English speakers writing Danish reach for the apostrophe automatically: Peter's bil, Danmark's historie, min mor's hus. Every one of those is wrong. Danish forms the possessive (the genitive) by gluing a bare -s onto the word, with no apostrophe and no space — Peters bil, Danmarks historie, min mors hus. The apostrophe shows up in exactly one situation, which we'll pin down below. This page is short because the rule is short — but the error is so automatic for English speakers that it needs its own drill.
The root cause: the English possessive apostrophe
In English the possessive is written with an apostrophe — Peter's car, the dog's tail, Denmark's history. That apostrophe is burned into your fingers. Danish simply never adopted it for ordinary nouns. The Danish genitive is one of the most regular things in the whole language: take any noun, any name, singular or plural, definite or indefinite, and add -s. That's it.
Peters bil er ny.
Peter's car is new.
Danmarks historie er lang.
Denmark's history is long.
Min mors hus ligger ved stranden.
My mum's house is by the beach.
The genitive -s attaches to everything
Unlike English, where the apostrophe placement changes (the dog's vs the dogs'), Danish just adds s to whatever form is already there — including plurals and definite forms. The -s lands on the very end of the word, after any plural or definite ending.
| Base word | Genitive | Meaning |
|---|---|---|
| en bil (a car) | en bils | a car's |
| bilen (the car) | bilens | the car's |
| biler (cars) | bilers | cars' |
| bilerne (the cars) | bilernes | the cars' |
| børnene (the children) | børnenes | the children's |
Bilernes lys var tændt.
The cars' lights were on. (plural definite + s, still no apostrophe)
Børnenes værelse er rodet.
The children's room is messy.
Notice there is no English-style juggling of where the apostrophe goes for plurals — Danish writes bilernes for "the cars'" with a clean final s.
The one real exception: words already ending in s, x or z
Here is the single case where an apostrophe is correct, and where leaving it out is the error. When a name or word already ends in -s, -x or -z, you do not add a second s — you cannot really pronounce it — so Danish marks the genitive with a bare apostrophe instead.
Jens' bog ligger på bordet.
Jens's book is on the table.
Marx' teori om kapital.
Marx's theory of capital.
Mads' nye cykel er rød.
Mads's new bike is red.
Schweiz' beliggenhed i Alperne.
Switzerland's location in the Alps.
The logic: the genitive marker is still "-s," but since the word already ends in that sound, the apostrophe stands in for the s you'd otherwise double. This is the mirror image of the English error — here learners often forget the apostrophe (Jens bog), which is genuinely wrong because it's indistinguishable from a plain unmarked noun.
❌ Jens bog ligger på bordet.
Wrong — without the apostrophe it doesn't read as a genitive.
✅ Jens' bog ligger på bordet.
Jens's book is on the table.
The silent-s edge case: loanwords ending in -s
A handful of borrowed words end in a written -s that is pronounced [s] but where adding another s would be unpronounceable, so they too take the apostrophe — Paris' gader (the streets of Paris), jazz'ens historie is avoided in favour of jazzens, but classic -s endings like en bus still simply add -s (bussens, not bus') because there the base s is part of an ordinary word that takes the regular definite/genitive endings. The reliable test is the spelling: does the word's dictionary form end in the letter s, x or z? If yes, apostrophe; if the s you hear is added by an ending, treat it normally.
Paris' seværdigheder er berømte.
Paris's sights are famous. (name ends in s → apostrophe)
Bussens døre lukkede for sent.
The bus's doors closed too late. (bus + definite -en, then genitive -s — ordinary, no apostrophe)
Genitive vs compound: a related trap
Sometimes what looks like a possessive is actually a Danish compound noun written as one word, and then there is no genitive -s at all (or it appears as a linking -s inside the compound). Børnehave (kindergarten, literally "children-garden") is one word, not børnenes have. Don't force a genitive where Danish wants a compound — but that's a separate topic; here, just note that a free-standing "X's Y" relationship is the genitive, and a fixed single concept is usually a compound.
Husets tag er nyt.
The house's roof is new. (genitive: husets + tag)
Vi mødtes på en legeplads.
We met at a playground. (compound 'lege+plads', not a genitive)
A note on names of companies and brands
You'll see apostrophes in some Danish shop and brand names (Magasin du Nord, Irma's-style logos borrowed from English marketing). These are stylised brand spellings, not the grammar rule, and you should not generalise from them. In ordinary running text the rule above holds.
Common Mistakes
Organised by where the English apostrophe sneaks in.
On ordinary nouns
❌ Min søster's kæreste hedder Anders.
Wrong — English apostrophe on an ordinary noun.
✅ Min søsters kæreste hedder Anders.
My sister's boyfriend is called Anders.
On place names
❌ Danmark's flag er rødt og hvidt.
Wrong — no apostrophe.
✅ Danmarks flag er rødt og hvidt.
Denmark's flag is red and white.
On personal names ending in a vowel
❌ Anna's telefon ringer.
Wrong — Anna ends in a vowel, plain s only.
✅ Annas telefon ringer.
Anna's phone is ringing.
On definite plurals
❌ Naboerne's hund gør hele natten.
Wrong — apostrophe on a definite plural.
✅ Naboernes hund gør hele natten.
The neighbours' dog barks all night.
Forgetting the apostrophe after s/x/z (the opposite error)
❌ Niels nye job.
Wrong — Niels ends in s, so the genitive needs an apostrophe.
✅ Niels' nye job.
Niels's new job.
Adding an extra s after s/x/z
❌ Mads's fødselsdag er på lørdag.
Wrong — never double the s; use the apostrophe.
✅ Mads' fødselsdag er på lørdag.
Mads's birthday is on Saturday.
Key takeaway
Two clean rules cover every case:
- Ordinary word (ends in any letter except s/x/z): add -s, no apostrophe, no space. Peters, Danmarks, børnenes.
- Word ending in s, x or z: add just an apostrophe, no extra s. Jens', Marx', Schweiz'.
If you remember only one sentence, make it this: the Danish genitive is just an s — the apostrophe is the rare exception, not the rule.
Now practice Danish
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Start learning Danish→Related Topics
- The Genitive -s (No Apostrophe)A2 — Danish forms the possessive with a plain -s glued to the noun — Peters bil, byens gader — with no apostrophe except after s, x or z.
- Danish Spelling and OrthographyA1 — An overview of how written Danish works — the 29-letter alphabet ending in æ ø å, lowercase nouns, the apostrophe-free genitive, closed compounds, and the 1948 reforms — for English speakers.
- Compound Spelling: Writing Words TogetherA2 — Danish writes compounds as one solid word — rødvin, bordtennis — and splitting them (særskrivning) is a real error that changes meaning.