A comprehensive guide to help you choose the right Korean verb and adjective endings for any situation. Use this decision-making framework to select appropriate grammar patterns.
Quick Decision Framework
1. Determine Your Main Goal
What are you trying to express?
- Statement → Basic tense endings
- Question → Question endings
- Request/Command → Imperative/request endings
- Connection → Connective endings
- Description → Modifier endings
- Reason/Cause → Causal endings
- Condition → Conditional endings
- Purpose → Purpose endings
2. Choose Politeness Level
Who are you speaking to?
- Formal/Official → -(스)ㅁ니다 forms
- Polite (Standard) → -아/어요 forms
- Casual (Friends/Family) → -아/어 forms
- Plain (Writing) → -다 forms
3. Select Time Frame
When does the action/state occur?
- Present/Current → Present tense
- Past/Completed → Past tense
- Future/Planned → Future tense
- Ongoing → Progressive forms
Decision Trees by Situation
Making Statements
GOAL: State a fact or describe something
↓
Choose time:
├─ PRESENT → -아/어요, -(스)ㅂ니다
├─ PAST → -았/었어요, -았/었습니다
└─ FUTURE → -(으)ㄹ 거예요, -겠어요
Examples:
- Present: 가요 (I go)
- Past: 갔어요 (I went)
- Future: 갈 거예요 (I will go)
Asking Questions
GOAL: Ask a question
↓
Type of question:
├─ YES/NO → -아/어요?, -(스)ㅂ니까?
├─ SUGGESTION → -(으)ㄹ까요?
├─ INTENTION → -(으)ㄹ래요?
├─ CONFIRMATION → -지요?/죠?
└─ WHY → 왜 + statement ending
Examples:
- Yes/No: 가요? (Are you going?)
- Suggestion: 갈까요? (Shall we go?)
- Intention: 갈래요? (Will you go?)
- Confirmation: 가죠? (You're going, right?)
Making Requests
GOAL: Ask someone to do something
↓
Politeness needed:
├─ VERY POLITE → -아/어 주시겠어요?
├─ POLITE → -아/어 주세요
├─ HONORIFIC → -(으)세요
├─ CASUAL → -아/어 줘
└─ COMMAND → -(으)십시오 (formal)
Examples:
- Very polite: 가 주시겠어요? (Would you please go?)
- Polite: 가 주세요 (Please go)
- Honorific: 가세요 (Please go)
- Casual: 가 줘 (Go for me)
Connecting Actions
GOAL: Connect two actions or clauses
↓
Relationship:
├─ SEQUENTIAL → -고, -아/어서
├─ SIMULTANEOUS → -(으)면서
├─ CONTRAST → -지만, -는데
├─ REASON → -아/어서, -(으)니까
└─ CONDITION → -(으)면
Examples:
- Sequential: 먹고 자요 (Eat and sleep)
- Simultaneous: 먹으면서 봐요 (Eat while watching)
- Contrast: 먹지만 안 배불러요 (I eat but I'm not full)
- Reason: 먹어서 배불러요 (I'm full because I ate)
- Condition: 먹으면 배불러요 (If I eat, I'll be full)
Expressing Ability
GOAL: Say you can or can't do something
↓
Ability type:
├─ CAN (general) → -(으)ㄹ 수 있다
├─ CAN'T (inability) → -(으)ㄹ 수 없다, 못, -지 못하다
├─ KNOW HOW → -(으)ㄹ 줄 알다
└─ DON'T KNOW HOW → -(으)ㄹ 줄 모르다
Examples:
- Can: 갈 수 있어요 (I can go)
- Can't: 갈 수 없어요, 못 가요 (I can't go)
- Know how: 갈 줄 알아요 (I know how to go)
- Don't know how: 갈 줄 몰라요 (I don't know how to go)
Expressing Desire
GOAL: Say what you want
↓
Type of desire:
├─ WANT TO (action) → -고 싶다
├─ WANT (object) → -을/를 원하다
├─ WOULD LIKE → -(으)ㄹ래요
└─ HOPE/WISH → -았/었으면 좋겠다
Examples:
- Want to: 가고 싶어요 (I want to go)
- Would like: 갈래요 (I'd like to go)
- Hope: 갔으면 좋겠어요 (I wish I had gone)
Expressing Obligation
GOAL: Say what must be done
↓
Strength of obligation:
├─ STRONG MUST → -아/어야 하다, -아/어야 되다
├─ SHOULD → -(으)ㄹ 필요가 있다
├─ HAD BETTER → -는 게 좋다
└─ PROHIBITION → -(으)면 안 되다
Examples:
- Must: 가야 해요 (I must go)
- Should: 갈 필요가 있어요 (I need to go)
- Had better: 가는 게 좋아요 (You'd better go)
- Must not: 가면 안 돼요 (You must not go)
Giving Reasons
GOAL: Explain why something happened
↓
Type of reason:
├─ NEUTRAL → -아/어서
├─ STRONG → -(으)니까
├─ EXCUSE → -느라고
└─ BECAUSE OF → -(으)ㄴ/는 바람에
Examples:
- Neutral: 바빠서 못 갔어요 (I was busy, so I couldn't go)
- Strong: 바쁘니까 못 가요 (Since I'm busy, I can't go)
- Excuse: 공부하느라고 못 갔어요 (I couldn't go because I was busy studying)
Describing Things (Modifiers)
GOAL: Describe a noun
↓
Verb or Adjective:
├─ ADJECTIVE:
│ ├─ Present/Past → -(으)ㄴ
│ └─ Future → -(으)ㄹ
│
└─ VERB:
├─ Present/Habitual → -는
├─ Past/Completed → -(으)ㄴ
└─ Future/Prospective → -(으)ㄹ
Examples:
- Adjective present: 좋은 날 (good day)
- Verb present: 가는 사람 (person who goes)
- Verb past: 간 사람 (person who went)
- Verb future: 갈 사람 (person who will go)
Situation-Based Selection Guide
At a Restaurant
Common situations:
| Situation | Ending | Example |
|---|---|---|
| Ordering | -(으)ㄹ게요 | 이걸로 할게요 |
| Asking questions | -아/어요? | 맛있어요? |
| Requesting | -아/어 주세요 | 물 좀 주세요 |
| Suggesting | -(으)ㄹ까요? | 이거 먹을까요? |
At Work/School
Professional contexts:
| Situation | Ending | Example |
|---|---|---|
| Reporting | -(스)ㅂ니다 | 보고드립니다 |
| Asking permission | -아/어도 되다 | 가도 돼요? |
| Making suggestions | -(으)ㅂ시다 | 시작합시다 |
| Requesting | -아/어 주시겠어요? | 도와주시겠어요? |
With Friends
Casual settings:
| Situation | Ending | Example |
|---|---|---|
| Statements | -아/어 | 가 |
| Questions | -아/어? | 가? |
| Suggestions | -자 | 가자 |
| Requests | -아/어 줘 | 가 줘 |
With Elders/Superiors
Respectful contexts:
| Situation | Ending | Example |
|---|---|---|
| Statements | -아/어요 | 가요 |
| Questions | -세요? | 가세요? |
| Requests | -아/어 주세요 | 가 주세요 |
| Humble actions | -아/어 드리다 | 가 드릴게요 |
Common Confusion Points
-아/어서 vs -(으)니까
When expressing reasons:
Use -아/어서:
- Neutral, objective reasons
- Past tense contexts
- After questions or imperatives
Use -(으)니까:
- Stronger, more subjective reasons
- Suggestions or commands in result clause
- Emphasizing causal relationship
Examples:
- 배고파서 먹었어요 (I was hungry, so I ate) - neutral
- 배고프니까 먹으세요 (You're hungry, so eat) - suggestion
-고 싶다 vs -(으)ㄹ래요
When expressing wanting:
Use -고 싶다:
- General desire
- Any subject (I, you, they)
- Statement of want
Use -(으)ㄹ래요:
- Immediate intention/offer
- Usually first person or questions
- Asking intention or offering
Examples:
- 가고 싶어요 (I want to go) - general desire
- 갈래요? (Do you want to go?) - asking intention
-(으)면 vs -아/어도
When expressing conditions:
Use -(으)면:
- Regular conditional "if"
- Result depends on condition
Use -아/어도:
- "Even if" concession
- Result happens regardless
Examples:
- 비가 오면 안 가요 (If it rains, I won't go) - condition matters
- 비가 와도 갈 거예요 (Even if it rains, I'll go) - doesn't matter
-는데 vs -지만
When expressing contrast:
Use -는데:
- Softer contrast
- Background information
- Can show surprise
Use -지만:
- Direct contrast
- "But" opposition
- Clear contradiction
Examples:
- 맛있는데 비싸요 (It's delicious, but expensive) - softer
- 맛있지만 비싸요 (It's delicious, but expensive) - direct contrast
Ending Combinations
Common Combinations
Many endings can combine:
| Combination | Meaning | Example |
|---|---|---|
| -(으)ㄹ 수 있다 + 겠다 | Will be able to | 갈 수 있겠어요 |
| -고 싶다 + -았/었다 | Wanted to | 가고 싶었어요 |
| -(으)ㄹ 것 같다 | Seems like will | 갈 것 같아요 |
| -아/어야 하다 + -았/었다 | Had to | 가야 했어요 |
| -(으)ㄹ 수 있다 + -았/었다 | Could/Was able to | 갈 수 있었어요 |
Advanced Combinations
| Combination | Meaning | Example |
|---|---|---|
| -아/어 주다 + -았/었으면 좋겠다 | Wish would do for me | 가 줬으면 좋겠어요 |
| -(으)ㄹ 수 있다 + -게 하다 | Enable to | 갈 수 있게 해요 |
| -고 있다 + -았/었다 | Was doing | 가고 있었어요 |
Selection Tips by Learner Level
Beginner Priority
Focus on these first:
- Basic tense: -아/어요, -았/었어요, -(으)ㄹ 거예요
- Questions: -아/어요?, -(으)ㄹ까요?
- Requests: -아/어 주세요
- Want: -고 싶다
- Can: -(으)ㄹ 수 있다
Intermediate Priority
Add these patterns:
- Connectors: -고, -아/어서, -지만
- Conditionals: -(으)면, -아/어도
- Experience: -아/어 보다
- Obligation: -아/어야 하다
- Progressive: -고 있다
Advanced Priority
Master these for fluency:
- Nuanced reasons: -(으)니까, -느라고
- Background: -는데
- Supposition: -(으)ㄴ 것 같다
- Completion: -아/어 버리다
- Complex combinations
Quick Reference Flowchart
When to Use What
TIME-RELATED:
- Now → -아/어요
- Before → -았/었어요
- Later → -(으)ㄹ 거예요
- During → -고 있다
- Habit → -곤 하다
ACTION-RELATED:
- Can do → -(으)ㄹ 수 있다
- Want to do → -고 싶다
- Must do → -아/어야 하다
- Try doing → -아/어 보다
- Finish doing → -아/어 버리다
PEOPLE-RELATED:
- For someone → -아/어 주다
- For elder/superior → -아/어 드리다
- From someone → -아/어 받다
- With someone → -랑/하고
CONNECTION-RELATED:
- And then → -고
- Because → -아/어서, -(으)니까
- But → -지만, -는데
- If → -(으)면
- When → -(으)ㄹ 때
Practice Strategy
Step-by-Step Mastery
- Learn one ending deeply before moving to next
- Practice in context with real sentences
- Compare similar patterns to understand differences
- Combine endings once you master basics
- Use in conversation to internalize
Testing Your Choice
Ask yourself:
- What's my main goal? (statement, question, request, etc.)
- Who am I talking to? (formal, polite, casual)
- When did/will it happen? (past, present, future)
- What's the relationship? (cause, contrast, sequence, etc.)
- What nuance do I want? (emphasis, softness, directness)
Common Mistakes to Avoid
Don't Mix Politeness Levels
Inconsistent: ❌ 가요. 먹었어. (polite + casual)
Consistent: ✅ 가요. 먹었어요. (both polite) ✅ 가. 먹었어. (both casual)
Don't Overuse Formal Speech
Too formal with friends: ❌ 같이 갑시다! (too formal for friends)
Appropriate: ✅ 같이 가자! (casual with friends) ✅ 같이 가요! (polite with acquaintances)
Don't Confuse Verb and Adjective Modifiers
Wrong: ❌ 가는 사람 (X - if describing permanent state) ❌ 좋는 책 (X - adjectives don't use -는)
Right: ✅ 간 사람 (person who went) ✅ 좋은 책 (good book)
Key Takeaways
- ✅ Consider context first: Situation determines ending choice
- ✅ Match politeness level: Stay consistent throughout conversation
- ✅ Start simple: Master basics before complex combinations
- ✅ Learn similar patterns together: Compare and contrast
- ✅ Practice in real situations: Context helps internalization
- ✅ Don't overthink: Native speakers choose naturally with practice
- ✅ Ask native speakers: When in doubt, ask for feedback
Use this guide as a reference when you're unsure which ending to choose. With practice, selection becomes intuitive!