Learn Hardcore Korean: oneureun keopi daesin chareul masilge. - I’ll drink tea instead of coffee today.

It’s a first-person, listener-aware promise or immediate decision: “I’ll (do it), okay?” It implies you’re deciding in response to the situation or the listener. It’s not for predictions or neutral plans; it’s for commitments or choices that consider the listener. Example context: Someone says caffeine is too strong at night → 그럼 오늘은 차를 마실게.

How is -(으)ㄹ게 different from -겠다 and -(으)ㄹ 거예요?

-(으)ㄹ게: First-person promise/decision made with the listener in mind. Natural in conversation. Example: 제가 운전할게.
-겠다: Strong intention, determination, or inference; more formal/literary. Example (determination): 이제부터 차를 마시겠다.
-(으)ㄹ 거예요: Neutral future plan/prediction. No promise nuance. Example: 오늘은 차를 마실 거예요.

Is 마실게 polite? Should I say 마실게요?

마실게 = casual (to friends/peers).
마실게요 = polite casual, appropriate with most adults you’re not close with.
More formal: 마시겠습니다 (business/formal settings).

Why is there no subject like 저는? Who is doing the action?

Korean often drops the subject when it’s clear. The ending -ㄹ게 already signals a first-person subject. You can add:

저는 오늘은 커피 대신 차를 마실게요. (adds emphasis on “I” and “today”)
제가 차를 마실게요. (emphasizes “I, not someone else”)

Why use 은 on 오늘은? What nuance does it add?

오늘은 marks today as the topic and often adds a contrastive feel: “As for today (as opposed to other days)...”. Without 은—오늘 커피 대신 차를 마실게—it sounds more neutral and less contrastive.

What does 대신 mean here, and how is it different from 말고?

A 대신 B(를/을) V = “Do B instead of A.” Example: 커피 대신 차를 마실게.
A 말고 B = “Not A but B.” Often a choice or correction, slightly more colloquial. Example: 커피 말고 차 마실게. Meaning is similar here, but 대신 is a noun meaning “substitute/alternative,” while 말고 is a connective meaning “not A but….”

Should it be 대신 or 대신에?

Both work:

커피 대신 차를 마실게.
커피 대신에 차를 마실게. 대신에 can feel a touch more explicit/formal; 대신 is very common in speech. Avoid 대신으로 in this meaning.

Do I need the object particle 를 after 차? Is 차 마실게 okay?

In casual speech, dropping 를/을 is common and 차 마실게 is fine. Using 차를 is more standard/clear, especially in writing or longer sentences where roles can get ambiguous.

What’s the literal breakdown of the sentence?

오늘-은: today + topic particle
커피: coffee
대신 (대신에): instead (of)
차-를: tea + object particle
마시-ㄹ게: drink + -(으)ㄹ게 (speaker’s promise/decision) Overall: “As for today, instead of coffee, I’ll drink tea.”

Does 차 mean “car” or “tea” here?

Here it’s tea, because 마시다 means “to drink.” Verb choice disambiguates:

차를 마시다 = drink tea
차를 타다 = ride a car

How do you pronounce the sentence naturally?

Approximate: [오느른 커피 대신 차를 마실게]

오늘은 often sounds like “오느른” due to liaison.
마실게 is “ma-sil-ge” (a soft g). A simple romanization: oneureun keopi daesin chareul masilge.

Is it 마실게 or 마실께?

Correct is 마실게. The ending is -게, not -께. Note:

-게: various endings (here, the -(으)ㄹ게 promise ending).
께: honorific particle meaning “to/for (someone esteemed)” as in 선생님께. So 마실께 is a common misspelling.