How do Korean verbs conjugate?
Korean verbs are built by stripping 다 from the dictionary form to get the stem, then attaching endings. The main choice is between 아 and 어, decided by the stem's last vowel. Korean conjugation does not vary by person or number at all, which makes it far more regular than any European language — the complexity is in politeness and mood, not agreement.
Stem plus ending
Every verb ends in 다 in the dictionary. Remove it and you have the stem, which is what all endings attach to. There is no first, second or third person to track.
가다 → 가 + 요 = 가요
gada → gayo
to go → go
먹다 → 먹 + 어요 = 먹어요
meokda → meogeoyo
to eat → eat
하다 → 해요
hada → haeyo
to do → do
하다 is irregular and extremely common.
The 아/어 rule
If the stem's final vowel is ㅏ or ㅗ, use 아. Otherwise use 어. This one rule governs most of the present tense, and the contractions that follow are phonetic rather than arbitrary.
받다 → 받아요
batda → badayo
to receive
ㅏ, so 아.
먹다 → 먹어요
meokda → meogeoyo
to eat
ㅓ, so 어.
보다 → 봐요
boda → bwayo
to see
ㅗ + 아 contracts to 와.
Past and future
Past inserts 았/었 before the ending, following the same vowel rule. Future commonly uses 겠 or the 을 거예요 construction, the latter being far more frequent in speech.
먹었어요
meogeosseoyo
ate
갔어요
gasseoyo
went
가 + 았 contracts.
먹을 거예요
meogeul geoyeyo
will eat
The everyday future.
Common mistakes
먹아요
먹어요
The stem vowel is ㅓ, so the ending is 어 rather than 아.
가았어요
갔어요
가 plus 았 contracts to 갔. Korean does not leave the doubled vowel.
하어요
해요
하다 is irregular — it becomes 해, not 하어. It is the most common verb in the language, so learn it as an exception.
Frequently asked questions
Is Korean conjugation hard?
It is unfamiliar rather than hard. There is no agreement for person, number or gender, so a single form covers I, you, he and they. What takes time is the number of endings for politeness, mood and connection between clauses.
How many irregular verbs are there?
Several irregular patterns rather than a long list of one-off exceptions — ㅂ, ㄷ, ㅅ, ㄹ and ㅡ irregulars. They are systematic, so learning the pattern covers every verb in that group.
Do I need to learn 겠 for the future?
Recognise it, but 을 거예요 is what you will hear most in conversation. 겠 carries a sense of intention or conjecture and is not a plain future.