When: ~(으)ㄹ 때 (Time Clauses)

Overview

~(으)ㄹ 때 means "when" and is used to describe the time at which something happens. It creates a time clause: "when [this happens/happened], [that happens/happened]."

Pattern	Meaning	Example
Verb + (으)ㄹ 때	When [doing verb]	갈 때 (when going)
Adjective + (으)ㄹ 때	When [being adjective]	슬플 때 (when sad)
Past + 았/었을 때	When [did/was]	어렸을 때 (when young/was young)

때 by itself means "time" -- so ~(으)ㄹ 때 literally means "the time when [something will/would happen]."

How to Form ~(으)ㄹ 때

Stem ending	Ending	Example
Vowel (no 받침)	~ㄹ 때	가다 → 갈 때, 하다 → 할 때
Consonant (받침)	~을 때	먹다 → 먹을 때, 있다 → 있을 때
ㄹ받침	~ㄹ 때 (ㄹ stays)	알다 → 알 때, 살다 → 살 때

Conjugation table

Dictionary	Stem	+ (으)ㄹ 때	Result
가다 (go)	가	가 + ㄹ 때	갈 때
오다 (come)	오	오 + ㄹ 때	올 때
하다 (do)	하	하 + ㄹ 때	할 때
먹다 (eat)	먹	먹 + 을 때	먹을 때
읽다 (read)	읽	읽 + 을 때	읽을 때
있다 (exist)	있	있 + 을 때	있을 때
없다 (not exist)	없	없 + 을 때	없을 때
좋다 (good)	좋	좋 + 을 때	좋을 때
크다 (big)	크	크 + ㄹ 때	클 때
알다 (know)	알	알 때	알 때
살다 (live)	살	살 때	살 때
슬프다 (sad)	슬프	슬프 + ㄹ 때	슬플 때

Part 1: Present/Future "When"

Use ~(으)ㄹ 때 with the base stem (no tense marker) for present or future situations.

Future events

한국에 갈 때 선물을 사 올게요. (When I go to Korea, I'll buy gifts.)
졸업할 때 뭐 할 거예요? (When you graduate, what will you do?)
집에 올 때 우유 좀 사 와. (When you come home, buy some milk.)

Habitual/recurring events

슬플 때 음악을 들어요. (When I'm sad, I listen to music.)
시간이 있을 때 운동해요. (When I have time, I exercise.)
스트레스를 받을 때 산책해요. (When I'm stressed, I take a walk.)
모를 때 물어보세요. (When you don't know, ask.)

In-progress actions

Even for actions in progress (English "while"), ~(으)ㄹ 때 is used:

밥을 먹을 때 전화가 왔어요. (When I was eating, a call came.)
공부할 때 음악을 들어요. (When I study, I listen to music.)
운전할 때 핸드폰 쓰지 마세요. (When driving, don't use your phone.)

Part 2: Past "When" (~았/었을 때)

For past situations, add past tense before 을 때:

Formation	Example
Stem + 았/었 + 을 때	갔을 때, 먹었을 때, 했을 때

Past events and states

어렸을 때 서울에 살았어요. (When I was young, I lived in Seoul.)
학생이었을 때 많이 공부했어요. (When I was a student, I studied a lot.)
처음 한국에 갔을 때 한국어를 못 했어요. (When I first went to Korea, I couldn't speak Korean.)
아팠을 때 친구가 도와줬어요. (When I was sick, my friend helped me.)

어렸을 때 -- a very common expression

어렸을 때 (when I was young / as a child) is one of the most frequently used ~(으)ㄹ 때 expressions:

어렸을 때 뭐가 되고 싶었어요? (When you were young, what did you want to be?)
어렸을 때 여기서 놀았어요. (When I was young, I played here.)

Part 3: Tense in the 때 Clause vs. Main Clause

The tense system in ~(으)ㄹ 때 clauses can be confusing. Here are the key principles:

The 때 clause uses the base stem for general/ongoing situations

Even when talking about the past overall, the 때 clause often uses the base stem (no past tense) if the action was in progress at that time:

(O) 밥을 먹을 때 전화가 왔어요. (When I was eating, a call came.)
(O) 집에 갈 때 비가 왔어요. (When I was going home, it rained.)

The 때 clause uses past tense for a completed past state

(O) 어렸을 때 서울에 살았어요. (When I was young, I lived in Seoul.)
(O) 한국에 갔을 때 김치를 많이 먹었어요. (When I went to Korea, I ate lots of kimchi.)

General rule

Situation	때 clause tense	Main clause tense
Future event	Base stem + (으)ㄹ 때	Future/present
Habitual	Base stem + (으)ㄹ 때	Present
Past in-progress	Base stem + (으)ㄹ 때	Past
Past completed state	았/었을 때	Past

Part 4: ~(으)ㄹ 때 vs. ~(으)면

Both can translate to "when" in English, but they are different:

Feature	~(으)ㄹ 때	~(으)면
Focus	Time ("at the time when")	Condition ("if/whenever")
Hypothetical	Less hypothetical	More hypothetical
Past events	O (어렸을 때)	Less natural for past events
Specific time	O	X (more about conditions)

Comparison

~(으)ㄹ 때	~(으)면
한국에 갈 때 (when I go to Korea -- specific time)	한국에 가면 (if I go to Korea -- conditional)
슬플 때 (when I'm sad -- at those times)	슬프면 (if I'm sad -- conditional)
어렸을 때 (when I was young)	(어렸으면 -- if I were young -- hypothetical, different meaning)

Common Expressions with 때

Expression	Meaning
어렸을 때	when I was young
그때	at that time
이럴 때	at times like this
그럴 때	at times like that
처음 만났을 때	when we first met
필요할 때	when needed
시간이 있을 때	when I have time

Irregular Verbs with ~(으)ㄹ 때

Type	Dictionary	+ (으)ㄹ 때
ㅂ irregular	춥다 (cold)	추울 때
ㅂ irregular	덥다 (hot)	더울 때
ㅂ irregular	어렵다 (hard)	어려울 때
ㄷ irregular	듣다 (hear)	들을 때
ㄷ irregular	걷다 (walk)	걸을 때
ㅅ irregular	짓다 (build)	지을 때

Common Mistakes

Mistake	Correction	Why
먹는 때	먹을 때	Use (으)ㄹ 때, not 는 때
갈을 때	갈 때	Vowel stems use ㄹ 때, not 을 때
좋는 때	좋을 때	Adjectives also use (으)ㄹ 때
어린 때	어렸을 때	Past state needs 았/었을 때

Summary

~(으)ㄹ 때 = "when" -- vowel stems + ㄹ 때, consonant stems + 을 때.
Use the base stem for present, future, and in-progress situations.
Use ~았/었을 때 for completed past states (어렸을 때, 갔을 때).
때 means "time" -- ~(으)ㄹ 때 literally means "the time of doing."
Different from ~(으)면 (if/conditional): ~(으)ㄹ 때 focuses on time, ~(으)면 focuses on condition.
ㅂ irregular stems change ㅂ → 우 before (으)ㄹ 때 (춥다 → 추울 때).