Degrees of Certainty: A Map of Korean Conjecture | Korean Grammar

English keeps its guessing machinery in the adverbs: maybe, probably, surely, no way. The verb barely moves — "he comes" becomes "he'll probably come," and you tune the confidence by swapping the adverb. Korean works the other way around. It bakes the guess into the ending, and that ending encodes two things at once: how strong the guess is and where it came from — your gut, the evidence in front of you, or a snap judgment on the spot. Pick the wrong ending and you don't just sound more or less sure; you leak the wrong stance, claiming evidence you don't have or a hunch where you meant a deduction. This page is a map. Each stop links to the page that teaches it in full.

The strength scale, weakest to strongest

Imagine you're wondering whether someone will show up. Here is the same guess, dialed from "faint hope" to "impossible to doubt," and finally to flat denial.

Ending	Rough strength	"He's coming" example
-(으)ㄹ 것 같다	weak — tentative	아마 올 것 같아요
-나 보다 / -(으)ㄴ가 보다	weak — but evidence-based	오나 봐요
-는 것 같다	moderate	오는 것 같아요
-는 모양이다 / -는 듯하다	moderate — observational	오는 모양이에요
-겠-	confident — on-the-spot	곧 오겠어요
-(으)ㄹ 것이다	confident prediction	올 거예요
-(으)ㄹ 게 분명하다 / 틀림없다	near-certain	올 게 분명해요
-(으)ㄹ 리가 없다	categorical denial	올 리가 없어요

The tentative end

At the bottom, -(으)ㄹ 것 같다 paired with 아마 ("probably") is the everyday hedge. It's soft, it's polite, and it commits you to almost nothing.

아마 그 사람도 올 것 같아요.

ama geu saramdo ol geot gatayo

I think he'll probably come too.

The middle: reading the evidence

Once you have something to point at — a crowd, a closed door, a ringing-out phone — the evidential forms take over. -나 보다 and -는 모양이다 both mean "judging from what I can see," differing mainly in register (-나 보다 colloquial, -는 모양이다 a touch more written). Their adjective partner is -(으)ㄴ가 보다.

전화를 안 받아요. 바쁜가 봐요.

jeonhwareul an badayo. bappeunga bwayo

They're not picking up. Must be busy.

사람들이 우산을 쓰고 있어요. 밖에 비가 오는 모양이에요.

saramdeuri usaneul sseugo isseoyo. bakke biga oneun moyang-ieyo

People have umbrellas up. Looks like it's raining out.

The literary sibling -는 듯하다 sits alongside these — same observational feel, more written and elevated.

The confident end

-(으)ㄹ 거예요 is a plain, fairly assured prediction. -겠- is similar in strength but different in source: it's an inference you make on the spot, the moment the evidence hits you.

하늘을 보니 곧 비가 오겠어요.

haneureul boni got biga ogesseoyo

From the look of the sky, it's about to rain.

이번 주말엔 사람이 많을 거예요.

ibeon jumaren sarami maneul geoyeyo

It'll be crowded this weekend. (a settled prediction)

Near-certain, and flat denial

At the top, -(으)ㄹ 게 분명하다 ("it's clear that…"), 틀림없다 ("there's no mistaking it"), and 확실하다 ("it's certain") leave barely any doubt. Beyond even that is the mirror-image floor: -(으)ㄹ 리가 없다 flatly denies the possibility — "there's no way."

저렇게 열심히 했으니 합격할 게 분명해요.

jeoreoke yeolsimhi haesseuni hapgyeokal ge bunmyeonghaeyo

They worked so hard — they're sure to pass.

오늘 쉬는 날이에요. 가게가 열려 있을 리가 없어요.

oneul swineun narieyo. gagega yeollyeo isseul riga eopseoyo

It's their day off. There's no way the shop's open.

그럴 리가 없어요!

geureol riga eopseoyo

No way! / That can't be right!

💡

-(으)ㄹ 리가 없다 is not just a strong "probably not" — it's a flat denial of possibility, far more absolute than 안 올 것 같아요 ("I don't think he'll come"). Reach for it only when you truly mean "there's no way," or it will sound like an overreaction. See -(으)ㄹ 리가 없다.

The other axis: where the guess comes from

Strength is only half the picture — and honestly the less tricky half. The dimension that actually decides which ending a native picks is evidential source, and it splits the field into three camps.

💡

Same certainty, different source: 것 같다 is your subjective read (gut or evidence, and it can be about yourself); -나 보다 and -는 모양이다 are external-evidence inference (never your own feelings); -겠- is an on-the-spot deduction or your own resolve. English collapses all three into "probably" — which is exactly why learners reach for the wrong one.

것 같다 — subjective, and the only one you can turn on yourself

것 같다 is the general-purpose guess. It can rest on evidence or on nothing but a feeling, and uniquely it can describe your own inner state — because it doesn't claim to be reading external evidence.

저 감기 걸린 것 같아요.

jeo gamgi geollin geot gatayo

I think I've caught a cold. (about myself — 것 같다 only)

Try to say that with -나 보다 (×감기 걸렸나 봐요, about yourself) and it sounds absurd, like deducing your own illness from clues. See the wall on that in -나 보다.

-나 보다 / -는 모양이다 — the evidence made you say it

These two point outward. You're not sharing an opinion; you're reporting what the situation forces you to conclude. That's why they can't be about your own present hunger, mood, or plans — you don't infer those.

불이 다 꺼졌네요. 다들 퇴근한 모양이에요.

buri da kkeojeonneyo. dadeul toegeunhan moyang-ieyo

The lights are all off. Seems everyone's left.

-겠- — deduced this second, or decided this second

-겠- has two faces, and both are "right now." As inference, it's the empathy you voice the instant you see someone's state:

하루 종일 서 있었어요? 정말 힘들겠다.

haru jong-il seo isseosseoyo? jeongmal himdeulgetda

You were on your feet all day? That must be exhausting.

As resolve, the same -겠- announces a decision you're making on the spot:

이 일은 제가 하겠습니다.

i ireun jega hagetseumnida

I'll take care of this. (I hereby resolve to)

Adverbs still help — they just don't do the heavy lifting

Korean does have certainty adverbs, and they pair with the endings to fine-tune the guess: 아마 (probably), 어쩌면 / 혹시 (maybe, perhaps), 분명히 (surely), 틀림없이 (without doubt), 절대 (never, absolutely). But notice they reinforce the ending rather than replace it — 아마 wants a -(으)ㄹ 것 같다 or -(으)ㄹ 거예요 under it, and 절대 demands a negative like -(으)ㄹ 리가 없다. The ending sets the frame; the adverb colours it.

어쩌면 그 사람은 안 올지도 몰라요.

eojjeomyeon geu sarameun an oljido mollayo

Maybe he won't come after all.

Common Mistakes

1. Treating all of these as one interchangeable "probably." They aren't. Swapping evidential -나 보다 for subjective 것 같다 changes whether you're reading evidence or voicing a hunch.

❌ (혼잣말로 자신에 대해) 나 피곤한가 봐.

Odd as self-talk — you don't infer your own tiredness; say 나 피곤해 / 피곤한 것 같아.

✅ 나 좀 피곤한 것 같아.

na jom pigonhan geot gata

I feel a bit tired. (subjective, about myself)

2. Using -겠- for a settled future plan of your own. As a future, -겠- is on-the-spot resolve or inference, not a diary entry. For a fixed schedule use -(으)ㄹ 거예요.

❌ 저는 다음 달에 이사하겠어요.

Odd for a settled plan — sounds like a spur-of-the-moment vow.

✅ 저는 다음 달에 이사할 거예요.

jeoneun daeum dare isahal geoyeyo

I'm moving next month.

3. Piling 아마 onto a near-certain ending. 아마 ("probably") clashes with -(으)ㄹ 게 분명하다 ("it's clear that"). Match the adverb's strength to the ending's.

❌ 아마 올 게 분명해요.

Contradictory — 'probably' undercuts 'it's certain that'.

✅ 틀림없이 올 거예요.

teurimeopsi ol geoyeyo

He'll definitely come.

4. Forgetting that 것 같다 is the safe default when you're unsure which to use. When in doubt, 것 같다 rarely sounds wrong — it's the least committal, most flexible option. Reserve the evidential and near-certain forms for when you genuinely mean them.

Where to go next

Subjective guesses → 것 같다
Evidence you can point to → -나 보다 and -는 모양이다
Literary "seems" → -는 듯하다
Confident prediction → -(으)ㄹ 거예요 and -겠-
Flat denial → -(으)ㄹ 리가 없다

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