📘 Grammar 35: How to Use ~아/어야 돼요 – Expressing Obligation in Korean

📘 How to Use ~아/어야 돼요 – Expressing Obligation in Korean

Do you want to say “I have to go,” “You must study,” or “We should be careful” in Korean?

Then you need to learn the grammar structure ~아/어야 돼요, which is used to express obligation, necessity, or duty in Korean.

This form is widely used in daily conversation and is essential for expressing what someone has to or must do.

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📌 What Does ~아/어야 돼요 Mean?

~아/어야 돼요 literally means “You have to…” or “You must…”

It comes from:

• ~아/어야 하다 = to have to do
• 되다 is a conversational alternative to 하다

Structure:

• Verb stem + 아야 돼요 (for bright vowels ㅏ, ㅗ)
• Verb stem + 어야 돼요 (for other vowels)
• 하다 → 해야 돼요

📘 Example Sentences

• 지금 가야 돼요 – I have to go now
  ji-geum ga-ya dwae-yo
• 공부해야 돼요 – I must study
  gong-bu-hae-ya dwae-yo
• 운동해야 돼요 – You need to exercise
  un-dong-hae-ya dwae-yo
• 조심해야 돼요 – We must be careful
  jo-sim-hae-ya dwae-yo

📊 Grammar Table – Obligation Forms

Verb	Form	Meaning	Romanization
가다 (to go)	가야 돼요	I have to go	ga-ya dwae-yo
먹다 (to eat)	먹어야 돼요	I must eat	meok-eo-ya dwae-yo
하다 (to do)	해야 돼요	I have to do it	hae-ya dwae-yo
읽다 (to read)	읽어야 돼요	I have to read	ilg-eo-ya dwae-yo

💡 Formal Variations

• ~아/어야 합니다 – formal, written speech
• ~아/어야 해요 – polite, neutral tone
• ~아/어야 돼요 – common, colloquial and polite

📘 Negative Obligation

To express “must not,” use ~면 안 돼요

• 여기서 담배 피우면 안 돼요 – You must not smoke here
• 거짓말하면 안 돼요 – You shouldn't lie

❗ Common Mistakes

• ❌ 공부야 돼요 → ✅ 공부해야 돼요
• ❌ 가야 되요 → ✅ 가야 돼요 (되 → 돼)
• 되다 is irregular: 되 → 돼

🧪 Mini Quiz – Test Yourself!

1. How do you say “I must study” in Korean?
   a) 공부야 돼요
   b) 공부해야 돼요
   
   Click to Show Answer

   ✅ b) 공부해야 돼요

2. Translate: “You must not be late.”
   a) 늦으면 안 돼요
   b) 늦어야 돼요
   
   Click to Show Answer

   ✅ a) 늦으면 안 돼요

3. What’s the correct polite form for “I must eat”?
   a) 먹야 돼요
   b) 먹어야 돼요
   
   Click to Show Answer

   ✅ b) 먹어야 돼요

✅ Conclusion

Now you know how to express obligation and necessity in Korean using ~아/어야 돼요.

• Use this form for “must,” “should,” or “have to” situations
• It’s polite and common in conversation
• Use ~면 안 돼요 for “must not” expressions

Practice saying:

• “I must finish this” → 이거 끝내야 돼요
• “You have to rest” → 쉬어야 돼요

📘 Coming Up Next

Next lesson: How to Use ~고 나서 – Saying After Doing Something in Korean
Learn how to say “After I ate,” “After she arrived,” and more!

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