고 싶다: Express

This grammar point is incredibly well-behaved. Unlike many other Korean rules, it does not care about batchim (the bottom consonant). It does not care about irregular verbs either. You just take the verb and stick 고 싶다 onto it. It functions like an adjective once it is attached. This means you conjugate the 싶다 part just like you would conjugate 좋다 or 예쁘다. If you are talking to a friend, you say 싶어. If you are being polite, you say 싶어요. Yes, even the scariest irregular verbs follow this simple rule. It is like a grammar holiday where everything just works.

1. 1Find the verb stem. This is the verb without the 다 at the end.
2. 2Add 고 싶다 directly to that stem.
3. 3Conjugate 싶다 for your desired level of politeness.
4. 4가다 (to go) → 가 + 고 싶다 = 가고 싶다 (want to go)
5. 5먹다 (to eat) → 먹 + 고 싶다 = 먹고 싶다 (want to eat)
6. 6공부하다 (to study) → 공부하 + 고 싶다 = 공부하고 싶다 (want to study)
7. 7듣다 (to listen - irregular) → 듣 + 고 싶다 = 듣고 싶다 (want to listen)
8. 8Notice how 듣다 usually changes to 들 before vowels? Here, it stays as 듣 because 고 starts with a consonant. No stress, no mess!

You use 고 싶다 when you are the one who wants something. It is perfect for first-person statements ("I want to..."). You also use it for second-person questions ("Do you want to...?").

• Ordering Food: 저는 비빔밥을 먹고 싶어요. (I want to eat bibimbap.)
• Travel Plans: 한국에 가고 싶어요. (I want to go to Korea.)
• Asking a Friend: 뭐 하고 싶어? (What do you want to do?)
• Daily Life: 집에 가고 싶어요. (I want to go home - we've all been there!)

It feels natural in almost any conversational setting. It is polite enough for a boss but casual enough for a sibling. It is the "blue jeans" of Korean grammar—it fits everywhere.

There are two big "No-Go" zones for 고 싶다. First, do not use it for other people (3rd person). If you want to say "Minjun wants to eat," you cannot use 고 싶다. You need a different version called 고 싶어 하다. Think of it like a privacy setting. You can't truly know someone else's inner heart, so the grammar changes to show you are observing them.

Second, do not use it with adjectives. You cannot say 예쁘고 싶어요 for "I want to be pretty." Adjectives describe a state, not an action. To use this with a "state," you must first turn the adjective into a verb using -아/어지다. So, "I want to become pretty" would be 예뻐지고 싶어요. It’s a small extra step, but a very important one. If you skip it, you might sound a bit like a broken robot.

• The Third Person Trap: Saying 수진 씨가 가고 싶어요 is a classic slip-up. Always remember: if it’s not "I" or "You," use 고 싶어 해요.
• The Noun Confusion: Do not attach 고 싶다 to a noun. You can't say 커피고 싶어요 to mean "I want coffee." You must use a verb like "to drink" (마시다). So, 커피를 마시고 싶어요 is the correct way.
• Adjective Error: As mentioned, 행복하고 싶어요 is technically wrong. Use 행복해지고 싶어요 instead.
• Object Particles: Sometimes people get confused between 이/가 and 을/를. With 고 싶다, you can actually use either! 사과를 먹고 싶어요 and 사과가 먹고 싶어요 are both fine, though 을/를 is more common for the action.

How is this different from 원하다? 원하다 also means "to want," but it is used mostly with nouns in a more formal or serious way. It sounds a bit heavy for daily life. You wouldn't usually say 커피를 원해요 at a cafe; you'd say 커피 마시고 싶어요.

Also, compare it to -(으)ㄹ래요. Both express desire, but -(으)ㄹ래요 is more about your immediate intention or choice. 고 싶다 is about the feeling of wanting. If someone asks "What will you have?", you say 비빔밥 먹을래요 (I'll have bibimbap). If someone asks about your dreams, you say 우주에 가고 싶어요 (I want to go to space).