Learn Hardcore Swedish: Hur sent vi stannar beror på mötet och på min kalender. - How late we stay depends on the meeting and on my calendar.

Because it’s an embedded (indirect) question functioning as the subject of the sentence. In Swedish, embedded questions take subordinate clause word order: subject before verb. So you get hur sent vi stannar, not hur sent stannar vi.

Direct question (main clause, inversion): Hur sent stannar vi?
Embedded/subject clause (no inversion): Hur sent vi stannar beror på …

Also note the V2 rule in the main clause: the finite verb must be in second position. The whole subject clause Hur sent vi stannar occupies position 1, so beror comes second.

What does hur sent mean, and how is it different from hur länge?

hur sent asks about time of day: how late (e.g., into the night) something goes.
hur länge asks about duration: how long (how many hours/minutes). Examples:
Hur sent vi stannar = How late we stay (e.g., till 11 pm? midnight?)
Hur länge vi stannar = How long we stay (e.g., 2 hours? 4 hours?)

Why is sent spelled with -t? Could I write sen?

sent is the adverb (also the neuter form of the adjective sen), and that’s the standard written form for “late.” In informal writing you may see sen used adverbially, but sent is the safe, standard choice here. You cannot use the plural form sena in this construction.

Why is it stannar and not stanna or stannar kvar?

stannar is the finite present tense needed in the embedded clause: hur sent vi stannar.
stanna is the infinitive; you can’t use it where a finite verb is required.
stannar kvar adds the nuance of “remain (stay put)”: Hur sent vi stannar kvar is also possible and emphasizes not leaving a place. Related alternatives:
är kvar / blir kvar: “are/remain” there. E.g., Hur länge vi blir kvar (how long we remain).
stanna uppe means “stay up (awake).” If you mean bedtime rather than staying at a venue: Hur sent vi stannar uppe.

Do I need kommer att for the future here?

No. Swedish often uses present tense for future reference when the context makes it clear: Hur sent vi stannar naturally refers to the future here. You can say Hur sent vi kommer att stanna to make the futurity explicit, but it isn’t required.

What does beror på mean, and how is it different from beroende på or hänger på?

bero på = depend on / be due to. It takes a på-phrase or på att
- clause:
  - Det beror på mötet.
  - Det beror på att mötet drar ut på tiden.
beroende på = depending on (a prepositional/participial phrase). E.g., Beroende på hur mötet går, stannar vi längre.
hänga på (colloquial) ≈ “hinge on”: Det hänger på mötet.
More formal alternative: avgöras av (be determined by).

Why is it på mötet och på min kalender? Do I have to repeat på?

Repeating på is optional here. You can say:

… beror på mötet och på min kalender (repetition; clear and common), or
… beror på mötet och min kalender (single preposition; also acceptable). Writers often repeat the preposition for clarity and rhythm, especially when the coordinated parts are not parallel (e.g., a definite noun and a possessive noun).

Why is mötet definite but kalender isn’t? Why not min kalendern?

mötet is definite because a specific meeting is meant (“the meeting”).
With possessives, Swedish does not use the definite ending: it’s min kalender, not ❌min kalendern. The possessive already makes it definite.

Can I rephrase it starting with Det beror på…?

Yes. Det beror på mötet och på min kalender hur sent vi stannar. Here, det is a dummy (expletive) subject, and the heavy clause hur sent vi stannar is postponed to the end. Both orders are correct; the “det …” version often feels natural in speech.

Is a comma needed after Hur sent vi stannar?

No. Swedish does not use a comma between a fronted subject clause and the main clause. Commas are used more sparingly than in English.

Why not beror av instead of beror på?

For “depend on / be due to,” the fixed preposition is på: bero på. You’ll see bero av in older/formal usage meaning “be dependent on,” but the modern, common pattern is:

bero på (depend on / be caused by)
vara beroende av (be dependent on/addicted to)

Should it be min or mitt with kalender?

kalender is an en-word (common gender: en kalender), so use min kalender. Neuter nouns (ett-words) take mitt (e.g., mitt schema), and plurals take mina (mina kalendrar/scheman).

Could I say Hur länge vi stannar beror på… instead? Does that change the meaning?

Yes, and it changes the nuance:

Hur länge vi stannar = how long (duration).
Hur sent vi stannar = how late (time-of-day). Choose the one that matches what you want to express.

Does stannar ever mean “stop,” and is there any ambiguity here?

stanna can mean both “stay/remain” and “stop.” Here, hur sent resolves the meaning to “stay” (how late we’ll stay). For “stop,” context typically includes a place or object: Bussen stannar här (The bus stops here).

Any other natural ways to phrase the sentence?

Hur länge vi blir kvar beror på mötet och min kalender.
Hur sent det blir beror på mötet och min kalender.
Det hänger på mötet och min kalender hur sent vi stannar. (colloquial)
Hur sent vi stannar avgörs av mötet och min kalender. (more formal)

Can I move the clause hur sent vi stannar to the end without det?

In standard written Swedish, no. If you move a heavy subject clause to the end, you normally introduce det as a dummy subject: Det beror på mötet … hur sent vi stannar. Without det, the main clause would lack a subject.