기로 하다 (decide to, plan to)

The structure of 기로 하다 is surprisingly simple. You take a verb. You strip it down to its stem. Then, you just attach 기로 하다. The word 기 turns the verb into a noun. The particle 로 acts like a direction or choice marker. Finally, 하다 means "to do." When you put it all together, you are literally saying, "I do toward the action of [Verb]." Most of the time, you will see it as 기로 했다. Why the past tense? Because the decision is already finished. You aren't deciding right now. You already made up your mind. If you use 기로 해요, it sounds more like a suggestion or a current agreement between two people.

1. 1Creating this form is as easy as making ramen. Actually, it's easier. There are no tricky batchim rules here.
2. 2Find the verb you want to use. Let's take 가다 (to go).
3. 3Remove 다 to get the stem: 가.
4. 4Add 기로 하다: 가기로 하다.
5. 5Conjugate 하다 to the past tense for a finished decision: 가기로 했어요.
6. 6It works the same for verbs with a batchim. Let's try 먹다 (to eat).
7. 7Remove 다: 먹.
8. 8Add 기로 하다: 먹기로 하다.
9. 9Conjugate: 먹기로 했어요.
10. 10Even with 하다 verbs like 공부하다, just keep the stem 공부하 and add 기로 했다. It is one of the most consistent patterns in Korean. No irregulars will jump out and scare you here! Think of it like a grammar traffic light—it's always green for the stem.

You will find 기로 하다 in three main life scenarios. First, use it for Personal Resolutions. New Year's Day is the national holiday for this grammar. "I decided to quit smoking" or "I decided to learn Korean every day." It shows you are serious. Second, use it for Group Agreements. When you and your friends finally pick a restaurant after thirty minutes of arguing, use 기로 했다. It confirms the collective choice. Third, use it for Appointments and Promises. If you agreed to meet someone at 3 PM, that is a 기로 한 appointment. It carries the weight of a promise. It’s great for job interviews too. You can say you decided to apply because you love the company. It shows intent and purpose.

Don't use 기로 하다 for things you can't control. You can't "decide" for the weather to be sunny. 내일 날씨가 맑기로 했어요 sounds like you think you are a god. Use it only for voluntary actions. Also, avoid using it for immediate, unplanned reactions. If someone asks for a favor and you say "Okay, I'll do it," use -(으)ㄹ게요. 기로 하다 implies you thought about it first. It’s not for split-second choices. Finally, don't use it with adjectives unless you are describing a change you are forcing. You don't "decide to be tall." That’s just not how biology works, unfortunately.

The most frequent slip-up is forgetting the past tense. Many people say 기로 해요 when they mean they've already made the plan. Remember, 기로 했다 is the standard for existing plans. Another mistake is mixing it up with -(으)려고 하다. While they are cousins, they aren't twins. Another one? Trying to use it with "thinking" verbs. You don't "decide to think." Just decide to act! Also, watch out for the negative. If you decided not to do something, the 안 goes before the verb or you use 지 않기로 했다. Don't put the negative on the 하다 at the end, or it sounds like you just didn't make a decision at all.

How does this differ from -(으)려고 하다? Think of -(으)려고 하다 as a "soft intention." You are thinking about doing it. You have the desire. But maybe you haven't booked the flight yet. 기로 하다 is the "hard decision." The flight is booked. The calendar is marked. It is much firmer. What about -(으)ㄹ 거예요? That is a simple future fact. "I will go." It doesn't emphasize the *act of deciding* like 기로 하다 does. If -(으)ㄹ 거예요 is a straight line, 기로 하다 is a checkmark on a list. Yes, even native speakers mess this up sometimes, so don't sweat the small stuff!