Forming 합니다체 is mechanical: take any stem, bolt on -(스)ㅂ니다, done. 해요체 is not so tidy, and this page is about exactly why. The ending -아/어요 begins with a vowel, and when the stem also ends in a vowel, the two collide and fuse. 오 + 아요 is not 오아요 — it's 와요. 마시 + 어요 is not 마시어요 — it's 마셔요. This fusion is the single most error-prone corner of the everyday polite register, and it is worth drilling until it's automatic, because — and this is the payoff that makes the effort pay for itself — the exact same fused stems reappear in the past tense, the future, and a dozen connectives. Learn 봐요 here and you have also, for free, learned 봤어요 and 봐서.
Before the fusion, one thing must already be decided: which vowel, -아 or -어? That is vowel harmony — if the stem's last vowel is bright (ㅏ, ㅗ) take -아요, otherwise take -어요. This page assumes harmony has already chosen and focuses on what happens when the chosen vowel meets the stem.
The mechanism: a vowel can't sit next to a vowel
Korean strongly dislikes two vowels in a row across this boundary, so it resolves the clash one of a few ways: it collapses them if they're identical, glides one into a w or y, deletes a weak ㅡ, or absorbs the ending entirely. Consonant-final stems never face this — 먹 + 어요 → 먹어요 stays fully spelled, because a consonant separates the vowels. The fusion is a vowel-stem-only phenomenon.
Type 1 — identical vowels collapse
When the stem's final vowel is the same as the ending's, the two simply merge into one; the written form loses a syllable.
| Verb | Stem + ending | 해요체 | Reading |
|---|---|---|---|
| 가다 (go) | 가 + 아요 | 가요 | gayo |
| 서다 (stand / stop) | 서 + 어요 | 서요 | seoyo |
| 만나다 (meet) | 만나 + 아요 | 만나요 | mannayo |
| 건너다 (cross) | 건너 + 어요 | 건너요 | geonneoyo |
이따가 친구를 만나요.
ittaga chingureul mannayo
I'm meeting a friend later.
여기서 길을 건너요.
yeogiseo gireul geonneoyo
Cross the street here.
Type 2 — the ㅗ / ㅜ glides (와요, 봐요, 줘요)
A stem ending in ㅗ glides into a ㅘ (wa) before -아요; a stem ending in ㅜ glides into ㅝ (wo) before -어요. The rounded vowel doesn't vanish — it becomes the w at the front of the fused syllable.
| Verb | Stem + ending | 해요체 | Reading |
|---|---|---|---|
| 오다 (come) | 오 + 아요 | 와요 | wayo |
| 보다 (see) | 보 + 아요 | 봐요 | bwayo |
| 주다 (give) | 주 + 어요 | 줘요 | jwoyo |
| 배우다 (learn) | 배우 + 어요 | 배워요 | baewoyo |
지금 밖에 비가 와요.
jigeum bakke biga wayo
It's raining outside right now.
아이한테 매일 우유를 줘요.
aihante maeil uyureul jwoyo
I give the child milk every day.
저는 요즘 태권도를 배워요.
jeoneun yojeum taegwondoreul baewoyo
I'm learning taekwondo these days.
Type 3 — the ㅣ glide (마셔요, 기다려요)
A stem ending in ㅣ glides into a y before -어요, yielding a ㅕ (yeo) syllable. 마시 + 어요 becomes 마셔요; 기다리 + 어요 becomes 기다려요.
| Verb | Stem + ending | 해요체 | Reading |
|---|---|---|---|
| 마시다 (drink) | 마시 + 어요 | 마셔요 | masyeoyo |
| 기다리다 (wait) | 기다리 + 어요 | 기다려요 | gidaryeoyo |
| 다니다 (attend / commute) | 다니 + 어요 | 다녀요 | danyeoyo |
저는 아침마다 커피를 마셔요.
jeoneun achimmada keopireul masyeoyo
I drink coffee every morning.
동생을 삼십 분째 기다려요.
dongsaeng-eul samsip bunjjae gidaryeoyo
I've been waiting for my younger sibling for thirty minutes.
Type 4 — the ㅡ stem: drop it, and let harmony decide
A stem ending in the weak vowel ㅡ doesn't glide — it simply drops, and then the previous syllable's vowel decides which of -아/-어 wins. This is the one type where you have to look one syllable back.
| Verb | Why | 해요체 | Reading |
|---|---|---|---|
| 쓰다 (write / use) | ㅡ drops; no prior vowel → default -어 | 써요 | sseoyo |
| 크다 (be big) | ㅡ drops → default -어 | 커요 | keoyo |
| 바쁘다 (be busy) | ㅡ drops; prior vowel ㅏ is bright → -아 | 바빠요 | bappayo |
| 아프다 (hurt / be sick) | ㅡ drops; prior vowel ㅏ is bright → -아 | 아파요 | apayo |
| 예쁘다 (be pretty) | ㅡ drops; prior vowel ㅔ is dark → -어 | 예뻐요 | yeppeoyo |
친구한테 편지를 써요.
chinguhante pyeonjireul sseoyo
I'm writing a letter to a friend.
요즘 일이 너무 바빠요.
yojeum iri neomu bappayo
I'm so busy with work these days.
아기가 정말 예뻐요.
agiga jeongmal yeppeoyo
The baby is really pretty.
Note that 바쁘다 → 바빠요 (bright, because 바 has ㅏ) but 예쁘다 → 예뻐요 (dark, because 예 has ㅔ). The ㅡ carries no harmony of its own, so it defers to whatever vowel sits before it — and if nothing does, like in 쓰다, the dark -어 is the default.
Type 5 — ㅐ / ㅔ stems absorb the ending
A stem already ending in ㅐ or ㅔ simply swallows the -어; you can, and native writing routinely does, leave the extra syllable off.
| Verb | Stem + ending | 해요체 | Reading |
|---|---|---|---|
| 보내다 (send) | 보내 + 어요 | 보내요 | bonaeyo |
| 지내다 (get by / live) | 지내 + 어요 | 지내요 | jinaeyo |
| 세다 (be strong / count) | 세 + 어요 | 세요 | seyo |
부모님은 시골에서 잘 지내요.
bumonimeun sigoreseo jal jinaeyo
My parents are getting on well in the countryside.
매일 아침에 아이를 학교에 보내요.
maeil achime aireul hakgyoe bonaeyo
Every morning I send my child off to school.
Type 6 — 하 becomes 해
The verb 하다 ("do"), and the thousands of 하다-compounds built on it (공부하다, 사랑하다, 시작하다, 죄송하다), takes a special -여요 that never survives intact in speech — it always contracts to 해요.
요즘 한국어를 열심히 공부해요.
yojeum hangugeoreul yeolsimhi gongbuhaeyo
I'm studying Korean hard these days.
주말마다 등산을 해요.
jumalmada deungsaneul haeyo
I go hiking every weekend.
Why this page pays for itself: the 아/어 stem is everywhere
Here is the reason to overlearn these fusions rather than merely memorize the -아/어요 forms. What you are really building is the 아/어 stem — the fused shape a verb takes before the whole -아/어 family of endings. And that family is huge. The past tense is just this stem plus -ㅆ어요; several core connectives are this stem plus a suffix. So every contraction you nail here transfers directly:
| Verb | 해요체 (아/어 stem) | Past -았/었어요 | Sequence -아/어서 |
|---|---|---|---|
| 가다 | 가요 | 갔어요 (gasseoyo) | 가서 (gaseo) |
| 보다 | 봐요 | 봤어요 (bwasseoyo) | 봐서 (bwaseo) |
| 마시다 | 마셔요 | 마셨어요 (masyeosseoyo) | 마셔서 (masyeoseo) |
| 쓰다 | 써요 | 썼어요 (sseosseoyo) | 써서 (sseoseo) |
| 하다 | 해요 | 했어요 (haesseoyo) | 해서 (haeseo) |
어제 그 영화를 봤어요. 정말 재미있었어요.
eoje geu yeonghwareul bwasseoyo. jeongmal jaemiisseosseoyo
I watched that movie yesterday. It was really fun.
Common Mistakes
1. Leaving the vowels uncontracted. Two vowels can't sit side by side across this boundary; ×오아요 and ×마시어요 are non-forms.
❌ 지금 친구가 우리 집에 오아요.
Uncontracted — 오 + 아요 must fuse to 와요.
✅ 지금 친구가 우리 집에 와요.
jigeum chinguga uri jibe wayo
A friend is coming to our place right now.
2. Mis-harmonizing before you contract. Harmony picks the vowel first; a bright ㅗ stem takes -아 (봐요), a dark ㅜ stem takes -어 (줘요). ×보어요 and ×주아요 pick the wrong vowel.
❌ 잠깐만 이 가방 좀 봐 주어요.
Wrong harmony — 주 (ㅜ, dark) takes -어요, contracting to 줘요, not 주어요.
✅ 잠깐만 이 가방 좀 봐 줘요.
jamkkanman i gabang jom bwa jwoyo
Hold this bag for a second, would you.
3. Forgetting the ㅡ drop. A ㅡ stem loses the ㅡ; you cannot write it out as ×쓰어요 or ×바쁘아요.
❌ 저는 지금 이메일을 쓰어요.
The ㅡ must drop — 쓰 + 어요 → 써요.
✅ 저는 지금 이메일을 써요.
jeoneun jigeum imeireul sseoyo
I'm writing an email right now.
4. Treating 하다 as a plain vowel stem. 하 does not give ×하아요 or the bookish ×하여요 in speech — it contracts to 해요.
❌ 저녁마다 운동하아요.
하다 contracts to 해요, never 하아요.
✅ 저녁마다 운동해요.
jeonyeongmada undonghaeyo
I exercise every evening.
Key Takeaways
- -아/어요 begins with a vowel, so vowel-final stems fuse with it — the one fiddly part of 해요체.
- The six patterns: identical collapse (가요, 서요), ㅗ/ㅜ → w-glide (와요, 줘요), ㅣ → y-glide (마셔요), ㅡ drops and harmony decides (써요, 바빠요), ㅐ/ㅔ absorb (보내요), and 하 → 해요.
- With ㅡ stems, look one syllable back for harmony: 바쁘다 → 바빠요 (bright) but 예쁘다 → 예뻐요 (dark).
- These fused 아/어 stems recur everywhere — the past (봤어요), the sequence connective (봐서), and more — so mastering them here is mastering the backbone of Korean conjugation.
Now practice Korean
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning Korean→Related Topics
- 해요체: The Everyday Polite Style (-아/어요)TOPIK 1 — 해요체, the informal-polite register that carries most of adult Korean life — how vowel harmony picks -아요 vs -어요, why 요 is load-bearing, and why one -아/어요 form does the work of all four moods.
- Vowel-Stem Contractions: 가 + 아 → 가, 오 + 아 → 와, 보 + 아 → 봐TOPIK 1 — The obligatory sound-fusions that fire when a vowel-final stem meets -아/어요 — identical vowels merge, ㅗ+아 becomes ㅘ, ㅜ+어 becomes ㅝ — so the 'long' forms 가아요, 오아요, 주어요 are never written or said.
- Vowel Harmony: Choosing -아 vs -어TOPIK 1 — One rule fixes the shape of every -아/어 ending: if the stem's LAST vowel is ㅏ or ㅗ (bright), use 아; for anything else, use 어. The single memorized exception is 하다 → 해.
- Contractions in the Past (오다 → 왔어요, 마시다 → 마셨어요)TOPIK 1 — The past -았/었- attaches to the very same fused vowel-stem you already built for the present, so the contractions carry over intact — 와요 → 왔어요, 봐요 → 봤어요, 줘요 → 줬어요, 돼요 → 됐어요 — and you never conjugate the past from scratch.
- The Vowel-Contraction TableTOPIK 1 — The obligatory stem-vowel + 아/어 fusions that produce every 해요체 and past form — 가+아→가, 오+아→와, 주+어→줘, 마시+어→마셔 — plus the 되/돼 spelling test. The uncontracted forms are simply wrong.