German Grammar Explained /

Wann, wenn, falls, als, ob.

These conjunctions can sometimes be tricky because in English they could all translate as “when” or “if/whether”. This can sometimes be confusing for language learners.
the are all subordinate conjunctions:
they introduce subordinate clauses
the conjugated verb is at the end of clause.
How are they used?
Let's break them up by function:
→ Temporal function
  • wann
Wann is a question word that goes at the beginning of sentences to ask about a point in time.
Wann kommt der Zug?
When is the train coming?
Bis wann musst du arbeiten?
Until when do you have to work?
Wann bist du angekommen? When did you arrive?
You can indirect questions vquestions as a placeholder for "(at) what time” or “at what point in time”.
Weißt du, wann der Zug kommt? Do you know what time the train is coming?
Er fragt seinen Chef, wann das Meeting ist.
He asks his boss when the meeting is.
Sag mir, wann du mich endlich besuchen kommst.
Tell me when you are coming to visit.
The other connectors can also be classified by their function:
Let's stay with time.
  • wenn - als
Wenn and als have a temporal function. They express that two things are happening or have happened at the same time. They are the answer to the question “when?”.
You use wenn to talk about something in the present or in the future.
Ich rufe dich an, wenn ich mit der Arbeit fertig bin. I will call you when I am done with work.
Wenn ich nach Hause komme, koche ich etwas. When I get home, I'm going to cook something.
Gehen wir etwas essen, wenn der Film zu Ende ist? Shall we go eat something when the film is over?
It is also used to talk about something in the past that took place repeatedly or at least more than once.
Jedesmal wenn ich komme, bist du beschäftigt. You're always busy when I come.
Wenn sie frei hatte, ist sie immer spazieren gegangen. She always went for a walk when she was free.
Es gab immer selbstgemachten Kuchen, wenn ich bei meiner Oma war.
When I used to go to my grandmother's, there were always home made biscuits to eat.
Als is used only for the past and when the action being talked about only happened once, even if it was something that took a long time.
Als ich gestern im Kino war, habe ich Franz getroffen.
I ran into Franz when I was in the cinema yesterday.
Ich habe mein Abitur gemacht, als ich 18 Jahre alt war.
I did my A-levels when I was 18 years old.
Als ich ein Kind war, habe ich auf dem Land gewohnt.
When I was a child, I used to live in the countryside.
→ Conditionl function

  • wenn - falls
Wenn can also sometimes mean "if". In this case, it's all about conditions. When you use wenn or falls, you need a prerequisite or condition that must be fulfilled for something to take place. This condition goes in the subordinate clause.
There is a small difference between wenn and falls:
If you use wenn, it is more likely that the condition will be met.
Ich besuche dich morgen, wenn es dir recht ist.
I'll visit you tomorrow if that's all right with you.
(We had already spoken about this.)
Wenn du Hunger hast, können wir etwas bestellen.
If you're hungry, we can order something.
(Your stomach is already growling)
With falls, the likelihood of the event actually happening is lower. There is a lower chance that the condition(s) can be met.
Falls ich Zeit habe, komme ich noch vorbei
If I have time I'll come over
(...aber ich habe noch viel zu tun).
(...but I still have a lot to do).
Ich nehme morgen das Fahrrad, falls es nicht regnet
I'll ride my bike tomorrow if it doesn't rain
(...aber der Wetterbericht sagt schlechtes Wetter voraus).
(...but the forecast says the weather will be bad).
And finally, the last one:
  • ob

Ob is used to make indirect questions. It expresses that you don’t know something that you would like to know. It goes after a question to express doubt or uncertainty and also if you want to ask a yes/no question.
If you could possibly say “whether” in English, in German you must always use ob. If not, use wenn.
Ich weiss nicht, ob das stimmt. (ja/nein?)
I don't know whether that's right. (yes/no?)
Sie möchte wissen, ob du ihr helfen kannst.
She would like to know whether you can help.
Ich bin nicht sicher, ob dieser Laptop genug Speicherplatz hat.
I am not sure whether this laptop has enough storage capacity.
Er hat mich gefragt, ob ich ins Kino gehen möchte.
He asked me whether I wanted to go to the cinema.
It is often also the case that people ask a question using a subordinate indirect clause starting with ob to make it sound more polite.
Können Sie mir sagen, ob dieser Laptop genug Speicherplatz hat? Could you tell me whether this laptop has got enough storage capacity?
Darf ich Sie fragen, ob Sie diese App benutzen?
Could I ask you whether you use this app?
Once more:
- Und jetzt möchte ich gerne wissen, ob du alles verstanden hast. And now, I'd like to know whether you have understood it all.
- Ich bin nicht sicher, ob die Erklärung verständlich ist.
I am not sure whether this explanation was clear.
- Ich freue mich, wenn du alles verstanden hast.
I'm glad if you understood everything.
- Wenn du möchtest, machen wir weiter.
If you like, we can carry on.
That's it! :)