In short

도 (too, also, even), 만 (only) and 밖에 (nothing but) attach to a noun with no space and add focus to it. The rule you must not forget: they push out 이/가, 은/는 and 을/를, but they stack after 에, 에서 and 한테 - and 밖에 always needs a negative predicate (안, 못, 없다, 모르다).

The rule

Step 1 - One shape, no allomorphs

Unlike 이/가 or 을/를, these three never change form. 도 is always 도, 만 is always 만, 밖에 is always 밖에, after a vowel and after a 받침 alike: 저도 (jeodo), 책도 (chaekdo), 물만 (mulman), 하나만 (hanaman), 물밖에 (mulbakke). That is the easy half of the lesson.

Step 2 - 도 = too, also, even

Noun + 도. It says “this one as well as the other one.”

• 저도 학생이에요. (Jeodo haksaengieyo.) - I am a student too.
• 김치도 좋아해요. (Gimchido joahaeyo.) - I like kimchi too.

Repeat it on two nouns and you get both … and:

• 커피도 차도 좋아해요. (Keopido chado joahaeyo.) - I like both coffee and tea.

With something unexpected, the same 도 means even:

• 아이도 알아요. (Aido arayo.) - Even a child knows it.

Step 3 - 만 = only, just

Noun + 만. It shuts everything else out, neutrally - no complaint attached.

• 저는 물만 마셔요. (Jeoneun mulman masyeoyo.) - I drink only water.
• 공부만 해요. (Gongbuman haeyo.) - [He] does nothing but study.

Step 4 - The stacking rule (the real content of this lesson)

Korean particles come in two groups, and the focus particles treat them differently.

Group A - replaced. The subject 이/가, the topic 은/는 and the object 을/를 disappear. You write the noun, then 도/만/밖에, and nothing else:

• 저는 + 도 -> 저도 (never *저는도)
• 김치를 + 도 -> 김치도 (never *김치를도)

도 never lets the case marker back in. 만 is the one form to watch: the case marker can never come before it, but in careful or emphatic style it can follow it (저만이 왔어요, Jeomani wasseoyo; 그것만을 원해요, Geugeonmaneul wonhaeyo). At A1 the bare 저만 is what you want.

Group B - kept. The place and role particles 에, 에서, 한테/에게, (으)로 stay, and the focus particle comes after them:

• 집에 + 도 -> 집에도 (jibedo, at home too)
• 도서관에서 + 만 -> 도서관에서만 (doseogwaneseoman, only at the library)
• 친구한테 + 밖에 -> 친구한테밖에 (chinguhantebakke, to nobody but my friend)

The order is fixed: Noun + place particle + 도/만/밖에. *집도에서 is wrong.

Step 5 - 밖에 = nothing but, and it demands a negative

Noun + 밖에 + negative predicate. This is not a stylistic preference - a positive verb after 밖에 is simply ungrammatical. The negative can be 없다, 안, 못, -지 않다 or 모르다:

• 물밖에 없어요. (Mulbakke eopseoyo.) - There is nothing but water.
• 저밖에 안 왔어요. (Jeobakke an wasseoyo.) - Nobody but me came.
• 하나밖에 못 샀어요. (Hanabakke mot sasseoyo.) - I could only buy one.

English translates all of these with only, and the English only is positive - which is exactly why learners drop the 안/못. Train the pair as one chunk: 밖에 … 안/못/없어요.

Step 6 - 만 vs 밖에

Both come out as only in English, but they carry different attitudes.

• 하나만 샀어요. (Hanaman sasseoyo.) - I bought just one. Neutral: one was what I wanted.
• 하나밖에 안 샀어요. (Hanabakke an sasseoyo.) - I bought only one. Loaded: one is not much, and I feel it.

So 밖에 carries a built-in and that is too few / too little. When you simply want to state a restriction, use 만.

Step 7 - 도 with a negative: 도 안, 도 못, 하나도 안

도 combines happily with negation and gives not … either:

• 저도 안 가요. (Jeodo an gayo.) - I am not going either.

Fixed and very frequent: 하나도 + negative = not … at all (literally “not even one”).

• 하나도 안 매워요. (Hanado an maewoyo.) - It is not spicy at all.
• 하나도 없어요. (Hanado eopseoyo.) - There is none at all.

The same trick makes 아무 words negative: 아무도 안 와요. (Amudo an wayo.) - Nobody is coming.

Forms & patterns

The stacking table - what gets replaced, what gets kept:

만 vs 밖에 - the same fact, two attitudes:

Which negatives license 밖에:

Examples

Common mistakes

• 저는도 학생이에요. (Jeoneundo haksaengieyo.) -> 저도 학생이에요. (Jeodo haksaengieyo.) - 도 replaces the subject 이/가, the topic 은/는 and the object 을/를 - it does not queue up behind them. The same forms hold for 만 and 밖에: 저만, 저밖에, 김치도.
• 집도에서 공부해요. (Jipdo-eseo gongbuhaeyo.) -> 집에서도 공부해요. (Jibeseodo gongbuhaeyo.) - 에/에서/한테 are kept, and the focus particle goes last. Never insert 도 in front of a place particle.
• 물밖에 있어요. (Mulbakke isseoyo.) -> 물밖에 없어요. (Mulbakke eopseoyo.) - 밖에 cannot stand with a positive predicate. If you want a positive verb, switch to 만: 물만 있어요.
• 하나밖에 샀어요. (Hanabakke sasseoyo.) -> 하나밖에 안 샀어요. (Hanabakke an sasseoyo.) - English only is positive and the 안 gets lost in translation. 밖에 and 안/못 travel together.
• 집 밖에 없어요. (Jip bakke eopseoyo.) -> 집밖에 없어요. (Jipbakke eopseoyo.) - Spacing changes the word. Written solid, 밖에 is the particle nothing but; written apart, 밖 is the noun outside, so 집 밖에 means outside the house.

Tips

• Two groups, one line to remember them: “role particles die, place particles survive.” 이/가, 은/는, 을/를 are swallowed by 도/만/밖에; 에, 에서, 한테, (으)로 stay put and take the focus particle on their back. Almost every error in this lesson is a violation of that one line.
• 밖에 is a negative-polarity item - like English anything in “I don’t have anything”. You would never say I have anything, and Korean feels the same way about 밖에 without 안/못/없다. Drill the frame ___밖에 없어요 until it is automatic.
• Pick 만 when you are neutral, 밖에 when you are disappointed. 십 분만 있어요 (Sip bunman isseoyo) is I have just ten minutes (that is enough); 십 분밖에 없어요 (Sip bunbakke eopseoyo) is I have only ten minutes (help). Native speakers hear the difference immediately.
• 하나도 does not mean “one also”. It is not a dictionary word of its own - it is 하나 + 도 - but with a negative it works as a fixed expression meaning not at all: 하나도 안 매워요, 하나도 없어요, 하나도 모르겠어요 (Hanado moreugesseoyo, I have no idea at all). Treat it as a single vocabulary item.