Present Polite -아/어요: 좋다 → 좋아요

The -아/어요 present is the workhorse of spoken Korean — the polite 해요체 ending you will use in the vast majority of everyday sentences. On an adjective it turns 좋다 into 좋아요 ("it's nice"), 작다 into 작아요 ("it's small"). There is no copula involved and nothing added for the English "is": because an adjective is a descriptive verb, 좋아요 alone is the complete sentence "it is good." This page teaches the one choice that drives the whole ending — which vowel, 아 or 어 — and the two errors English speakers reliably make.

The rule: vowel harmony on the last stem vowel

Strip -다 to get the stem, then look at the stem's final vowel:

• If it is ㅏ or ㅗ, add -아요.
• Otherwise (any other vowel), add -어요.
• If the stem ends in 하, the result is 해요 (a special contraction — see below).

That is the entire rule. It is called vowel harmony (모음조화): the bright vowels ㅏ/ㅗ pull a bright 아, everything else takes 어. The exact same rule governs action verbs, which is one more proof that adjectives conjugate like verbs — 먹다 → 먹어요 runs on identical machinery, and only the meaning (a state, not an action) is "adjective" about it.

A reference table

Notice 좋아요 is pronounced joayo, not "jot-ayo": the ㅎ batchim of 좋- disappears before the vowel (좋아 → [조아]). And 많아요 is manayo — the ㄶ cluster loses its ㅎ and the ㄴ carries over (많아 → [마나]). These are regular sound changes; the spelling keeps the stem intact (좋아요, 많아요) while the pronunciation smooths it out.

Vowel-final stems contract

If the stem already ends in a vowel, you cannot just pile -아/어 on top — the two vowels fuse. When the stem vowel is ㅏ, adding -아 gives nothing new to write, so it simply merges:

비싸다 has the stem 비싸-, ending in ㅏ. Vowel harmony wants -아요, but 싸 + 아 collapses into a single 싸, so you write 비싸요, not ×비싸아요. The same fusion gives 싸다 → 싸요 (cheap), 크다 → 커요, 예쁘다 → 예뻐요 — but the last two involve a stem-vowel ㅡ that drops, which is its own predictable pattern covered on the 으-drop page. And the very common 하- stems (조용하다, 깨끗하다) contract to 해요 (조용해요, 깨끗해요) — see the 하다 adjectives page.

It's the same as action verbs — the meaning is the only difference

It bears repeating, because it saves you from learning two systems: the -아/어요 ending on an adjective is mechanically identical to the -아/어요 on an action verb. Compare a descriptive verb and an action verb side by side:

먹다 (ㅓ → 어요) and 많다 (ㅏ → 아요) use the exact same harmony rule. The only difference is that 먹어요 reports an action ("eats") while 많아요 reports a state ("is plentiful"). Learn the ending once and it serves both classes. For the underlying harmony logic shared across all predicates, see vowel harmony -아/어.

Why English speakers get the vowel wrong

Two errors dominate, and both are worth naming so you can catch yourself.

Error 1 — picking the vowel by feel or by the first syllable. Learners often glance at the first vowel of the word, or just guess, and produce ×좋어요 or ×작어요. But harmony is decided by the last stem vowel only. In 좋- and 작- that vowel is ㅗ/ㅏ, so the ending must be 아요. The habit to build: always find the stem, then read its final vowel, then choose. In one-syllable stems the "last" vowel is the only vowel, so 좋-, 작-, 많- are all easy once you stop guessing.

Error 2 — adding the copula anyway. Because 이에요/예요 is drilled early as "is/am/are," beginners sometimes bolt it onto an adjective: ×좋이에요, ×작아요예요. But 좋아요 is already "is good" — the -아/어요 ending is doing the predicating and the politeness both. There is no slot for a copula on a descriptive verb, exactly as on the predicative-use page.

Common Mistakes

1. Choosing the harmony vowel by intuition instead of the final stem vowel.

2. Using 어요 after a ㅏ stem.

3. Appending the copula to an adjective. The -아/어요 already predicates.

4. Writing the extra vowel on a vowel-final stem. The vowels fuse.

Key Takeaways

• The 해요체 present adds -아요 after a final stem vowel ㅏ/ㅗ, -어요 otherwise; 하- contracts to 해요.
• Decide by the last stem vowel only — not the first syllable, not intuition.
• The result predicates and is polite on its own: 좋아요 = "it's nice," with no copula added.
• This is the identical ending action verbs use (먹다 → 먹어요); only the meaning (state vs action) differs.
• Vowel-final stems fuse (비싸다 → 비싸요); the ㅡ-stems (크다, 예쁘다) and 하- stems have their own pages.