English has one word, "when," for two very different situations, and Danish splits them: da marks a single, specific event in the past, while når marks events that repeat (in any tense) or that lie in the future. Because English hides the distinction, this is the kind of error that survives long into a learner's Danish — but the rule itself is short enough to memorise in a minute.
The quick answer
- A single, specific past event ("on that one occasion in the past") → da
- A repeated/habitual event (any tense) or a future event → når
The fastest mental test pairs each word with a quantity phrase:
- If you could add én gang ("once," that one time) → da
- If you could add hver gang ("every time," again and again) or it hasn't happened yet → når
Da — one specific moment in the past
Da points to a single, completed point in past time: the day you were born, the moment you met someone, the year something happened. There is one occasion, and it's behind us.
Da jeg var barn, boede vi i Aarhus.
When I was a child, we lived in Aarhus.
Da jeg så ham, vidste jeg det med det samme.
When I saw him, I knew straight away.
Hun blev meget glad, da hun fik beskeden.
She was very happy when she got the message.
Each of these describes a one-time past situation: that childhood, that moment of seeing him, that message. You could append "that one time" to any of them. That uniqueness-in-the-past is the signature of da.
A small but important point of Danish word order: after the time clause comes first, the main clause inverts (verb before subject): Da jeg var barn, *boede vi… — literally "lived we." This is the V2 rule and applies after both *da and når.
Når — repeated events, general truths, and the future
Når covers everything else. Its two main jobs:
1. Habitual / repeated events — things that happen again and again, often best translated "whenever." These can even be in the past, as long as they recurred.
Når jeg er træt, drikker jeg en kop kaffe.
When(ever) I'm tired, I drink a cup of coffee.
Når det regner, tager hun altid paraply med.
When(ever) it rains, she always brings an umbrella.
Da jeg var ung, gik jeg altid en tur, når jeg var ked af det.
When I was young, I always went for a walk whenever I was sad.
That last sentence is the clearest teaching case: da jeg var ung is the single backdrop of "my youth" (one past stretch → da), but når jeg var ked af det is the repeated trigger "every time I was sad" (recurring → når, even though it's the past). The word altid ("always") is a giveaway that you're in når territory.
2. The future — anything that hasn't happened yet uses når, even a single specific occasion.
Når jeg kommer hjem i aften, laver jeg mad.
When I get home tonight, I'll cook.
Vi ringer til dig, når toget ankommer.
We'll call you when the train arrives.
Coming home tonight is a single event, but it's in the future, so it's når, not da. Da is locked to the past — it can never point forward.
The minimal contrast
The same verb, the same subject, but a different "when":
Da jeg så ham, smilede han. (én gang — den ene gang)
When I saw him, he smiled. (one specific past time)
Når jeg ser ham, smiler han. (hver gang — generelt)
When(ever) I see him, he smiles. (every time, as a rule)
Da jeg så ham = a single past encounter. Når jeg ser ham = the general pattern, present tense, every time it happens. Swapping da for når doesn't just change the grammar — it changes whether you're describing one event or a recurring habit.
A note on the other da (briefly)
Da has two further uses you'll meet, which you can set aside while learning the temporal rule but should recognise:
- Da meaning "since / as / because" (causal), close to fordi: Da det var sent, gik vi hjem ("Since it was late, we went home").
- Da as a modal particle sprinkled into speech for emphasis or mild contradiction (informal): Det er da ikke rigtigt! ("But that's not true!"). Here da isn't "when" at all and carries no time meaning.
These don't interfere with the da-vs-når "when" decision — they just share the spelling. When you're choosing between the two "whens," only the single-past-event rule matters.
Edge cases
Asking "when?" as a question — neither da nor når. Direct questions use hvornår: Hvornår kommer du? ("When are you coming?"). Da and når are conjunctions joining clauses, not question words. Indirect questions also take hvornår: Jeg ved ikke, hvornår han kommer ("I don't know when he's coming").
A one-off in the past you're narrating as a sequence — still da. Even in a story where one thing follows another, each single past "when" is da: Da hun åbnede døren, stod han der ("When she opened the door, he was standing there").
Repeated past with no "always" word — still når. You don't need altid for the habitual reading; the recurrence can be implied: Min mormor sang, når hun lavede mad ("My grandma used to sing when she cooked") — a recurring habit in the past, so når.
Common Mistakes
The overwhelmingly common error is using når for a single past event, because English "when" gives no warning.
❌ Når jeg blev født, boede mine forældre i Odense.
Incorrect — being born is a single past event → da.
✅ Da jeg blev født, boede mine forældre i Odense.
When I was born, my parents lived in Odense.
❌ Når jeg mødte hende første gang, var jeg nervøs.
Incorrect — 'the first time I met her' is one past occasion → da.
✅ Da jeg mødte hende første gang, var jeg nervøs.
When I met her the first time, I was nervous.
❌ Da jeg kommer hjem, ringer jeg til dig.
Incorrect — this is in the future; da can't point forward → når.
✅ Når jeg kommer hjem, ringer jeg til dig.
When I get home, I'll call you.
❌ Da det regner, bliver jeg hjemme.
Incorrect — a general/habitual rule, not one past time → når.
✅ Når det regner, bliver jeg hjemme.
When(ever) it rains, I stay home.
❌ Da kommer du?
Incorrect — a direct question needs hvornår, not da/når.
✅ Hvornår kommer du?
When are you coming?
The cure: before you write "when," ask whether it points to one past moment. If it does, write da. If it's recurring or future, write når.
Decision flowchart
| Question | Answer | Use | Example |
|---|---|---|---|
| Is it a direct or indirect question ("when?")? | Yes | hvornår | Hvornår kommer du? |
| Otherwise: one specific event in the past? | Yes (én gang) | da | Da jeg var barn… |
| Repeated/habitual ("whenever," any tense)? | Yes (hver gang) | når | Når jeg er træt… |
| In the future? | Yes | når | Når jeg kommer hjem… |
Key takeaways
- Da = one specific event in the past (think én gang — that one time). It can never refer to the future.
- Når = repeated/habitual ("whenever," hver gang) or the future.
- The trap is purely English's fault: one word "when" for both. Always check whether your "when" is a single past moment.
- Questions ("when?") use neither — they use hvornår.
Now practice Danish
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Start learning Danish→Related Topics
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- Using Når for a Single Past EventA2 — Why English speakers wrongly use når for one-off past events, when da is required, and the one case where past når is actually correct.
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