-거든요 vs -잖아요

Intermediate · TOPIK II

Both explain or give a reason at the end of a sentence. -거든요 offers information or a reason the listener doesn't know; -잖아요 reminds the listener of something they already know or should know ('…, you know').

-거든요(informal addressee-raising) An expression used to indicate the speaker's reasoning or the basis for the preceding content.-잖아요(informal addressee-raising) An expression used to check with or correct the listener on something about a certain situation.

Rules of thumb

Explaining a reason the listener doesn't know: -거든요 (아까 많이 먹었거든요 'I ate a lot earlier, you see').
Pointing to shared knowledge, seeking agreement: -잖아요 (내일 주말이잖아요 'Tomorrow's the weekend, you know').
-잖아요 can sound reproachful (제가 말했잖아요! 'I told you!'), so be careful with superiors.
-거든요 also opens a story and invites a reaction (제가 요즘 요가를 배우거든요. 그런데… 'So I've been learning yoga lately, and…').
Neither is used in questions.

Example sentences

-거든요
Why aren't you eating? — I ate a lot earlier, you see.
-잖아요
You can sleep in today. Tomorrow's the weekend, you know.
-잖아요
See? I told you to take an umbrella!
-거든요
So I've been learning yoga lately. It's harder than I thought.
-거든요
I can't meet this week — I'm going on a business trip.

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