Korean Want, Can, Must: -고 싶다, -(으)ㄹ 수 있다, -아/어야 돼요
Say want, can, and must in Korean: -고 싶다 for wishes (가고 싶어요), -(으)ㄹ 수 있다 for ability (할 수 있어요), -아/어야 돼요 for obligation — bucket-list ready.
Published:
Written by Alvin Lim Certified Korean Language Teacher (Level 2)
Korean has a clean trio for desires, abilities, and obligations: -고 싶다 = want (한국에 가고 싶어요 — I want to go to Korea), -(으)ㄹ 수 있다 = can (운전할 수 있어요 — I can drive), and -아/어야 돼요 = must (일찍 자야 돼요 — I have to sleep early). Three endings, and your bucket list, your excuses, and your New Year resolutions all become speakable.
Words for a Korean bucket list
매운 음식 is built from 맵다 (to be spicy) — another member of the ㅂ club from Lesson 18. For now, learn 매운 음식 as one chunk: it is the question every Korean will ask you at the table.
Want, can, must — which ending goes where?
Each meaning gets its own ending, and each ending recycles an attachment pattern you already own. Want behaves like -고 있다, can follows the ㄹ/을 fork from Lesson 20, and must runs on the Lesson 6 vowel rule.
매운 음식을 먹고 싶어요 = I want to eat spicy food. 한국에 꼭 가고 싶어요 = I really want to go to Korea. Third person flips to -고 싶어 하다: 친구는 서울에 가고 싶어 해요 = my friend wants to go to Seoul.
No vowel-matching, ever — 가고 싶어요, 먹고 싶어요, 하고 싶어요. K-drama bonus: 보고 싶어요, literally “I want to see you,” is THE Korean way to say “I miss you.” You have now decoded roughly half of all ballad lyrics.
Vowel stem: 운전하다 → 운전할 수 있어요 = I can drive. Consonant stem: 먹다 → 먹을 수 있어요 = I can eat (it). Swap in 없다 for cannot: 지금은 갈 수 없어요 = I cannot go right now.
The ㄹ/을 choice is exactly the one you made for 갈 거예요 and 먹을 거예요 last lesson — same fork, new destination. And yes, 못 from Lesson 14 still works: 운전 못 해요 and 운전할 수 없어요 land in the same place, one short and casual, one fuller and neutral.
가다 → 가야 돼요 = I have to go. 일찍 자다 → 일찍 자야 돼요 = I must sleep early. 연습하다 → 연습해야 돼요 = I have to practice. (해야 하다 = same meaning, a notch more formal.)
The 아/어 fork is the trusty Lesson 6 vowel rule one more time: ㅏ/ㅗ stems take 아야 (자야 돼요), the rest take 어야 (먹어야 돼요), 하다 becomes 해야. Three endings, three reused patterns, zero new mechanics.
Your resolutions, in Korean
New year or new semester, the trio covers the whole genre of self-promises:
언젠가 한국에서 혼자 여행하고 싶어요 — someday I want to travel alone in Korea (want). 이제 한국어로 주문할 수 있어요 — I can order in Korean now (can — 이제 = now, finally). 그래서 매일 단어를 연습해야 돼요 — so I have to practice vocabulary every day (must).
Notice how naturally they chain: a wish sets the goal, an ability marks the progress, an obligation books the work. That is a complete motivational speech in three endings.
New year, new goals
All three endings fire in four bubbles — a wish, a limitation, an obligation, an offer. When desire, ability, and duty each have their own grammar slot, you stop translating word-by-word and start thinking in Korean shapes.
FAQ
How do I say someone ELSE wants something? For yourself, or when asking the listener, use -고 싶다: 가고 싶어요. For a third person, Korean switches to -고 싶어 하다: 동생은 한국에 가고 싶어 해요 = my younger sibling wants to go to Korea. It is a small swap, but native ears notice it immediately.
Is 못 해요 the same as 할 수 없어요? They overlap almost completely — both mean “can’t.” 못 (the Lesson 14 negation) is shorter and very spoken: 운전 못 해요. -(으)ㄹ 수 없어요 is a touch fuller and more neutral, and it mirrors the positive 할 수 있어요. At this level, treat them as interchangeable.
Is -아/어야 돼요 different from -아/어야 해요? Same meaning, both used daily. 돼요 leans conversational; 해요 sounds slightly more formal or written, and in 합니다-style settings you will hear 해야 합니다. A good default: say 야 돼요 when chatting, write 야 해요 in polished text.
Next: making suggestions in Korean. Previous: future plans with -(으)ㄹ 거예요. Full path: curriculum hub.