Danish has a possessive word, sin (and its forms sit/sine), that English simply lacks: it means "his/her/its/their own," but only when the owner is the subject of the same clause. Get it wrong and you don't just sound foreign — you can change who owns the thing. Han tog sin bog means he took his own book; Han tog hans bog means he took someone else's book. English uses "his" for both, which is exactly why this is the single most notorious error for English speakers learning Danish.
The quick answer
When the owner is third person (he, she, it, they) and is the subject of the same clause, use the reflexive possessive sin / sit / sine (it agrees with the possessed noun, not the owner). When the owner is anyone else — a different person, or even a third person who is not the subject of this clause — use hans / hendes / dens / dets / deres.
The one test to memorise:
Does the possessor equal the subject of THIS clause? Yes → sin / sit / sine No → hans / hendes / dens / dets / deres
Which form of sin? Agree with the thing owned
A crucial twist: sin/sit/sine does not agree with the owner — it agrees with the noun being possessed, exactly like min/mit/mine ("my"). So the owner's gender is irrelevant; what matters is whether the possessed noun is common-gender, neuter, or plural.
| Possessed noun | Reflexive form | Example |
|---|---|---|
| common gender (en-word) | sin | sin bil (his/her own car) |
| neuter (et-word) | sit | sit hus (his/her own house) |
| plural | sine | sine bøger (his/her own books) |
Hun elsker sin bil, sit hus og sine børn.
She loves her (own) car, her (own) house and her (own) children.
One owner — hun, a woman — but the form changes with each thing she owns: sin (common), sit (neuter), sine (plural). English has no equivalent of this agreement at all; "her" never changes shape.
The meaning-changing minimal pair
This is the case that earns sin its reputation. Look at the same sentence twice:
Han tog sin bog.
He took his (own) book — the book belongs to him.
Han tog hans bog.
He took his book — but it belongs to some other man.
In the first, the owner (han) is the subject, so sin points the possession back to him: it's his own book. In the second, hans signals that the owner is not the subject — so the book belongs to a different male person mentioned or understood from context. English "He took his book" is genuinely ambiguous; Danish forces you to say which you mean. This is why a Dane will hear Han tog hans bog and immediately picture a second man.
The same split happens with women, things, and groups:
Hun ringede til sin mor.
She called her (own) mother.
Hun ringede til hendes mor.
She called her mother — i.e. someone else's mother (a friend's, say).
The subordinate-clause rule: each clause has its own subject
The test says "the subject of THIS clause" — and that matters because a sentence can contain more than one clause, each with its own subject. Sin always reaches back to the subject of the clause it lives in, not to the subject of the main sentence.
Peter sagde, at Maria havde solgt sin cykel.
Peter said that Maria had sold her (own) bike — the bike is Maria's.
Here sin sits in the subordinate clause at Maria havde solgt sin cykel, whose subject is Maria. So the bike is Maria's, not Peter's. If you wanted the bike to be Peter's (the main-clause subject), sin would be wrong, because Peter is not the subject of the clause containing the possessive — you'd use hans:
Peter sagde, at Maria havde solgt hans cykel.
Peter said that Maria had sold his bike — the bike is Peter's.
This trips up English speakers badly, because in English "Peter said that Maria had sold his bike" leaves it open. Danish nails it down clause by clause.
Sin can never be the subject itself
A hard structural limit: sin/sit/sine can only appear inside an object, a prepositional phrase, or another non-subject position — never inside the subject of the clause. The reflexive has to point back to a subject, so it logically cannot be (part of) that subject.
❌ Sin bil er ny.
Incorrect — sin cannot sit inside the subject; there is nothing for it to refer back to.
✅ Hans bil er ny.
His car is new.
So when the possessed thing is the subject of the sentence ("his car," "her idea," "their house" doing the verb), you must use hans/hendes/deres, full stop. Sin only ever lives downstream of the subject.
Plurals and the deres question
For plural owners ("they"), the reflexive plural is deres used reflexively — but note that deres is also the non-reflexive "their." Unlike sin vs hans, the plural doesn't give you two different words; deres covers both. So the meaning-changing minimal pair largely disappears in the plural, and deres is simply read from context.
De solgte deres hus og flyttede til Aarhus.
They sold their (own) house and moved to Aarhus.
The genuine sin/hans contrast is therefore a singular third-person phenomenon: sin exists precisely to disambiguate where English "his/her" is ambiguous, and Danish only bothers doing it in the singular.
Edge case: impersonal "man"
The pronoun man ("one, you, people in general") is third-person singular and behaves as a subject, so it takes the reflexive sin:
Man skal passe på sine ting i toget.
You should look after your things on the train.
Common Mistakes
The errors below are all the same mistake wearing different hats: defaulting to hans/hendes because English "his/her" feels natural, when the owner is in fact the subject.
❌ Han kører på hans cykel hver dag.
Incorrect — the owner (han) is the subject, so it must be sin.
✅ Han kører på sin cykel hver dag.
He rides his (own) bike every day.
❌ Hun glemte hendes nøgler derhjemme.
Incorrect — hun is the subject and owns the keys → sine.
✅ Hun glemte sine nøgler derhjemme.
She forgot her (own) keys at home.
❌ Sin lejlighed ligger i centrum.
Incorrect — sin can never be (in) the subject of the clause.
✅ Hans lejlighed ligger i centrum.
His apartment is in the city centre.
❌ Barnet leger med dets bold.
Incorrect — barnet is the subject, so the reflexive is needed → sin (bold is common gender).
✅ Barnet leger med sin bold.
The child is playing with its (own) ball.
❌ Hun sagde, at Lars havde mistet sin telefon — men hun mente hendes egen.
Incorrect intent — sin here makes the phone Lars's, not hers.
✅ Hun sagde, at Lars havde mistet hendes telefon.
She said that Lars had lost her phone (it's the speaker's, not Lars's).
The cure: before every third-person "his/her/its/their," find the subject of the clause it's sitting in and ask is that the owner? If yes, reach for sin/sit/sine.
Decision table
| Question | Answer | Use | Example |
|---|---|---|---|
| Is the owner 1st/2nd person (my, your, our)? | Yes | min/din/vores etc. | Jeg tog min bog. |
| Owner is 3rd person — is the possessive inside the subject of the clause? | Yes | hans/hendes/deres (sin is impossible) | Hans bil er ny. |
| Owner is 3rd person — is the owner the SUBJECT of this clause? | Yes | sin/sit/sine (agree with the thing owned) | Han tog sin bog. |
| Owner is 3rd person but NOT the subject of this clause? | Yes | hans/hendes/dens/dets/deres | Han tog hans bog. |
| Owner is plural "they"? | — | deres (covers both readings) | De solgte deres hus. |
Key takeaways
- One test only: is the 3rd-person owner the subject of the clause containing the possessive? Yes → sin/sit/sine; no → hans/hendes/deres.
- Sin/sit/sine agree with the thing owned, not the owner (sin bil, sit hus, sine børn).
- It changes meaning: sin bog = his own; hans bog = another man's.
- Sin can never sit inside the subject — Hans bil er ny, never Sin bil....
- The contrast is singular only; for plural owners, deres does both jobs.
Now practice Danish
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Start learning Danish→Related Topics
- The Reflexive Pronoun SigA2 — Danish sig is the 3rd-person reflexive (singular and plural) used when the object refers back to the subject; learn the full mig/dig/sig/os/jer set, sig selv vs hinanden, and the inherently reflexive verbs.
- Possessive Determiners: Min, Din, Sin and MoreA1 — How Danish possessives like min, din and sin agree with the thing possessed — and which ones never change at all.
- Using Hans/Hendes Instead of SinB1 — Why Danish uses the reflexive possessive sin/sit/sine for self-owned things, and how hans/hendes/deres silently change who the owner is.
- Der vs Som: Choosing the RelativeB1 — When to use der or som as the relative pronoun — der and som both work for subjects, but only som (or nothing) can stand for an object.