Have to/Should/ Must

Category
Basic Grammar
Premium
Keyword #
-아/어/여 되다
Lesson
18

TL;DR

  • -아/어/여 되다 means "have to" or "must" and shows obligation or necessity 📋
  • Attach it to verb stems using the same vowel harmony rules as -아/어/여요 (ㅏ/ㅗ → -아 되다, everything else → -어 되다) 🎨
  • It's slightly more formal than -아/어/여야 하다/되다 and commonly used in rules, signs, and serious situations ✨

What does -아/어/여 되다 mean? 🤔

-아/어/여 되다 expresses obligation or necessity — basically "must" or "have to" in English! 💪
It's used when something is required, either by rules, social expectations, or circumstances 📜
This pattern is a bit more formal and serious than -아/어/여야 하다 or -아/어/여야 되다 🎩

How to use it 🔧

Take the verb stem and add:
  • -아 되다 if the last vowel is ㅏ or ㅗ 🟠
  • -어 되다 for all other vowels 🟢
  • -여 되다 for 하다 verbs (which contracts to -해 되다) 🔵

Examples 🌟

가다 (to go) → 가 + 아 되다 = 가야 되다
→ 지금 가야 돼요.
(I have to go now.) 🏃
먹다 (to eat) → 먹 + 어 되다 = 먹어야 되다
→ 약을 먹어야 돼요.
(You have to take medicine.) 💊
공부하다 (to study) → 공부 + 해 되다 = 공부해야 되다
→ 오늘 공부해야 돼요.
(I have to study today.) 📚
오다 (to come) → 오 + 아 되다 = 와야 되다
→ 9시까지 와야 돼요.
(You must come by 9 o'clock.) ⏰
마시다 (to drink) → 마시 + 어 되다 = 마셔야 되다
→ 물을 많이 마셔야 돼요.
(You have to drink a lot of water.) 💧

Common forms you'll see 👀

  • 해야 돼 / 해야 돼요 — have to do (informal/polite) ✅
  • 가야 돼 / 가야 돼요 — have to go 🚶
  • 먹어야 돼 / 먹어야 돼요 — have to eat 🍽️
  • 봐야 돼 / 봐야 돼요 — have to see/watch 👁️
You'll often see these shortened in casual speech! 💬

Negative form: "don't have to" 🙅

To say you don't have to do something, use -지 않아도 되다 or 안 -아/어/여도 되다:
→ 안 가도 돼요.
(You don't have to go.) 🆓
→ 먹지 않아도 돼요.
(You don't have to eat.) 🍴

-아/어/여 되다 vs -아/어/여야 하다 🤷

Both mean "have to," but there's a subtle difference:
  • -아/어/여 되다 feels slightly more colloquial and conversational 💬
  • -아/어/여야 하다 sounds slightly more proper and formal 🎓
In everyday speech, Koreans use both interchangeably! Most people won't even notice the difference 😊

When you'll hear this 🎧

You'll encounter -아/어/여 되다 everywhere:
  • Rules and regulations 📋
  • Parental advice 👨‍👩‍👧
  • Work requirements 💼
  • Social obligations 🤝
  • Warning signs ⚠️
It's one of the most essential grammar patterns for expressing necessity! 🔑

Exceptions ⚡

There are no major exceptions to this pattern! 🎉
Just remember that vowel harmony and irregular verbs (like ㄹ irregulars, ㄷ irregulars, etc.) follow their normal rules before adding -아/어/여 되다 🌈

Quick tips 💡

Tip #1: In casual speech, people often drop the 요 ending:
  • 가야 돼 (instead of 가야 돼요) 🗣️
Tip #2: 되다 comes from the verb meaning "to become" or "to be okay," so literally this pattern means "it becomes that you must..." — but just think of it as "have to!" 🧠
Tip #3: You can use this with time expressions to show deadlines:
→ 내일까지 제출해야 돼요.
(I have to submit it by tomorrow.) 📅

You've got this! Practice using -아/어/여 되다 when talking about your daily obligations and it'll become natural super fast! 화이팅! 💪✨
 
Try the following exercise.
Fill in the blanks using -아/어/여야 하다, -아/어/여야 되다, or -(으)면 안 되다. 📝
 
  • 내일 회의에 ___. (참석하다)
    • Answer
      참석해야 해요 / 참석해야 돼요
 
 
  • 도서관에서 ___. (조용히 하다)
    • Answer
      조용히 해야 해요 / 조용히 해야 돼요
 
 
  • 여기에서 ___. (담배를 피우다)
    • Answer
      담배를 피우면 안 돼요
 
 
  • 시험 전에 열심히 ___. (공부하다)
    • Answer
      공부해야 해요 / 공부해야 돼요
 
 
  • 음식을 먹기 전에 ___. (손을 씻다)
    • Answer
      손을 씻어야 해요 / 손을 씻어야 돼요
 
 
  • 수업 시간에 핸드폰을 ___. (사용하다)
    • Answer
      사용하면 안 돼요
 
 
  • 건강을 위해 매일 ___. (운동하다)
    • Answer
      운동해야 해요 / 운동해야 돼요
 
 
  • 밤늦게 ___. (시끄럽게 하다)
    • Answer
      시끄럽게 하면 안 돼요
 
 
  • 약속 시간에 ___. (늦다)
    • Answer
      늦으면 안 돼요
 
 
  • 외출할 때 ___. (문을 잠그다)
    • Answer
      문을 잠가야 해요 / 문을 잠가야 돼요
 
Vocabulary
참석하다 - to attend
조용히 하다 - to be quiet
담배를 피우다 - to smoke
공부하다 - to study
손을 씻다 - to wash hands
사용하다 - to use
운동하다 - to exercise
시끄럽게 하다 - to be noisy
늦다 - to be late
문을 잠그다 - to lock the door

Common mistakes
  • 🚫 Don't confuse -아/어/여야 하다 (must do) with -(으)면 안 되다 (must not do) — they express opposite meanings!
  • ⚠️ Remember that -아/어/여야 하다 and -아/어/여야 되다 are interchangeable, but 하다 is slightly more formal.
  • 💡 For -(으)면 안 되다, don't forget to use -으면 with verb stems ending in consonants and -면 with vowel endings.