“wann” or “wenn” – What’s the difference

Hello everywann,

and welcome to our German Word of the Day and if you’re new here in 2021, welcome to your favorite German learning website. Seriously… all the other sites are okay, but this one is the most okay of them all.
Anyway, let’s get on with the topic, and today, we’ll take a look at the difference between

wann and wenn

Both of them are translations for when and lots of learners are struggling to tell when to use which.
But all we need is one beautifully simple test that I’ll call the Einstein-Check.
Because… it sounds smart.
And it has to do with time, so why not.
Anyway, let’s light speed jump right in…

The one important thing to realize is that wann is a question word asking for a point in time. That means we should be able to replace it with other phrases that also ask for time, without ruining the structure.
And that’s the Einstein-Check:

“If we can say at what point time instead of when, then we need to use wann.”

Let’s try it out. First, with direct questions.

• Wann kommt der Bus?
• What time/when does the bus come?
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• Seit wann lernst du Deutsch?
• Since when, what point in time have you been learning German?
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• Bis wann musst du arbeiten?
• Till when, what time do you have to work?
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• Von wann bis wann geht der Kurs?
• From what time, when till what time, when is the course?
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Now let’s do indirect question.

• Thomas fragt Maria, wann genau sie nach Hause kommt.
• Thomas asks Maria when, at what time exactly she is going to come home.
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• Ich werde meinen Chef fragen, bis wann er morgen im Büro ist.
• I will ask my boss, till when, what time he is going to be in the office tomorrow.
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• I know exactly when, at what time the bus comes.
• Ich weiß genau, wann der Bus kommt.

Seems to work great.
But let’s do a counter test.

• I’ll go home when at what time I am done.
• Ich gehe nach Hause, wenn wann ich fertig bin.

Perfect!
Here, changing when for at what time results in a nonsense sentence. And it’s the same in German, if we use wann instead of wenn.
So yeah, this simple test of replacing when with at what (point in) time is really all we need and if you just needed a quick fix, you can skip right down to the quiz and see if you really got it.

But we still have some time left here on our readable Podcast.
So I thought we could explore WHY the last example sounds so wrong with at what time in it.
Like… why can we sometimes replace when and sometimes we can’t?
There must be an underlying difference and by exploring that, we’ll not only increase our level of nerd, we’ll also get a nice view at how function is really really important in language. Something that’s really useful for German because German has a penchant for using different words for different functions.
So, if you have a little time, let’s geek out for a bit.

Grammar – making things simple

The difference between wann or wenn is actually pretty fundamental because they have different functions.
A wann-clause is ALWAYS functioning as the object of the verb.
For those of you who have read my article on the box-model (really important read :):
a wann-sentence is the what-box.
So… if I want to ask for a wann-sentence I would do that by asking what?
A wenn-sentence on the other hand functions as a TIME indication. So if I wanted to ask for it, I would ask at what time.
Ooof…. I’m feeling slightly confused. Quick let’s pop some Exampledine 20mg and see if that helps.

• Ich sage dir, [wann ich zu dir komme.]
• I tell you [when I am planning to come over to your place]
  
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• Ich sage dir [meinen Namen.]
• I tell you [my name.]
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You can see that my name and when I am planning to come over to your place have the same function…they fill the role of [something] in to say something.
Let’s do the same with to know something.

• Thomas knows [when to leave Maria alone.]
• Thomas weiß, [wann man Maria in Ruhe lassen sollte.]
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• Thomas weiß [viel über Deutsch.]
• Thomas knows [a lot about German.]
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Basically, whenever your when-sentence can be replaced by a thing, then you need to use wann in German and you do NOT need to think about whether it is an indirect question or not.

Now, let’s look at a wenn-sentence again. We said that it answers when (at what time).
Or in box speak: it fills a when-box. So it can be replaced by any other time indication.

• I’ll write you [when I have finished my work].
• Ich schreibe dir, [wenn ich meine Arbeit fertig hab’.]
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• I’ll write you [tonight].
• Ich schreibe dir [heut’ abend.]

And that’s all we need. No need for much thinking, just check what the when-clause is answering to:

if it answers to “what?” then use wann, if it answer to “what time?”, then use wenn.

Pretty simple, actually.
Let’s do a combination…

• [When I have finished work], I will call you and tell you [when I will be at home.]
• [Wenn ich mit der Arbeit fertig bin,] rufe ich dich an und sage dir, [wann ich zuhause bin.]
  [what time is the call?] [what will I tell you?]
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English relies on context here, which might be the reason why synonyms like as soon as or at what time are more common in English while German has a tendency to just use wenn. Because German uses two different words for two different functions – something that German likes to do :).

Cool.
So now we know what the difference is between wann and wenn.
But before we wrap up, let’s look at a few really useful phrasings and expressions with wann. Because… if not now then when :).

Some Common Phrasings

The first one is dann und wann, which translated to every now and then or other similar expressions.

• Dann und wann esse ich Sushi.
• Every now and then I eat Sushi.
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There are other ways to say this in German. For example ab und zu or hin und wieder those are more common than dann und wann.
And then there is wann anders.

• Heute schaffen wir das nicht mehr aber kein Problem, wir machen das einfach wann anders.
• We won’t be able to do it today, but no problem; we’ll just do it some other time.
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• Das muss ich dir mal wann anders erklären.
• I will have to explain that to you some other time.
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I am not sure as to whether this is a regional thing of northern Germany but I say it quite a lot. The “official” word would be ein andermal but wann anders just has more of a punchline character so I think that’s why people use it.
And finally there is the irgendwann which means at some point.

• Ich hab’ irgendwann letzte Woche deine Schwester gesehen.
• I have seen your sister some time last week.
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• Irgendwann will ich mal nach Neuseeland.
• I want to go to New Zealand at some point.
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• Hast du morgen irgendwann (mal) Zeit?
• Will you have time tomorrow at some point.
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Oh … and to be super-turbo-comprehensive, wann is also often used as whenever.

• Ruf an, wann du willst!
• Call, whenever you want!
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Cool.
So that’s it. This was our look at the difference between wann and wenn, and it really turned out not that big of a deal.
If you want to see if you can tell wenn and wann apart, you can take the little quiz I have prepared. But I have to warn you… I made it tricky :).
If you have any questions about it, or about the article, just leave me a comment.
I hope you liked it and see you next time.