wenn. When or if: the verb goes last.

wenn covers two English words at once: "when" and "if." It works for the present, the future, and repeated situations. Like weil and dass, it sends the verb to the very end of the clause.

Two meanings, one word

English uses two separate words: "when" for time and "if" for conditions. German uses wenn for both. The meaning is usually clear from context.

English	German	Type
When I get home, I eat.	Wenn ich nach Hause komme, esse ich.	Time (present)
If it rains, we stay inside.	Wenn es regnet, bleiben wir drinnen.	Condition
When she arrives, I'll answer.	Wenn sie kommt, antworte ich.	Time (future)
If you want, we can go.	Wenn du willst, können wir gehen.	Condition

The verb goes to the end

wenn follows the same rule as weil and dass. The verb leaves position two and moves to the last slot in the clause.

Main clause	wenn	Subject	Middle	Verb (last)
Ich lerne mehr,	wenn	ich	Zeit	habe.
Wir gehen raus,	wenn	dieSonne		scheint.
Er schreibt,	wenn	er	in Berlin	ist.

The clause can move to the front

Like weil and dass, a wenn clause can come first. When it does, the main clause inverts: the verb comes before the subject.

wenn clause first	Verb	Subject	Rest
Wenn ich Zeithabe,	lerne	ich	mehr.
Wenn es regnet,	bleiben	wir	drinnen.
Wenn du willst,	können	wir	gehen.

The comma between the two halves is always required.

wenn for repeated past situations

wenn can also describe something that happened repeatedly in the past, a habit, a pattern, something that kept happening. The key word is "every time" or "whenever."

• Wenn wir Urlaubhatten, fuhren wir ans Meer. (Whenever we had holidays, we went to the sea.)
• Wenn er müde war, schlief er früh. (Whenever he was tired, he went to bed early.)

This is where wenn and als diverge. wenn covers habits and patterns. als covers a single, specific moment. "When I was a child" describes one continuous period, not a repeated pattern, so it takes als, not wenn.

The full explanation of when to use als: als. One moment in the past. Same verb-last rule explained from the start: weil. The verb goes last. Often confused with the question word that looks similar: wenn vs. wann. Two words, one English word.