The short answer
Swedish possessives agree with the thing owned, not with the owner: min bok, mitt hus, mina böcker — all "my". The forms are min/mitt/mina, din/ditt/dina, hans, hennes, hens, dess, vår/vårt/våra, er/ert/era, deras. On top of that sits sin/sitt/sina, a reflexive possessive with no English equivalent: it means the owner is the subject of the same clause. Han läser sin bok is his own book; han läser hans bok is somebody else's.
Possessive pronouns in Swedish agree with the gender and number of the noun they modify, not the gender of the possessor.
For en-words, use: min, din, sin. For ett-words, use: mitt, ditt, sitt. For plural: mina, dina, sina.
Possessive forms
| Owner | en-word | ett-word | Plural | English |
|---|---|---|---|---|
| jag | min | mitt | mina | my |
| du | din | ditt | dina | your |
| han | hans | hans | hans | his |
| hon | hennes | hennes | hennes | her |
| hen | hens | hens | hens | their (singular) |
| den/det | dess | dess | dess | its |
| vi | vår | vårt | våra | our |
| ni | er | ert | era | your (plural) |
| de | deras | deras | deras | their |
| (reflexive) | sin | sitt | sina | his/her/their own |
In a sentence
min bok (en-word)
my book
mitt hus (ett-word)
my house
mina böcker (plural)
my books
hans/hennes bok
his/her book
What learners get wrong
Han tvättar hans bil. (meaning his own car)
Say instead: Han tvättar sin bil.
Hans points away from the subject. Written this way the sentence says he is washing another man's car — grammatically correct, and not what you meant.
Sin bil är röd.
Say instead: Hans bil är röd.
Sin can never be part of the subject. It only appears in what follows the verb, referring back to the subject already named.
min hus
Say instead: mitt hus
Hus is an ett-word, so the possessive takes the ett form. The agreement is with the noun, never with the speaker.
Questions people ask
- What is the difference between sin and hans?
- Sin refers back to the subject of its own clause; hans refers to someone else. Han ringde sin mamma means he called his own mother. Han ringde hans mamma means he called another man's mother. Swedish keeps a distinction English lost, and gets it wrong far less often than learners expect.
- Can sin be used with a plural owner?
- Yes. Sin/sitt/sina agrees with the thing owned, not the owner, so de tog sina väskor (they took their own bags) is right whether one person or ten. The plural form sina is chosen because väskor is plural.
- Why is it mitt and not min for some nouns?
- Because Swedish nouns are either en-words or ett-words, and the possessive matches. Min bil (en bil), mitt hus (ett hus), mina bilar and mina hus in the plural, where the two genders merge into one form.
Sources
Usage checked against Isof, the Swedish government's language institute, and Svenska Akademien. Where usage is genuinely divided, this page says so rather than inventing a rule.