This is one of the few places where Swedish makes a distinction English simply lacks, and getting it right is a hallmark of genuinely good Swedish. The choice is between the reflexive possessive sin / sitt / sina and the plain possessives hans / hennes / dess / deras. English collapses both into "his / her / their," so you have no native instinct to fall back on — you have to run an actual rule. The good news is that the rule is a short, mechanical algorithm. The catch is one tricky configuration (embedded clauses) where most learners — and most competing explanations — go wrong. This page gives you the test, then drills the hard case.
The core distinction in one sentence
Use sin/sitt/sina when the possessor is the third-person subject of the same clause — it means "one's own." Use hans/hennes/deras for everything else — when the owner is someone other than the clause's subject.
The cleanest way to feel it is the canonical minimal pair, where the only difference is sin vs hans, and the meaning flips completely:
Han tvättar sin bil.
He's washing his own car. 'Sin' refers back to the subject 'han' — the car belongs to the washer himself.
Han tvättar hans bil.
He's washing his car — but someone ELSE's. 'Hans' points to a different man (mentioned earlier or known from context), not the subject. Same English 'his', completely different Swedish.
That second sentence is perfectly grammatical and means something specific: he is washing another man's car. English cannot make this distinction in one word — it needs "his own" vs "his (someone else's)." Swedish builds it into the pronoun.
Hon ringde sin mamma, sen ringde hon hennes mamma också.
She called her own mum, then she called her (= another woman's) mum too. 'Sin mamma' = the subject's own mother; 'hennes mamma' = a different woman's mother.
The algorithm: three questions
To choose, run the possessor through three tests. If the answer to all three is yes, use sin/sitt/sina. If any answer is no, use hans/hennes/dess/deras.
- Is the possessor third person? (han, hon, den, det, de — he, she, it, they). Sin only exists for the third person. For jag, du, vi, ni there is no reflexive-possessive choice to make: you use min, din, vår, er regardless. So sin is never in play for "I", "you", "we".
- Is the possessor the subject of the clause? Sin reflects back to the subject. If the owner is an object, or sits inside a prepositional phrase, or is not the subject, sin is impossible.
- Is the owned thing in the same clause as that subject? Sin is bound within its own clause. If the noun is in a different clause from the subject it refers to, sin usually cannot reach across.
De älskar sina barn och sitt hus.
They love their (own) children and their (own) house. Possessor 'de' is 3rd person (yes), the subject (yes), same clause (yes) → sin: 'sina barn', 'sitt hus'.
Agreement of sin/sitt/sina. Once you have chosen the reflexive, it agrees with the owned noun (not the owner), exactly like min/mitt/mina: sin for en-words, sitt (double t) for ett-words, sina for plurals.
| Owned noun | Reflexive form | Example |
|---|---|---|
| en-word (singular) | sin | sin bil (one's own car) |
| ett-word (singular) | sitt | sitt hus (one's own house) |
| plural | sina | sina vänner (one's own friends) |
The subject constraint: sin can never BE the subject
A direct consequence of test 2 is a hard ban that trips up nearly everyone: sin/sitt/sina can never appear inside the subject of a clause. Since sin must refer back to the subject, it cannot be part of the subject — there would be nothing for it to point back to yet. So a sentence that starts with "His brother…" can never start with sin bror; it must be hans bror.
Hans bror är snäll.
His brother is kind. The possessor sits inside the SUBJECT ('his brother' is the subject), so 'sin' is impossible — it must be 'hans'. 'Sin bror är snäll' is simply ungrammatical.
Sin bror är snäll. — FEL. Sina föräldrar är stränga. — FEL.
'Sin/Sina' as (part of) the subject is always wrong: say 'Hans bror är snäll', 'Hennes/Deras föräldrar är stränga'. Sin can never live in the subject.
The hard case: embedded clauses
This is where the real difficulty lives, and where careless explanations get it wrong. The rule "sin refers to the subject of its own clause" means that in a sentence with an embedded clause, sin points to the nearest subject — the subject of the clause it actually sits in, which may not be the main-clause subject.
Across a clause boundary, use hans/hennes. When the owned noun is in a different clause from the person who owns it, sin normally can't reach across — you use hans/hennes.
Han sa att hans bror skulle komma.
He said that his brother would come. 'Hans bror' is in the embedded 'att'-clause; the owner 'han' is the subject of the MAIN clause — different clause — so 'sin' can't reach it: use 'hans'.
Compare the single-clause version, where everything is local and sin is correct:
Han hälsade på sin bror.
He visited his (own) brother. One clause, possessor = subject, owned noun in the same clause → 'sin'.
The genuinely tricky one — sin points to the NEAREST subject. Now the case competitors get wrong. In Han bad henne ta sin/hennes bok ("He asked her to take her book"), the embedded infinitival clause has its own understood subject — henne (she is the one who will take the book). Because sin binds to the nearest subject, sin here means her (the woman's) own book — she takes the book belonging to herself. Hennes would mean a third person's book.
Han bad henne ta sin bok.
He asked her to take her own book. The taker is 'henne'; she is the local subject of 'ta...', so 'sin' binds to HER — the book is hers (her own).
Han bad henne ta hennes bok.
He asked her to take her book — but a THIRD person's. 'Hennes' breaks away from the local subject 'henne', so the book belongs to neither him nor her, but to some other woman.
So the locality rule is: sin always grabs the closest clause subject, not automatically the main one. In a single-clause sentence that is the main subject; inside an embedded clause it is the embedded (often understood) subject. This clause-locality is the whole game, and it is exactly what less careful resources miss when they say flatly "sin refers to the main subject."
Common Mistakes
The deepest error is structural: English speakers have no reflexive possessive at all, so they default to hans/hennes/deras everywhere — which is wrong precisely when "one's own" is meant.
❌ Han älskar hans fru. (intending 'he loves his own wife')
Incorrect — 'hans' here means he loves some OTHER man's wife. For his own wife, use the reflexive.
✅ Han älskar sin fru.
He loves his (own) wife. Possessor = subject, same clause → sin.
❌ Sin bil är ny. (as the subject)
Incorrect — sin can never be in the subject; there's no subject yet for it to refer back to.
✅ Hans/Hennes bil är ny.
His/Her car is new. In the subject, use hans/hennes.
❌ Hon tvättar sitt bil.
Incorrect agreement — 'bil' is an en-word, so the reflexive is 'sin', not the ett-form 'sitt'.
✅ Hon tvättar sin bil.
She's washing her car. Sin agrees with the owned noun: en-word → sin, ett-word → sitt.
❌ Han tror att sin bror är hemma. (sin reaching into an embedded clause)
Incorrect — 'bror' sits in the embedded att-clause, away from the main subject 'han'; sin can't cross the boundary.
✅ Han tror att hans bror är hemma.
He thinks his brother is home. Across a clause boundary, use hans.
❌ Han bad henne hämta hennes bok. (meaning her OWN book)
Incorrect for 'her own' — 'hennes' points away from the local subject 'henne' to a third person; it does not mean her own book.
✅ Han bad henne hämta sin bok.
He asked her to fetch her own book. Sin binds to the nearest subject 'henne'.
Key Takeaways
- Use sin/sitt/sina when the possessor is the third-person subject of the same clause — it means "one's own."
- Use hans/hennes/dess/deras otherwise: when the owner is not the subject, is in a different clause, or is not third person.
- The pair Han tvättar sin bil (his own) vs Han tvättar hans bil (another man's) shows the distinction English can't draw in one word.
- Sin can never be the subject — "Sin X är…" is always wrong; use hans/hennes there.
- Sin agrees with the owned noun: sin (en), sitt (ett, double t), sina (plural) — never with the owner.
- The hard case is embedded clauses: sin binds to the nearest subject. In Han bad henne ta sin bok, sin = her own book, because the local subject of "take" is henne.
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- The Reflexive Possessive sin/sitt/sinaB1 — sin/sitt/sina means 'his/her/its/their own' and points back to the subject of the same clause: Han älskar sin fru = his OWN wife, while Han älskar hans fru = some other man's wife. It agrees with the thing owned (like min/mitt/mina), is strictly 3rd-person and subject-bound — and, the detail competitors skip, can NEVER itself be part of the subject.
- The Reflexive Pronoun sigA2 — When the object of a verb is the same person as the subject, Swedish 1st and 2nd persons just reuse the ordinary object pronoun (jag tvättar mig, du tvättar dig) — but the 3rd person has a dedicated reflexive word, sig, for he/she/it/they/one. Using honom or henne instead of sig flips the meaning to 'someone else', a mistake English's '-self' suffix makes very easy to fall into.
- Using hans/hennes Instead of sinB1 — English has no reflexive possessive, so 'his own' defaults to hans — and that single transfer error changes meaning in Swedish, not just style: Han tvättade hans bil unambiguously says he washed SOMEONE ELSE'S car. This page drills the reflexive sin/sitt/sina against hans/hennes/deras, including the subject-constraint trap (sin can never sit in the subject).
- Possessive DeterminersA1 — The words for 'my/your/his...' before a noun: min/mitt/mina, din/ditt/dina, vår/vårt/våra and sin/sitt/sina AGREE with the possessed noun's gender and number, while hans, hennes, dess, er and deras are INVARIABLE. The rule English habits keep breaking: a noun after any possessive goes BARE (min bil, never *min bilen) — no definite suffix, no front article.