Why Do Koreans Add 요 to Sentences?
Written and reviewed by Jun and Jin, native Korean speakers
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After this page, you can explain why Koreans add 요 to sentences.
10-second answer
The short answer
요 (yo) is the single syllable that marks polite speech (존댓말, jondaemal) at the end of a sentence. Attach it, and a casual sentence becomes polite; drop it, and a polite sentence becomes casual (반말, banmal). It's the fastest, most visible signal of politeness level in spoken Korean.
Quick check — did that land?
1. What does adding 요 to the end of a Korean sentence do?
안녕하세요! 뭐 해요? The 요 ending makes everyday Korean sound polite.
The On/Off Switch
| Casual (반말) | Polite (+요) | Meaning |
|---|---|---|
| 가 | 가요 | go / going |
| 먹었어 | 먹었어요 | ate |
| 고마워 | 고마워요 | thanks |
| 몰라 | 몰라요 | don't know |
This is exactly the mechanism behind pairs you've already seen across this site — 고마워 vs 고마워요, 괜찮아 vs 괜찮아요 — same word, 요 flips the politeness level.
고마워 vs 고마워요 vs 감사합니다 is the clearest example of this ladder: 감사합니다 vs 고마워.
See also: 반말 vs 존댓말
Where 요 Sits in the Bigger Politeness System
요-attached sentences are the "polite" (해요체) level — the everyday default with strangers, coworkers, and most adults, as covered on the banmal vs jondaemal page. It sits BELOW the most formal level (합니다체, like 갑니다 instead of 가요) but ABOVE plain casual speech.
| Level | Example | Feel |
|---|---|---|
| Formal (합니다체) | 갑니다 | News, presentations, military |
| Polite (+요) | 가요 | Everyday default with most people |
| Casual (반말) | 가 | Close friends, younger people |
요 Also Softens Single Words
요 isn't only for full sentences — it attaches to standalone words to politely soften them too, which is why you've seen forms like 네요, 정말요, and 저도요 scattered across other pages on this site. A bare word + 요 is a quick, easy way to stay polite even in a short reply.
저도요!
Me too!
저도 ("me too") + 요 — polite short reply.
정말요?
Really?
정말 ("really") + 요 — the polite version of a casual 정말?
요 After Nouns: Short Answers, 이에요/예요 and the 아니에요 Trap
In a quick answer, 요 can sit right after a noun: asked 뭐 드릴까요? ("What can I get you?") at a café, you can simply say 아메리카노요 (amerikanoyo) — the rest of the sentence is understood (ordering coffee). In a full sentence that says what something is, though, the polite ending is 이에요 after a consonant (학생이에요) and 예요 after a vowel (저예요, "It's me") — the rule is laid out on 입니다 vs 이에요.
뭐 드릴까요? — 아메리카노요.
mwo deurilkkayo? — amerikanoyo.
What can I get you? — An Americano, please.
Noun + 요: a complete, polite answer.
아니에요.
anieyo.
No, it isn't. / Not at all.
아니- + -에요. Never 아니예요.
That last one trips up Koreans too. 아니에요 is the verb 아니다 plus the ending -에요, so the National Institute of Korean Language rules 아니예요 a misspelling, even though you'll see it everywhere online. It's worth getting right, because 아니에요 is also the most common reply to thanks — see you're welcome in Korean.
Common Mistakes
Mistake #1 — Thinking 요 alone makes something formal
요-level is POLITE, not the most formal register — 합니다체 is a separate, higher tier for very formal contexts.
Mistake #2 — Dropping 요 with people you shouldn't
Removing 요 shifts you into casual 반말 — appropriate only with close friends or people younger than you, per the banmal/jondaemal rules.
Mini Quiz
2 short questions — about 1 minute
2. Is 요-level (해요체) the MOST formal level of Korean speech?
3. What does 저도요! mean?
Part of Korean Grammar Basics — Particles, Tense, and Negation
Related Knowledge
Learn Next
Time to put 요-level politeness to work in a real situation — ordering your first Korean coffee.
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