 봐 말씀 안 드렸어요. Other correct versions exist, for example 엄마가 걱정할까 봐 말 안 했어요.
4. Sample answers: 놓칠까 봐 일찍 나왔어요. 길이 막힐까 봐 걱정이에요. Any pair is correct if the first clause ends in ㄹ까 봐 or 을까 봐 and the second clause is a precaution or a feeling.

If task 1 was correct, you have the formation rule. If task 2 was hard, check whether the second clause really links to the worry. The next section points you to what comes after this lesson.

What Should You Learn after -(으)ㄹ까 봐 Grammar?

After -(으)ㄹ까 봐, learn -거든, a reason given as background information. Review -기 때문에 and -(으)니까 if the fact-based endings still feel unsure.

For a wider view, the parent page Cause and Reason lists every connector in this group. To plan by level, use Intermediate Grammar.

This lesson covers -(으)ㄹ까 봐 in the polite and casual styles. It does not cover every formal variation. About this page. Last updated 2026-10-09. Revised Romanization follows the national rules and is shown only as a learning aid.

Frequently Asked Questions

What Does -(으)ㄹ까 봐 Mean?

-(으)ㄹ까 봐 means "worried that" or "in case". The reason is something the speaker fears might happen, not something that is certain. 비가 올까 봐 우산을 가져왔어요 means "I brought an umbrella in case it rains." The main clause tells what the speaker did or feels because of the worry.

How Do I Attach -(으)ㄹ까 봐 to a Verb or Adjective?

Take the stem. After a vowel, add ㄹ까 봐 so the ㄹ sits under the last syllable: 오 becomes 올까 봐. After a final consonant, add 을까 봐: 먹을까 봐. A stem ending in ㄹ keeps it: 살까 봐. ㅂ-irregular stems turn into 우 first: 춥다 becomes 추울까 봐.

Can -(으)ㄹ까 봐 Be Used in the past Tense?

Yes, as -았/었을까 봐. Use it when the speaker worries about something that may already have happened, such as 친구가 화났을까 봐 전화했어요, "I called because I was afraid my friend might have got angry." It is not used when the speaker already knows the fact.

Is -(으)ㄹ까 봐 Used in Speech or Only in Writing?

It is mostly spoken and very common in conversation. It sounds natural in polite and casual speech. With 요, it can answer a question: 왜 우산을 가져왔어요? 비가 올까 봐요. In formal writing, people often choose other forms such as -(으)ㄹ 우려가 있어서 or -(으)ㄹ지 몰라서.

What Is the Most Common Mistake with -(으)ㄹ까 봐?

The most common mistake is using it for a fact that has certainly happened or will certainly happen, such as 비가 왔을까 봐 우산을 가져왔어요 when it is already raining. The pattern needs real doubt. Other common mistakes are 살을까 봐 for a ㄹ stem and 올까봐 without a space.

What Is the Difference between -(으)ㄹ까 봐 and -기 때문에?

-기 때문에 states a reason that is a fact: 비가 오기 때문에 취소했어요. -(으)ㄹ까 봐 gives a possibility that worries the speaker: 비가 올까 봐 취소했어요 means "I cancelled it in case it rains." Use -(으)ㄹ까 봐 when the event may not happen at all.

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