Temporal clauses with "wenn" and "als"

Wenn and als both translate as "when" — but German requires you to pick the right one depending on whether you're talking about the present, the future, or the past, and (in the past) whether you're describing a single, non-repeated situation or something that happened more than once. Like weil and dass, both are subordinating conjunctions: the finite verb moves to the end of the clause.

Quick shortcut: use als for a single, non-repeated reference point or period in the past. Use wenn for everything else — present, future, and anything repeated or habitual, including in the past.

Als: a single, non-repeated point or period in the past

Als isn't limited to a single instant — it also covers an entire period, as long as that period itself isn't being presented as repeating:

• Als ich zwölf Jahre alt war, bin ich nach Berlin gezogen. (When I was twelve, I moved to Berlin.) — one stretch of being twelve, not repeated
• Als sie ankam, regnete es. (When she arrived, it was raining.) — one specific arrival
• Als er das hörte, war er überrascht. (When he heard that, he was surprised.) — one specific moment of hearing the news

What these share isn't necessarily brevity — being twelve lasts a year — but that each names a single, non-repeated reference point in the past. Something can happen within that period more than once (more on that below) without changing which conjunction introduces the period itself.

Wenn: present, future, or anything repeated

Wenn covers three situations:

• Present: Wenn ich müde bin, trinke ich Kaffee. (When I'm tired, I drink coffee.)
• Future: Wenn ich nach Berlin komme, rufe ich dich an. (When I come to Berlin, I'll call you.)
• Repeated or habitual events in the past: Wenn ich ihn sah, haben wir immer lange geredet. (Whenever I saw him, we always talked for a long time.)

That last one is the trap: it's about the past, but wenn is still correct — not because the main clause mentions something habitual, but because seeing him itself was a recurring event, happening on many separate occasions. Compare that with Als ich Kind war, habe ich oft Fußball gespielt (When I was a child, I often played football): being a child is still a single, non-repeated period, so it takes als, even though oft ("often") makes the football-playing itself sound repeated. The repetition that matters is the one in the wenn/als-clause, not whatever happens inside the main clause.

Choosing between them

• Als ich sie das erste Mal traf, war sie Studentin. (When I met her for the first time, she was a student.) — one specific meeting → als
• Wenn ich sie traf, hatten wir immer viel Spaß. (Whenever I met her, we always had a lot of fun.) — many meetings → wenn
• Wenn ich sie treffe, freue ich mich. (When I meet her, I'm happy.) — present → wenn

Word order stays the same as weil/dass

Wenn and als are subordinating conjunctions too, so the same rules from weil and dass apply: the finite verb goes to the end of the clause, a comma always separates the two clauses, and if the wenn/als-clause comes first, the main clause's verb comes right after the comma:

• Als ich zwölf Jahre alt war, bin ich nach Berlin gezogen. (verb right after the comma, since the als-clause came first)
• Ich bin nach Berlin gezogen, als ich zwölf Jahre alt war. (verb at the end, since the als-clause came second)

A quick note on wenn and "if"

Wenn has a second, very common job: introducing a conditional clause ("if"), as in Wenn es regnet, bleibe ich zu Hause (If it rains, I'll stay home). The word order works exactly the same way — this article focuses on the temporal "when" use, but don't be surprised to see wenn meaning "if" elsewhere.

Common mistakes

• ❌ Wenn ich zwölf Jahre alt war, bin ich nach Berlin gezogen. → ✅ Als ich zwölf Jahre alt war, … (a single, non-repeated past period needs als, not wenn)
• ❌ Wenn ich Kind war, habe ich oft Fußball gespielt. → ✅ Als ich Kind war, … (being a child is still a single, non-repeated period, even though oft makes the football-playing itself sound repeated — the repetition that matters is in the wenn/als-clause, not the main clause)
• ❌ Als ich müde bin, trinke ich Kaffee. → ✅ Wenn ich müde bin, … (the present always takes wenn, never als)
• ❌ Als sie ankam, es regnete. → ✅ Als sie ankam, regnete es. (when the als-clause comes first, the main clause's verb comes right after the comma)

Quick check

Choose als or wenn:

1. ___ ich klein war, hatte ich einen Hund. (one specific period, described once)
2. ___ es regnet, nehme ich einen Regenschirm. (present, every time it happens)
3. ___ er anrief, war ich nicht zu Hause. (one specific phone call)
4. ___ wir uns trafen, haben wir stundenlang geredet. (every time we met, repeatedly)

Key takeaways

• Als is only for a single, non-repeated reference point or period in the past — it can be brief or last a long time, as long as it isn't presented as recurring.
• Wenn covers everything else: the present, the future, and genuinely repeated or habitual situations in the past.
• Repeated separate occasions in the past still take wenn, even though they're in the past — this is the most common mix-up.
• Wenn and als are subordinating conjunctions, following the same verb-final word order as weil and dass.
• Wenn also means "if" in conditional clauses — same word order, different meaning.