8 Ways to Use -잖아요 in Korean: Saying "You Know That"

Quick answer: -잖아요 (-janayo) means roughly "you know…" or "…, remember?" You attach it to a verb or adjective stem to point at something the listener already knows — a shared fact, a plan you both made, an obvious truth. 오늘 일요일이잖아요 = "It's Sunday, remember."

That one idea carries the whole ending: -잖아요 is for old information, not new. If your listener doesn't know the thing yet, 잖아요 is the wrong ending (you'd want -거든요 instead). If they do know it — or should — 잖아요 is exactly right, and it makes your Korean sound a lot more like a person and less like a textbook.

The form is easy. Verb or adjective stem + 잖아요: 가다 → 가잖아요, 춥다 → 춥잖아요, 있다 → 있잖아요. Past tense: stem + 았/었잖아요 → 갔잖아요, 말했잖아요. Nouns take (이)잖아요: 친구잖아요, 일요일이잖아요. In 반말 you just drop the 요: 가잖아, 말했잖아.

Here are eight ways Koreans actually use it.

1. 있잖아요 — the soft opener

있잖아요, 제가 할 말이 있어요. — "Hey, um… I have something to tell you."

This is the most common 잖아요 in daily life, and it isn't really grammar anymore — it's a conversation opener, like English "you know what…" or "so, um…". It buys you a second and signals that something is coming. Said gently, it's warm; said fast, it's just a verbal throat-clear. In 반말 it's 있잖아, which you'll hear constantly between friends.

2. Reminding someone of a shared fact

오늘 일요일이잖아요. 은행 문 안 열어요. — "It's Sunday, remember. The bank isn't open."

This is the core use. You're not informing them that it's Sunday; you're pointing at a fact you both have and drawing the conclusion from it. To a Korean ear this feels cooperative — we both know this, so here's what follows. Without 잖아요 (오늘 일요일이에요) you'd sound like you're announcing the day of the week, which is a little odd between people who both own a calendar.

3. Giving a reason they already know about you

저 매운 거 잘 못 먹잖아요. 다른 거 시킬게요. — "I can't really eat spicy food, you know. I'll order something else."

Use this when you're explaining yourself with a fact the other person has heard before. It's the polite move: you're crediting them with already knowing you, rather than re-introducing yourself. Compare -거든요, which does the opposite job — it delivers a reason the listener has not heard. Swap them and the sentence still parses, but it lands wrong: 잖아요 to someone who doesn't know the fact feels like "you should have known."

4. 말했잖아요 — "I told you, remember?"

제가 아까 말했잖아요. — "I told you earlier, remember?"

This one has a temperature. Said softly, it's a simple reminder. Said with any edge, it's "I told you" — mildly accusing, the tone you hear in dramas right before someone sighs. With a boss or an older person, soften it to 제가 아까 말씀드렸는데요 ("I did mention it earlier…"). If you want the warm version of agreeing about something you both saw coming, the phrases in "I know, right" in Korean do that job better.

5. Past tense: -았/었잖아요

어제 비 많이 왔잖아요. 그래서 길이 엄청 막혔어요. — "It rained a lot yesterday, remember. That's why the roads were so jammed."

Past-tense 잖아요 is how you anchor a story in something you both lived through. It's extremely common in small talk — weather, traffic, a long meeting. Notice the pattern: 잖아요 sets up the shared fact, and the next sentence delivers the point. If you want more raw material for this kind of opener, see talking about the weather in Korean.

6. Stating the obvious, gently

지금 겨울이잖아요. 당연히 춥죠. — "Well, it's winter. Of course it's cold."

Here 잖아요 means "as anyone can see." It's how Koreans wave at a self-evident fact before making a point about it. Keep your tone light — the same sentence delivered flatly can read as "isn't that obvious?" The safe pairing is 잖아요 plus a friendly 죠 or a smile.

7. The warm appeal: 우리 친구잖아요

우리 친구잖아요. 그런 말 안 해도 돼요. — "We're friends. You don't have to say that."

Noun + (이)잖아요 is used to appeal to a relationship you share: 우리 가족이잖아요 ("we're family"), 우리 같은 팀이잖아요 ("we're on the same team"). This is one of the kindest uses of the ending — you're reminding someone of a bond, not a fact. It's the line that follows someone over-apologizing or refusing help.

8. 반말 -잖아 between close friends

우리 내일 영화 보기로 했잖아. — "We agreed to see a movie tomorrow, remember?"

Drop the 요 and you have the friend version, which is where you'll hear 잖아 most in dramas and variety shows. It's fast, casual and a little insistent — perfect for reminding a friend of a plan they're clearly about to forget. Just make sure you're actually in a 반말 relationship first; if you're not sure where that line is, see how to drop formality in Korean.

The one mistake to avoid

Don't use 잖아요 with new information, and go easy on it with people above you.

If your coworker has never heard that you studied in Busan, saying 제가 부산에서 공부했잖아요 sounds like you're scolding them for not remembering. New fact → -거든요 (제가 부산에서 공부했거든요). Old fact → -잖아요.

And with a boss, a teacher, or someone much older, 잖아요 can carry a faint "you ought to know this" even when you don't mean it. The safe substitute is -죠(지요), which invites agreement instead of asserting shared knowledge:

• 내일 회의 있잖아요. — "There's a meeting tomorrow, remember." (fine with a peer)
• 내일 회의 있죠? — "There's a meeting tomorrow, right?" (safe with anyone)

Same facts, very different social temperature.

FAQ

What does 잖아요 mean in Korean?

-잖아요 attaches to a verb, adjective or noun and means "you know…" or "…, remember?" It marks the sentence as information the listener already has — a shared fact, a plan, or something obvious. 비 오잖아요 means "it's raining, as you can see / as you know," not simply "it's raining."

What's the difference between -잖아요 and -거든요?

They're opposites. -거든요 introduces a reason or fact the listener does not know yet; -잖아요 points at something they already do. 저 내일 시험 있거든요 = "I have a test tomorrow (you didn't know that)." 저 내일 시험 있잖아요 = "I have a test tomorrow, remember." Picking the wrong one is the most common learner mistake with this pair.

Is 잖아요 rude?

Not by itself — it's everyday polite 해요체. But because it implies "you know this already," it can sound impatient when used with new information or with someone senior to you. With a boss or an elder, use -죠 to ask for agreement instead, and save 잖아요 for friends, close coworkers and people you talk with daily.

Practice

Write the Korean, then check.

1. Remind a friend that today is Monday, so the museum is closed. (two short sentences)
2. Your friend asks why you're not ordering 김치찌개. Explain with a fact they already know about you: you can't eat spicy food.
3. Change 우리 내일 만나잖아요 into 반말.
4. "It rained a lot yesterday, remember?" (past tense)
5. Your coworker has no idea you have a cat at home. Which ending do you use to tell them — 잖아요 or 거든요?