In short

Korean has no dedicated future tense - it uses two everyday tools. -(으)ㄹ 거예요 states a settled plan (I’m going to…) or a general prediction (it’ll probably…); -겠- slots into the verb for an on-the-spot guess (that must be…) or a decisive I will. 주말에 뭐 할 거예요? / 맛있겠어요!

The rule

Step 1 - -(으)ㄹ 거예요 is three pieces you already own

It is not a new ending but the modifier form from lesson 24 plus a bound noun plus the copula from lesson 2:

Verb stem + -(으)ㄹ (future modifier) + 것 (bound noun “thing”) + 이에요 (copula)

The full written shape is -(으)ㄹ 것이에요 (geosieyo). In speech 것 shrinks to 거 and 이에요 contracts to 예요, giving the form you will actually use: -(으)ㄹ 거예요. Literally it says it is a thing that [will happen] - which is exactly why 거 keeps a space (it is a noun) and why the copula on the end can go formal (겁니다) or past (거였어요).

Note the spelling: 이에요 after the vowel of 거 becomes 예요, so it is 거예요, never *거에요.

Step 2 - Choosing -ㄹ or -을 is the modifier rule from lesson 24

The (으) is the same 받침-driven choice you already make:

• Stem ends in a vowel -> -ㄹ 거예요. 가다 -> 갈 거예요.
• Stem ends in a 받침 -> -을 거예요. 먹다 -> 먹을 거예요.
• 하다 -> 할 거예요.
• A ㄹ-stem already ends in ㄹ, so it just uses that ㄹ, no 으: 만들다 -> 만들 거예요.

Irregular stems bend here exactly as in lesson 24: 듣다 (ㄷ-irregular) -> 들을 거예요, but regular 받다 -> 받을 거예요.

Step 3 - Say it right: the 거 is tensed to [꺼]

The future -(으)ㄹ makes the following consonant tense, so although you write a plain ㄱ, you pronounce 갈 거예요 as [갈꺼예요] (gal kkeoyeyo). This is automatic and applies to every -(으)ㄹ 거예요, and to the related -(으)ㄹ 수 있어요 and -(으)ㄹ 것 같아요 you will meet later.

Step 4 - Two readings, decided by the subject

Same form, two jobs:

1. Plan / intention - with a 1st- or 2nd-person subject it is a firm plan. 저는 집에 갈 거예요. (I’m going to go home.) / 뭐 할 거예요? (What are you going to do?)
2. Prediction - with a 3rd-person subject, or with weather and things outside anyone’s control, it is a confident guess. 비가 올 거예요. (It’ll probably rain.) / 그 사람은 안 올 거예요. (He probably won’t come.)

You can state your OWN plan directly, but you can only GUESS at someone else’s - so with a 3rd-person subject 거예요 is never a promise, just a well-founded prediction.

Step 5 - The past: 거였어요

Because the tail is just the copula, you make it past on the copula: 것이었어요 -> 거였어요. 갈 거였어요 (gal geoyeosseoyo) = I was going to go (a plan that was in place earlier). The verb stem before 거 stays in its plain -(으)ㄹ form; only the copula moves.

Step 6 - -겠- goes inside the verb, with no allomorph choice

-겠- sits in the tense slot on the stem, right before the final ending - the same position as 았/었 - and it attaches to any stem unchanged, 받침 or not:

Stem + -겠- + ending -> 하겠어요, 가겠어요, 먹겠어요, 살겠어요

It carries three closely related meanings:

• Decisive will (usually 1st person). A firm I will, common in polite or service speech: 제가 하겠어요. (I’ll do it.) / 곧 시작하겠습니다. (We’ll begin shortly.)
• Immediate conjecture from present evidence. You react to something in front of you right now - a plate of food, a photo, what someone just said: 맛있겠다! (That looks delicious!) / 힘들겠어요. (That must be hard.) / 피곤하겠어요. (You must be tired.)
• Frozen politeness formulas. Memorize these whole; do not translate the 겠 literally: 알겠어요 (I understand / got it), 모르겠어요 (I don’t know), 처음 뵙겠습니다 (Nice to meet you), 잘 먹겠습니다 (said before a meal).

The spontaneous reaction 맛있겠다 is plain-style (an exclamation to yourself); its 해요체 form is 맛있겠어요. Use whichever matches your listener - do not mix the two in one breath.

Step 7 - -(으)ㄹ 거예요 vs -겠-, and a look ahead

Both point at the non-past, but they lean on different grounds: -(으)ㄹ 거예요 rests on a settled plan or a broad prediction, while -겠- rests on evidence right in front of you or a will you are voicing on the spot. Seeing a great dish, a Korean says 맛있겠어요 (fresh evidence), not 맛있을 거예요.

There is a third first-person tool, -(으)ㄹ게요 (lesson 43), for a promise you make in reaction to the moment (제가 할게요). Keep it apart from 제가 할 거예요, which reports a plan you already had.

Forms & patterns

-(으)ㄹ 거예요 - the allomorph table:

-(으)ㄹ 거예요 - copula endings on the tail (verb 가다):

-겠- - invariant marker (compare the fixed 거예요 above):

Examples

Common mistakes

• 갈거예요. (galgeoyeyo.) -> 갈 거예요. (gal geoyeyo.) - 거 is the bound noun 것, so it always takes a space before it, just like 할 수 있어요 and 갈 것 같아요.
• 먹 거예요. (meok geoyeyo.) -> 먹을 거예요. (meogeul geoyeyo.) - After a 받침 the modifier ending is -을, not a bare -ㄹ. The choice is the same 받침 rule as everywhere else.
• 이 음식 맛있을 거예요. (I eumsik masisseul geoyeyo.) -> 이 음식 맛있겠어요. (I eumsik masitgesseoyo.) - Reacting to food right in front of you is fresh evidence, so it takes on-the-spot -겠-, not the prediction 거예요.
• 제가 할 거예요. (Jega hal geoyeyo.) -> 제가 할게요. (Jega halgeyo.) - When you decide to help at that moment, use the promise ending -(으)ㄹ게요 (lesson 43); 할 거예요 reports a plan you already had.
• 갈 거에요. (gal geoeyo.) -> 갈 거예요. (gal geoyeyo.) - The copula after the vowel 거 is 예요, so the spelling is 거예요, never 거에요.

Tips

• 거 = 것, so read it as a noun. It is a thing (that will happen) explains everything at once: the obligatory space, the past 거였어요, and the formal 겁니다. Get the noun and the grammar follows.
• Your plan is confident; someone else’s is a guess. With I/you 거예요 is a real plan; with weather or a third person it is only a prediction - 비가 올 거예요 means it’ll probably rain, never a promise from the sky.
• -겠- means “I can see it now.” Reach for it the instant you have fresh input - a dish, a sigh, a photo: 맛있겠다!, 힘들겠어요, 피곤하겠어요. If your basis is a standing plan instead, use 거예요.
• Bank the frozen phrases whole. 알겠어요, 모르겠어요, 처음 뵙겠습니다, 잘 먹겠습니다 are fixed expressions - never parse the 겠 or swap it out.