A/N/V-거든 grammar = if (something is true), then ~express condition in casual conversation

A/N/V-거든 grammar = if (something is true), then ~ express condition in casual conversation

Usage:
- This grammar is used to express condition in casual conversion = "if something is true, then..." 
- Only used in casual conversation

Specific usage:
- The grammar is often used in imperative form (-세요, 십이요), propositive form (읍시다), or a form with subject’s will or conjecture (-겠-, -(ㅇ)ㄹ 것이다, or -(으)려고 하다).

e.g.

집에 도착하거든 전화 꼭 하세요.

Make sure to call me when you arrive home.

방학을 하거든 배낭여행을 가겠어요. 

If I am on vacation, I'll go backpacking.

어려운 일이 생기거든 언제든지 도와줄게요.

If you have any difficulties, I will always help you.

Tense

Adjective/Verb + 거든:

크다 --> 크거든  (if it is big...)

바쁘다 --> 바쁘거든 (if you are busy...)

있다 --> 있거든 (if you have...)

피곤하다 --> 피곤하거든 (if you feel tired...)

물어보다 --> 물어보거든 ( if you ask ...)

Noun + (이)거든:

친구 --> 친구거든 (if he is a friend...)

학생 --> 학생이거든 (if you are a student...)

주부 --> 주부거든 (if she is a housewife,...)

Examples

1. 엄마, 이렇게 더운데 꼭 같이 가야 돼요?
- 가기 싫거든 안 가도 돼. 나 혼자 다녀올게.

Mom, do I really have to go with you in this heat?
- If you don’t want to go, then you don’t have to. I will go by myself.

2. 여보 이 옷 어때요? 저에게 안 어울리는 것 같지요?
- 이 옷이 마음에 안 들거든 다른 가게에 가 봅시다.

Dear, how are these clothes? Wouldn’t you agree they’re not really my style?
- If you don’t like these, then let’s go to another store.

3. 바쁜지 않거든 잠깐 만납시다.

If you are not busy, then let’s meet for a while.

4. 할 말이 있거든 오늘 일이 끝난 후에 하세요.

If you have something to say, then let me know after work today.

5. 친한 친구거든  여행을 같이 가자고 해요.

If he is a close friend, then ask him to go on the trip together.

6. 피곤하거든 오늘은 일찍 퇴근하세요.

If you are tired, then leave work early today.

7. 다른 사람들이 물어보거든 아파서 못 갔다고 전해 주세요.

If my friends ask (about me), then please tell them that I am sick so that I can’t go.

8. 비가 그치거든 바로 출발하세요.

If the rain has stopped, then please depart now.

9. 머리가 아프거든 이 약을 드셔 보세요.

If you have a headache, then drink this medicine.

10. 요즘 많이 바쁘거든 나중에 만납시다.

If you are busy recently, then let meet later.

Comparison between -거든 and -거든요.

1. 거든 : used in mid-sentence, and express a conditional statement

E.g. 한국말이 어렵거든 매일 쓰기랑 듣기랑 읽기랑 말하기를 해야 해요.

If Korean is really difficult, then you have to write, listen, read, and speak everyday.

2. 거든요 : used in sentence-final, and express a reason known only by speaker.

E.g. 왜 점심을 안 먹었어요? - 아침을 너무 많이 먹었거든요.

Why didn't you eat lunch? - Because I ate too much in the morning.