Korean irregular verbs — and how to tell them from the regular ones

ㅂ ㄷ ㅅ 르 으 ㅎ. Six patterns, but the hard part is never the list — it is that 덥다 and 입다 look identical and behave differently.

The list is not the problem

Every textbook prints the six patterns. Almost none of them says the thing that actually blocks you: a final consonant does not tell you which side a verb is on. 덥다 and 입다 both end in ㅂ. One becomes 더워요, the other 입어요. Nothing in the spelling separates them.

So the goal below is not to memorise six rules — it is to install six contrasts. Everything here builds on the regular machinery in how Korean verbs are built; if that is not automatic yet, do that first.

ㅂ — becomes 우 (but not always)

The ㅂ drops and 우 takes its place, so the ending is always -워요. Almost every ㅂ-final adjective does this; ㅂ-final verbs mostly do not.

덥다 → 더워요	it's hot
춥다 → 추워요	it's cold
어렵다 → 어려워요	it's difficult
돕다 → 도와요	the exception — 돕다 and 곱다 take 오, not 우

And the regular side, all with the same batchim:

입다 → 입어요	to wear
좁다 → 좁아요	to be narrow
잡다 → 잡아요	to catch
씹다 → 씹어요	to chew

ㄷ and ㅅ — the batchim changes or leaves

Before a vowel, an irregular ㄷ turns into ㄹ and an irregular ㅅ disappears without contracting the vowels.

듣다 → 들어요	to hear
걷다 → 걸어요	to walk
묻다(묻다·질문) → 물어요	to ask
짓다 → 지어요 · 낫다 → 나아요	to build · to get better

Same batchim, regular:

받다 → 받아요	to receive
닫다 → 닫아요	to close
묻다(파묻다) → 묻어요	to bury
웃다 → 웃어요 · 씻다 → 씻어요	to laugh · to wash

묻다 is on both lists. Ask → 물어요; bury → 묻어요. Identical spelling, two verbs, two behaviours. When you meet a word like this, the meaning is what tells you the form.

르 — the ㄹ doubles

Stems ending in 르 drop the 으 and grow a second ㄹ: 모르 + 아요 → 몰ㄹ아요 → 몰라요. This one is very consistent — if a stem ends in 르, expect it.

모르다 → 몰라요	I don't know
빠르다 → 빨라요	it's fast
부르다 → 불러요	to call · to sing
따르다 → 따라요	the exception — 따르다 and 들르다 are 으 verbs, not 르 verbs

으 — not an exception at all

Every stem ending in 으 drops it before 아/어. There is no regular counterpart to contrast with, which makes this the easiest of the six. The only decision is 아 or 어, and the syllable before the 으 decides: if its vowel is ㅏ or ㅗ you get 아, otherwise 어.

바쁘다 → 바빠요	ㅏ in 바 → 아
예쁘다 → 예뻐요	ㅖ in 예 → 어
쓰다 → 써요	nothing before it → 어
크다 → 커요	nothing before it → 어

ㅎ — and the one word that isn't

ㅎ-final adjectives drop the ㅎ and the ending fuses into 애/얘. Colours and the 이렇다/그렇다/저렇다/어떻다 family are the bulk of them.

그렇다 → 그래요	like that
어떻다 → 어때요	how is it
빨갛다 → 빨개요	it's red
좋다 → 좋아요	좋다 is regular — same batchim, ordinary 아요

좋다 is worth its own line because it is one of the most frequent words in the language and it sits on the other side of the rule.

How to get them in

Drill the pairs, not the lists. Say 더워요 — 입어요 back to back until the second one stops feeling wrong. Six pairs is twenty minutes of work and it removes the hesitation permanently.

After that, hearing beats studying. These verbs are extremely common, so any spoken set will put them in front of you dozens of times — and hearing 몰라요 fifty times installs it in a way no table can.