The infinitve marker "to" can not simply be translated with "zu". Apparently in most instances it translates with "um zu", wheras in other instances "zu" alone is used.

1 "Del" is the key to press.
- "Entf" ist die zu drückende Taste.

2 "Del" is the key to delete letters.
- "Entf" ist die Taste, um Buchstaben zu löschen.

3 Press "Del" to delete letters.
- Drücken Sie "Entf", um Buchstaben zu löschen.

4 It is a bad idea to press "Del".
- Es ist keine gute Idee "Entf" zu drücken.

Are there any rules of when to use "zu" and when to use "um zu"? Is it a good style to translate "to" with "um zu" or is it be more elegant to avoid the infinitive (e.g. in 2 "Die "Entf"-Taste löscht Buchstaben")?

  • 1
    Funny to read these early questions that you asked to produce traffic.
    – Carsten S
    Jul 17, 2015 at 23:18
  • to is not to be translated. to is an inherent part of an infinitive in English language. It is a grammatical particle, there for inherently grammatical reasons just like um zu or zu — or the French à and de. The only difference is that some modal verbs in English require a stem form (Stammform) of a verb rather than the infinitive: One must do something. As such, I’m giving the question –1.
    – Jan
    Jul 23, 2015 at 9:46
  • @Jan now, is your comment in any way helpful for somebody who has doubts on deciding when to use zu, or um zu on translating such an infinitive construction from English to German? This was what I had asked here, it really was not about the usage of infinitive constructions in general. More precisely, in the very early days of GL I had mainly asked it for us to find out what kind of questions may be possible here. In case you feel that today such a question would not be a good fit, then please go to German Language Meta to discuss this.
    – Takkat
    Jul 23, 2015 at 10:27
  • If somebody is doubting whether to use zu or um zu, they should first have to realise that the distinction is required by German grammar and has nothing to do with the language one is translating from. So a differently worded question asking essentially the same thing only coming from ‘when creating infinitive constructions in German, which choice should I make when?’ without using the English to as an anchor would deserve a +1 from me.
    – Jan
    Jul 23, 2015 at 10:35

3 Answers 3


The um zu part has already been explained. When you can replace your to by in order to or rephrase to because I want to, then um zu is the correct choice.

What I would like to add is a method to check for a simple zu. Imagine a room full of people. You open the door and you say the first part of your sentence and then you leave. If you can do that without confusing everyone, it is probably um zu, but if your sentence does not make any sense by itself, it is going to be zu.


I am trying.

Unless you have discussed whatever you are trying before, this statement is nonsense. It needs the to part as completion and thus is followed by just zu in German.

Ich versuche zu lesen.

”I am trying“ is not complete. Now let’s look at a sentence that is:

I am going to the kitchen, (to get a beer).

People might wonder who cares but still they are well-informed about your plans.

Ich gehe in die Küche, um ein Bier zu holen.

So when the first part doesn’t make sense by itself, the to is mostly translated to zu.

There is one more thing that needs to be mentioned. If you want to connect a modal verb like können or wollen with an infinite form, the to just disappears. For instance:

I want to eat.
Ich will essen.

I have to go.
I must go.
Ich muss gehen.

This also applies for gehen by the way.

I go to the supermarket to buy milk.

According to the in order to rule the translation should be:

Ich gehe in den Supermarkt, um Milch zu kaufen.

This is correct but the following is also proper:

Ich gehe in den Supermarkt Milch kaufen.

So here the to disappeared as well.


Expanding on @Stefan Walter's statement...

"Um" with "zu" always starts a subordinate clause describing an aim or a purpose.

The construct um [etwas] zu [infinitiv] more literally translates to the English phrase in order to [do something]. It just happens that the phrase isn't terribly common in English. "Zu" is used alone for simply convey an infinitive verb. Following this definition, the meanings of your examples 2 and 3 change slightly (though you don't have to change the English wording):

2 "Del" is the key [to press - implied] in order to delete letters. - "Entf" ist die Taste, um Buchstaben zu löschen.

3 Press "Del" in order to delete letters. - Drücken Sie "Entf", um Buchstaben zu löschen.

If there is no object of the action, you don't need the "um".


"Um" with "zu" always starts a subordinate clause describing an aim or a purpose. This is clearly not the case in ¹ and ⁴.

³ sounds good. ² does not, since one would expect the clause "um Buchstaben zu löschen" to refer to an action and not to an object. I suggest:

"Entf" ist die Taste, mit der man Buchstaben löscht (löschen kann).

Of course, in a manual, it might be appropriate to use "Sie" instead of "man".

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