Key Facts
- Hangul: 알다 (alda)
- Meaning: to know
- Level: A1
- Stem: 알
- Conjugation class: ㄹ-drop
- Object marking: transitive
What Does 알다 Mean?
Unlike English, 알다 is used for people too: 그 사람을 알다 is 'to know that person'. The thing or person known takes 을/를. In a reply, 알겠어요 or 알았어요 means 'I understand' or 'got it', which is a different job from knowing a fact.
Three habits make 알다 easy to use. First, remember that the ㄹ vanishes only in a few predictable places, so 아는 and 아세요 are not exceptions you must memorise one by one. Second, keep 알겠어요 and 알았어요 ready for replies to instructions. Third, do not build the everyday negative with 안: switch to 모르다 and say 몰라요. Together these cover most real conversations that involve knowing something.
How Do You Pronounce 알다?
알다 is read as written, with a clear l at the end of the first syllable. Before a vowel that ㄹ moves over and becomes a light tap, so 알아요 sounds like [아라요]. The formal 압니다 is read [암니다], because ㅂ before ㄴ becomes m.
How Do You Use 알다 in a Sentence?
저는 그 사람을 알아요.
I know that person.
알아요 with 그 사람을: knowing a person means being acquainted with him or her.
내일이면 결과를 알 거예요.
You will know the result by tomorrow.
알 거예요 predicts future knowledge. 내일이면 means 'by tomorrow', and the result is the object.
아는 사람이 많아요.
I have many acquaintances.
아는 before 사람 turns the verb into a description: 'people I know', which the English gloss renders as acquaintances.
How Does Alda Conjugation Work?
알 ends in ㄹ, and this ㄹ disappears before ㄴ, ㅂ and ㅅ. That is why the formal present is 압니다 (not 알ㅂ니다), the honorific is 아세요, and the present modifier is 아는. Before vowel endings and endings such as -고 and -면 the ㄹ stays: 알아요, 알았어요, 알고, 알면. Like all ㄹ stems, 알다 never adds the extra vowel eu, so 'if you know' is 알면.
알다
| Form | Korean | Romanization | Rule |
|---|---|---|---|
| Polite present | 알아요 | ||
| Polite past | 알았어요 | ||
| Polite future (plan) | 알 거예요 | ||
| Polite future (intention or guess) | 알겠어요 | ||
| Formal present | 압니다 | ||
| Formal past | 알았습니다 | ||
| Formal future | 알 것입니다 | ||
| Casual present | 알아 | ||
| Casual past | 알았어 | ||
| Casual future | 알 거야 | ||
| Want to (polite) | 알고 싶어요 | ||
| Honorific polite | 아세요 | ||
| Because / and then | 알아서 | ||
| If (conditional) | 알면 | ||
| Present modifier (before a noun) | 아는 | ||
| Past modifier (before a noun) | 안 | ||
| Future modifier (before a noun) | 알 | ||
| Negative with 안 (short) | 안 알아요 | ||
| Negative (long form) | 알지 않아요 |
Sound Changes
| Form | Korean | Sounds like |
|---|---|---|
| Polite present | 알아요 | [아라요] |
| Polite past | 알았어요 | [아라써요] |
| Polite future (plan) | 알 거예요 | [알꺼예요] |
| Polite future (guess) | 알겠어요 | [알게써요] |
| Formal present | 압니다 | [암니다] |
| Formal past | 알았습니다 | [아랃씀니다] |
| Formal future | 알 것입니다 | [알꺼심니다] |
| Casual present | 알아 | [아라] |
| Casual past | 알았어 | [아라써] |
| Casual future | 알 거야 | [알꺼야] |
| Want to (polite) | 알고 싶어요 | [알고 시퍼요] |
| Because / and then | 알아서 | [아라서] |
| Short negative | 안 알아요 | [안 아라요] |
| Long negative | 알지 않아요 | [알지 아나요] |
The two negative rows show how the endings attach, but in real conversation the negative of 알다 is the separate verb 모르다 (몰라요), as the next section explains.
Common Mistake
Wrong: ✗ 안 알아요 (for 'I don't know')
Correct: ✓ 몰라요
Why: Learners negate 알다 the way they negate most verbs, with 안. Korean instead uses the separate verb 모르다, so 'I don't know' is 몰라요. 안 알아요 sounds unnatural, as if you were refusing to know something.
How It Differs from Similar Words
| Word | How to tell it from 알다 |
|---|---|
| 모르다 | 알다 is to know; 모르다 is to not know, and it is the normal negative: say 몰라요 rather than negating 알다. |
| 이해하다 | 알다 is to know or be aware; 이해하다 is to understand the meaning or reason. Use 이해하다 when you grasp why, not just that. |
A Change of Classroom
Two classmates are checking where their lesson has moved.
Jisu
새 교실을 아세요?
Sae gyosireul aseyo?
Do you know the new classroom?
Alex
네, 알아요. 삼 층이에요.
Ne, arayo. Sam cheungieyo.
Yes, I do. It is on the third floor.
Jisu
알겠어요. 고마워요.
Algesseoyo. Gomawoyo.
Got it. Thank you.
The first question uses 아세요 because Jisu is asking politely about Alex's knowledge. The answer returns to 알아요: Alex does not use the honorific form for himself. The final 알겠어요 acknowledges the new information. Here it means “got it”, rather than predicting that Jisu will know something in the future.
Phrases That Go beyond Knowing a Fact
알고 싶어요 means “I want to know”. The wish attaches to 알고, so ㄹ remains. The knowledge you want can be a name, a reason or a result. Wanting information and already possessing it are different: 알아요 alone says you know it now.
알아서 하다 means to handle something yourself, using your own judgment. Literally, the pieces suggest knowing and doing; in everyday use, the phrase gives someone responsibility for deciding how to act. A parent or manager may use it when they expect the other person to work without step-by-step instructions. Tone can make it sound trusting or impatient.
아는 사이 means people know each other or are acquainted. 사이 means the relationship between people. This expression does not necessarily mean close friends. Likewise, 아는 사람 can be an acquaintance whose name you know without being someone you regularly spend time with.
Where Will You Hear 알다?
알겠습니다 is a formal acknowledgment after a workplace instruction or service request. It signals that the message has been received and understood. 알았어요 fits many ordinary polite conversations, while the casual 알았어 belongs with people you already address casually. A short, sharp reply can sound irritated even when the words are correct.
In a drama, 아세요? can ask whether someone knows a person, a place or an important fact. Listen for the missing object in the surrounding conversation. Korean often leaves it out once both speakers know what is being discussed; the verb ending alone does not tell you which kind of knowledge is meant.
Words for Finding out and Understanding
| Related word | Meaning | Useful distinction |
|---|---|---|
| 모르다 | not to know | Supplies the everyday opposite of 알다. |
| 이해하다 | to understand | Focuses on grasping an explanation or reason. |
| 알려주다 | to tell / let someone know | Passes information to another person. |
| 알아듣다 | to understand what one hears | Adds comprehension to hearing spoken words. |
For the people and places in the dialogue, see classroom vocabulary. A teacher gives information, a learner finds out, and a classmate may already know it: keeping those roles clear helps you choose among these verbs.
Mini Drill: Keep or Drop ㄹ?
- Make 알다 formal polite in the present.
- Complete “a person I know”: ____ 사람.
- Ask politely whether someone knows: 알다 → ____?
- Give the conditional “if you know”.
Show drill answers
- 압니다. ㄹ drops before the formal ending.
- 아는 사람. ㄹ drops before 는.
- 아세요? ㄹ drops before the honorific ending.
- 알면. ㄹ remains; no extra 으 is needed.
Quick Self-Test
- Which reply naturally means “I don't know”: 몰라요 or 안 알아요?
- Does 아는 사이 necessarily mean close friends?
- After receiving directions, does 알겠어요 usually predict future knowledge?
Show answers
- 몰라요.
- No. It can mean simply being acquainted.
- No. It acknowledges the directions: “I understand” or “got it”.
Frequently Asked Questions
Why Does the ㄹ Vanish in 압니다?
The ㄹ in the stem of 알다 drops before ㄴ, ㅂ, ㅅ, so formal 압니다, honorific 아세요 and modifier 아는 all lose it.
How Do I Say 'I Understand' in a Reply?
Use 알겠어요 or 알았어요. 알겠어요 is the polite 'I understand' or 'Will do' after an instruction; 알았어요 is closer to 'Got it' or 'OK'.
How Do I Say 'I Don't Know'?
Use 몰라요 from 모르다, not 안 알아요.
Can 알다 Be Used for People?
Yes. 그 사람을 알아요 means 'I know that person', and 아는 사람 means someone you know.
Which Words Are Related to 알다?
What Should You Learn Next?
Study 모르다 next, since it supplies the negative, and then 알려주다 for telling someone.
Study 모르다 next, since it supplies the negative, and then 알려주다 for telling someone; the rule behind this page is in ㄹ-drop verbs and adjectives, and any form can be checked in the Korean verb conjugator, the full list is in the Korean verb dictionary.