The short answer
Sin, sitt and sina mean that the owner is the subject of the clause the possessive stands in. Hans, hennes and deras mean the owner is somebody else. Han tog sin bok is he took his own book. Han tog hans bok is he took another man's book. The form agrees with the thing owned and never with the owner: sin before an en-word, sitt before an ett-word, sina before a plural. The reflexive can never sit inside the subject, so it is Hans bok ligger på bordet, never Sin bok. The test: if the owner is the subject of the clause the possessive is in, use sin, sitt or sina.
Han tog sin bok. Han tog hans bok. Two different books.
Both of those sentences are correct Swedish and they describe different events. In the first, the book was his own. In the second, the book belonged to some other man. English gives you one sentence for both, he took his book, and lets the situation sort it out. Swedish makes you decide before you open your mouth, and there is no neutral form to fall back on.
The rule is short. Sin, sitt and sina point back to the subject of the clause they stand in. Hans, hennes and deras point at somebody who is not that subject. Everything else on this page follows from that one line.
This is the mistake that survives longest, and the reason is unusual. Most learner errors produce a broken sentence, so somebody eventually repairs it. This one produces a perfectly good sentence about the wrong person. Nobody stops you. You say for two years that your colleague washed a stranger's car, and the room simply files it away as slightly odd information.
It only exists in the third person. With jag, du, vi or ni there is nothing to choose, because there is no second form: Jag tog min bok can only be my own book. The choice appears around han, hon, de and any noun naming a person, which is exactly where you spend most of your day once you start talking about colleagues and neighbours.
| In Swedish | What it means | When you use it |
|---|---|---|
| Han tog sin bok. | He took his own book. | The book belongs to the man who took it. |
| Han tog hans bok. | He took another man's book. | The owner is somebody else in the situation, not the person doing the taking. |
| Hon ringde sin bror. | She called her own brother. | The brother is hers. |
| Hon ringde hennes bror. | She called another woman's brother. | Say this only when you mean it, because that is what it says. |
| Anna glömde sin telefon. | Anna forgot her own phone. | A name behaves like han and hon: it is the subject, so the reflexive points at it. |
| Anna glömde hennes telefon. | Anna forgot somebody else's phone. | The phone belongs to another woman, and Anna left it behind. |
| Jag tog min bok. | I took my book. | First person. Min covers both readings, so nothing has to be decided. |
The ending comes from the thing owned, not from the owner
Sin, sitt and sina are one word in three coats, and which coat it wears has nothing to do with who the owner is. The noun that follows decides, exactly as it does for min, mitt and mina. Sin goes in front of an en-word. Sitt goes in front of an ett-word. Sina goes in front of a plural.
So it is Han tog sin bok, because bok is an en-word. Han tog sitt pass, because pass is an ett-word. Han tog sina nycklar, because nycklar is plural. The man is the same man in all three. Only the object changed. Everything you already worked out about which nouns take en and which take ett is doing the work here for a second time.
The owner leaves no mark anywhere in the word. Hon tog sitt pass and Han tog sitt pass use the same possessive, because pass is neuter in both sentences. That is the reverse of English, where his and her track the owner and nothing else, and it is the part that keeps catching English speakers out long after the reflexive rule itself has landed. Ask what the object is. Never ask who the person is.
| In Swedish | What it means | When you use it |
|---|---|---|
| Han tog sin bok. | He took his own book. | en bok, so sin. |
| Han tog sitt pass. | He took his own passport. | ett pass, so sitt. Same man, different object. |
| Han tog sina nycklar. | He took his own keys. | Plural object, so sina. |
| Hon hämtade sitt barn. | She picked up her own child. | ett barn, so sitt, even though the mother is one person. |
| De tog sina biljetter. | They took their own tickets. | Plural owner and plural object. The -a is there for the tickets. |
| Hon glömde sitt kort. | She forgot her own card. | ett kort. The owner being female changes nothing at all. |
Sin can never be part of the subject
A book lying on the table is Hans bok ligger på bordet. Never Sin bok. The reflexive has to point back at the subject of its clause, and here the possessive is inside that subject, so there is nothing behind it to point at. Sin bok ligger på bordet is not an unusual sentence or a stylistic slip. It is not Swedish.
This holds no matter how obvious the owner is. Hennes lägenhet ligger i Solna. Deras barn går i skolan här. Hans bil står på gatan. In each one the possessive is doing subject work, so the non-reflexive form is the only option, and no Swede hears anything strange about it.
A joint subject changes nothing. Erik och hans fru bor i Malmö takes hans, because Erik och sin fru would put the reflexive back inside the subject. This is the rule most textbooks compress into half a line, and it is the one that produces the oddest learner sentences when it is missing.
Move the same book into object position and the reflexive returns at once: Han hittade sin bok på bordet. Nothing changed in the world. What changed is which part of the sentence the possessive is sitting in.
| In Swedish | What it means | When you use it |
|---|---|---|
| Hans bok ligger på bordet. | His book is on the table. | The possessive is inside the subject, so sin is impossible. |
| Hennes lägenhet ligger i Solna. | Her flat is in Solna. | Same shape, same reason. Sin lägenhet cannot start a clause. |
| Deras barn går i skolan här. | Their child goes to school here. | Subject again, so deras and not sina. |
| Erik och hans fru bor i Malmö. | Erik and his wife live in Malmö. | A joint subject is still the subject. |
| Han hittade sin bok på bordet. | He found his own book on the table. | The book is now the object, so the reflexive is available again. |
The owner can be in the sentence and still not be the subject
Han gav henne sin biljett means he gave her his own ticket. Han gav henne hennes biljett means he handed over the ticket that was already hers. The same two people are in both sentences. What decides the possessive is not who stands closest to it and not who the sentence is about. It is who the subject is, and the subject is han either way.
So a sentence can name the owner out loud and still refuse the reflexive. Jag gav honom hans nycklar: the keys are his, but the subject is jag, so sin is out of reach and hans is the only form available. Hon hjälpte honom med hans läxor works the same way. Put sina there instead and the homework travels back to hon, which is not what anybody meant.
This is where the shortcut most people teach themselves falls apart. Sin is not the Swedish for his own. Sin is the Swedish for belonging to the subject, and the two only look alike for as long as the subject happens to be the owner.
Prepositions change none of it. Han bor hos sin mamma is he lives with his own mother, because the subject is han. Han bor hos hennes mamma is he lives with the mother of a woman mentioned earlier. Look for the subject, not for the nearest noun.
| In Swedish | What it means | When you use it |
|---|---|---|
| Han gav henne sin biljett. | He gave her his own ticket. | The subject is han, so sin points back at him. |
| Han gav henne hennes biljett. | He gave her the ticket that was already hers. | The ticket belongs to henne, who is the object here, so hennes. |
| Jag gav honom hans nycklar. | I gave him his keys. | The subject is jag, so the reflexive is unavailable however clear the owner is. |
| Hon hjälpte honom med hans läxor. | She helped him with his homework. | The homework is his, and he is not the subject. |
| Han bor hos sin mamma. | He lives with his own mother. | After a preposition the rule is unchanged: the subject is han. |
| Han bor hos hennes mamma. | He lives with her mother. | The mother belongs to a woman mentioned earlier, not to him. |
Subordinate clauses, where the subject changes halfway through
One sentence can hold two subjects, and the possessive answers to the one inside its own clause. Erik sa att Anna hade glömt sin telefon means Erik said Anna had forgotten her own phone. Sin points at Anna, because Anna is the subject of the att-clause. Erik never enters the calculation.
Change one word and the phone changes hands. Erik sa att Anna hade glömt hans telefon means she had forgotten Erik's phone, or another man's. Hans is doing what it always does, pointing away from the subject of the clause it stands in, and nothing about the main clause has moved.
Then the subject rule comes back, this time inside the subordinate clause. Erik sa att hans bil var trasig is correct and Erik sa att sin bil var trasig is not, because hans bil is the subject of the att-clause. Swedish keeps the ambiguity rather than break the rule, and context decides whose car it was. Subordinate clauses already move inte in front of the verb, so it is worth knowing that they move the possessive as well.
Relative clauses run on the same mechanism. Mannen som tappade sin plånbok stod framför mig: the som-clause has a subject of its own, and sin answers to that one. When a sentence has more than one verb, find the verb nearest the possessive and work from its subject.
| In Swedish | What it means | When you use it |
|---|---|---|
| Erik sa att Anna hade glömt sin telefon. | Erik said Anna had forgotten her own phone. | Sin points at Anna, the subject of the att-clause. |
| Erik sa att Anna hade glömt hans telefon. | Erik said Anna had forgotten his phone. | The phone is not Anna's. Read in context, it is Erik's. |
| Erik sa att hans bil var trasig. | Erik said his car was broken. | Hans bil is the subject of the att-clause, so sin is impossible. |
| Hon ringde sin bror när hon kom hem. | She called her own brother when she got home. | One subject across both clauses, so there is nothing to arbitrate. |
| Mannen som tappade sin plånbok stod framför mig. | The man who dropped his wallet was standing in front of me. | The som-clause carries its own subject, and sin answers to it. |
One question, asked in the right place
Find the possessive. Find the subject of the clause it sits in, the clause and not the sentence. If the owner is that subject, write sin, sitt or sina, and take the ending from the noun that follows. If the owner is anybody else, write hans, hennes or deras. If the possessive is inside the subject, the reflexive is not on the table at all.
There is a quick way to hear whether you got it right. Read the sentence back and ask how many people it needs. He took his own book needs one man. He took that other man's book needs two. If your sentence needs a second person and you wrote sin, you have just handed the object to the wrong one.
Egen is the emphatic version and it is worth having. It agrees like an adjective, so it is sin egen bil, sitt eget rum, sina egna pengar. Han betalade med sina egna pengar means he paid out of his own pocket. Sin had already told you the money was his; egen is there to insist on it.
Take five sentences you already say about other people and check them tonight. Most learners find they have been reaching for hans and hennes by default, which means a fair share of what they said last week was about somebody who was not in the room. The grammar reference here keeps the three forms side by side while you work through them.
| In Swedish | What it means | When you use it |
|---|---|---|
| Han betalade med sina egna pengar. | He paid with his own money. | Egen adds emphasis and agrees like an adjective: egen, eget, egna. |
| Hon har sitt eget rum. | She has her own room. | ett rum, so sitt eget. |
| Man måste ta med sitt pass. | You have to bring your passport. | Man is a subject like any other, so the reflexive applies to it. |
| De sålde sitt hus. | They sold their own house. | Plural owner, but hus is an ett-word, so the form is sitt. |
Questions people ask
- What is the difference between sin and hans in Swedish?
- Sin means the owner is the subject of the clause. Hans means the owner is somebody else. Han tvättade sin bil is he washed his own car. Han tvättade hans bil is he washed another man's car. Both are correct Swedish and they describe different events, which is why the wrong one is so rarely corrected.
- When do you use sin, sitt or sina in Swedish?
- Use them whenever the owner is the third-person subject of the clause the possessive stands in. Then take the form from the noun that follows: sin before an en-word, sitt before an ett-word, sina before a plural. There is no reflexive form in the first or second person, so min, din, vår and er cover both jobs on their own.
- Why can you not say Sin bok ligger på bordet?
- Because sin has to point back at the subject of its clause, and in that sentence the possessive is inside the subject itself. The correct version is Hans bok ligger på bordet. The same applies to Hennes lägenhet ligger i Solna and Deras barn går i skolan här.
- Does sin agree with the owner or with the thing owned?
- With the thing owned, and only with it. Han tog sin bok, Han tog sitt pass, Han tog sina nycklar: one owner, three forms, decided by bok, pass and nycklar. The gender of the owner is never marked, so Hon tog sitt pass and Han tog sitt pass use the same word.
- How do you choose sin or hans in a subordinate clause?
- By the subject of that clause, not the subject of the sentence. Erik sa att Anna hade glömt sin telefon means the phone is Anna's. Erik sa att Anna hade glömt hans telefon means it is not. If the possessive is part of the subject of the att-clause, only hans is possible: Erik sa att hans bil var trasig.
- Is sin the same as sig in Swedish?
- No. Sig is a reflexive object pronoun and stands after a verb: Han rakade sig means he shaved. Sin is a possessive and always stands in front of a noun. Han tvättade sig is he washed himself, while Han tvättade sin bil is he washed his own car.
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