The problem starts the moment a learner tries to say "when I was a child." In English that's a single phrase with a single word. In German you need to choose: als ich ein Kind war — and if you write wenn ich ein Kind war or wann ich ein Kind war, both are wrong in different ways. One implies the situation was repeated or conditional. The other turns the sentence into a question.
The three words cover non-overlapping territory. Get the territory right and the choice becomes automatic.
The Three-Way Split at a Glance
| Word | Use | Tense |
|---|---|---|
| als | Single, one-time event or period in the past | Past only |
| wenn | Repeated events (past or present); present or future situations; conditional "if" | Any tense |
| wann | Direct questions and indirect questions about time only | Any tense |
Als — Single Event in the Past
Als introduces a subordinate clause describing a single, one-time event or period that happened in the past. It cannot be used for the present or future, and it cannot be used for repeated events — even in the past.
Als ich ein Kind war, wohnte ich in München.
When I was a child, I lived in Munich. (one period in the past)
Als er ankam, fing der Regen an.
When he arrived, it started raining. (two single past events)
Als sie die Nachricht hörte, wurde sie blass.
When she heard the news, she turned pale.
Als ich zwanzig war, bin ich nach Berlin gezogen.
When I was twenty, I moved to Berlin.
Als das Konzert zu Ende war, applaudierten alle.
When the concert ended, everyone applauded.
Als is a subordinating conjunction — it sends the verb to the end of its clause. It always refers to a specific, unrepeatable moment or stretch of time in the past. Think of it as describing a scene that happened exactly once.
Wenn — Repeated Events and Present/Future
Wenn covers two situations: events that happen or happened repeatedly (in any tense), and single events in the present or future. It is also the word for "if" — which is covered in the next section.
Repeated events — any tense:
Wenn ich als Kind krank war, brachte mir meine Mutter Tee.
When(ever) I was sick as a child, my mother brought me tea. (repeated past situation)
Wenn es regnet, nehme ich einen Regenschirm.
When(ever) it rains, I take an umbrella. (habitual present)
Wenn wir uns früher getroffen haben, sind wir immer ins Café gegangen.
Whenever we used to meet, we always went to the café.
Single present or future events:
Wenn du fertig bist, können wir gehen.
When you're done, we can leave.
Ruf mich an, wenn du angekommen bist.
Call me when you've arrived.
Wenn ich mehr Zeit habe, lese ich mehr.
When I have more time, I read more.
The repetition test
If you can naturally add "whenever" to the English sentence without changing the meaning, the German is almost certainly wenn. If "whenever" sounds wrong — because it happened exactly once — the German is als (assuming past tense).
Wann — Questions and Indirect Questions Only
Wann is a question word. It introduces direct questions about time and indirect questions (embedded questions inside a statement). It never introduces temporal clauses the way als and wenn do.
Direct questions:
Wann kommt der Zug?
When does the train come?
Wann bist du geboren?
When were you born?
Wann habt ihr geheiratet?
When did you get married?
Indirect questions (embedded inside a statement):
Ich weiß nicht, wann der Zug kommt.
I don't know when the train comes.
Er hat gefragt, wann wir ankommen.
He asked when we're arriving.
Kannst du mir sagen, wann das Geschäft öffnet?
Can you tell me when the shop opens?
Ich frage mich, wann er zurückkommt.
I wonder when he'll be back.
Wann introduces a subordinate clause in indirect questions — verb goes to the end, just like any subordinating element. But the clause it introduces is always a question embedded inside a larger sentence, not a time clause linking two events.
The Decision Tree
Three questions, in order:
1. Is this a question about time — direct or embedded?
Yes → wann.
No → continue.
2. Is the tense past?
No (present or future) → wenn.
Yes → continue.
3. Did it happen once, or repeatedly?
Once → als.
Repeatedly / habitually → wenn.
Als vs. Wenn in the Past — The Key Distinction
This is where most errors happen. Both als and wenn can refer to the past — the difference is whether the event happened once or repeatedly.
Als ich klein war, hatte ich Angst vor Hunden.
When I was small, I was afraid of dogs. (one continuous period — als)
Wenn ich als Kind einen Hund sah, bekam ich Angst.
Whenever I saw a dog as a child, I got scared. (repeated reaction — wenn)
Als er die Prüfung bestand, war er erleichtert.
When he passed the exam, he was relieved. (one specific exam — als)
Wenn er eine Prüfung bestand, feierte er immer.
Whenever he passed an exam, he always celebrated. (repeated pattern — wenn)
Als wir in Wien lebten, gingen wir oft in die Oper.
When we lived in Vienna, we often went to the opera. (one period — als)
Wenn wir in Wien waren, gingen wir immer in die Oper.
Whenever we were in Vienna, we always went to the opera. (repeated visits — wenn)
The adverbs are a useful signal: words like immer, oft, manchmal, jedes Mal in the sentence strongly suggest wenn because they imply repetition.
Wenn Also Means 'If'
Wenn covers both "when" (for present/future and repeated events) and "if" (for conditional situations). In many sentences the two meanings overlap — a conditional situation and a future "when" are grammatically identical in German.
Wenn es morgen regnet, bleibe ich zu Hause.
If/when it rains tomorrow, I'll stay home. (conditional and temporal at once)
Wenn du Zeit hast, ruf mich an.
If/when you have time, call me.
Context usually makes the intended meaning clear. The grammatical construction is identical either way — German doesn't distinguish between "if" and "when" for present and future situations. This is one area where German is actually simpler than English.
Falls for unambiguous 'if'
When you specifically want to express a conditional "if" — not "when" — German has falls (in case, if). Falls es morgen regnet, bleibe ich zu Hause is unambiguously conditional. Wenn works too, but falls removes the ambiguity. For real conditions that may or may not happen, falls is the more precise choice.
Word Order With All Three
All three are subordinating elements — they send the verb to the end of their clause. The same subordinate clause word order rules apply to all three.
Als er ankam, [fing der Regen an].
(als-clause in first position → main clause verb immediately follows)
Ich weiß nicht, [wann er ankommt].
(wann-clause at end of main clause — verb final)
Ruf mich an, [wenn du fertig bist].
(wenn-clause after the main clause)
One word order note specific to wann: in indirect questions, wann functions like other subordinating question words (wo, wie, warum, ob) — verb to the end, no inversion of subject and verb inside the clause.
Ich weiß nicht, wann er kommt. ✓
Ich weiß nicht, wann kommt er. ✗ (that's a direct question structure, not indirect)
Common Traps
Trap 1 — Using wenn for a single past event
Als ich zwanzig war, bin ich ausgezogen. ✓
Wenn ich zwanzig war, bin ich ausgezogen. ✗ (implies it happened repeatedly, which makes no sense)
Trap 2 — Using als for present or future
Wenn ich nach Hause komme, esse ich etwas. ✓
Als ich nach Hause komme, esse ich etwas. ✗ (als cannot refer to present or future)
Trap 3 — Using wann in a time clause instead of a question
Als/Wenn er ankommt, rufe ich dich an. ✓
Wann er ankommt, rufe ich dich an. ✗ (wann cannot link two events — it's for questions only)
Trap 4 — Inverting the subject in an indirect wann-question
Ich weiß nicht, wann er kommt. ✓
Ich weiß nicht, wann kommt er. ✗
Trap 5 — Missing the repetition signal in a past sentence
Wenn ich als Kind krank war, blieb ich zu Hause. ✓ (repeated — wenn)
Als ich als Kind krank war, blieb ich zu Hause. ✗ (implies one specific illness)
Quick Recap
- German splits English "when" into three words that cover non-overlapping territory.
- Als — single, one-time event or period in the past only. Cannot refer to the present, future, or repeated events. Als ich klein war…
- Wenn — repeated or habitual events (any tense) and all present/future "when" situations. Also means "if." Wenn es regnet…
- Wann — direct questions about time and indirect (embedded) questions about time only. Never links two events. Wann kommt er? / Ich weiß nicht, wann er kommt.
- The decision tree: question about time? → wann. Present or future? → wenn. Past and repeated? → wenn. Past and single? → als.
- Repetition signals like immer, oft, manchmal, jedes Mal in the sentence point to wenn even in past contexts.
- Wenn and "if" are the same word in German for present and future situations. Falls is available when you want an unambiguously conditional meaning.
- All three send the verb to the end of their clause. In indirect wann-questions, do not invert subject and verb inside the embedded clause.