When to Use "zu" with German Infinitive Clauses

Herr Antrim: If the following scene feels familiar, this lesson is for you. I’ll explain when you need to use “zu” with an infinitive and when you don’t. And I’ll show you how these infinitive clauses with “zu” differ from relative clauses with “dass”.

Deutschlerner: Ich will heute Deutsch zu lernen. -
I want to learn German today.

Herr Antrim: You don’t need “zu” with that sentence.

Deutschlerner: Ich sehe heute einen Film, anstatt mein Deutschbuch lesen. -
I am watching a movie today instead of reading my German book.

Herr Antrim: Maybe you should read that book instead. You need “zu” in that sentence.

Deutschlerner: Ich verstehe nicht, was ich tun muss um Deutsch lernen. -
I don’t understand what I have to do in order to learn German.

Herr Antrim: You need “zu” in that one, too.

Deutschlerner: Jetzt reicht’s! Ich gehe jetzt zu essen. -
That’s enough. I am going to eat now.

Herr Antrim: You actually don’t need “zu” in that one.

Deutschlerner: AHHHH!!! What is going on? Sometimes you need “zu”. Sometimes you don’t. Infinitives in English almost always have “to” in front of them. Why don’t you need “zu” in German? This makes no sense!

What are Infinitive Clauses?

First, let’s define what we are talking about. Phrases that use “zu” plus an infinitive are called infinitive clauses. These are a type of dependent clause that don’t technically have a subject. Basically it is like having an extra half to a sentence that isn’t complete as it doesn’t show who is acting stuck to the end of another sentence. The subject is generally shown in the first clause and the infinitive clause implies that same subject, but it doesn’t have to be this way. For example:

Er versucht, uns die Grammatik zu erklären. -
He attempts to explain the grammar to us.

The subject of both halves is “er”, but the second clause doesn’t include “er”. Instead it implies that the subject is the same without actually naming it. You can clearly see this if you break the two clauses apart into two separate sentences.

Er versucht. Er erklärt uns die Grammatik. -
He attempts. He explains the grammar to us.

Now you can clearly see that the subject of the two clauses is the same. When we eliminated the second version and made it into a dependent clause, we added “zu” and changed the verb “erklärt” back into the infinitive form “erklären”. Let’s try a few more examples.

Der Verbrecher hat vergessen, seine Fingerabdrücke zu entfernen. -
The criminal forgot to remove his fingerprints.

As I mentioned before, the subject of the first clause does not have to be the same as the subject implied within the dependent clause. For example:

Es wundert ihn, ins Gefängnis geworfen zu werden. -
It surprised him to be thrown in jail.

In the first clause the ambiguous “es” (it) is the subject whereas the second clause implies that “er” (he) is the subject. As mentioned before the subject of the dependent clause is not explicitly stated, which is why we still use the “zu” plus an infinitive.

Independent Clauses

This only works if the second clause we say or write is a dependent clause. If we drop the subject out of the second half of a normal sentence, this does not happen. For example:

Er nimmt seine Spielzeuge und geht nach Hause. -
He takes his toys and goes home.

He is the subject of both halves of the sentence, but the conjunction “und” (and) doesn’t trigger a dependent clause, so we keep the conjugated form of “gehen”, “geht”.

Subordinate Clauses

Even if we use a subordinating conjunction, which triggers a subordinate clause (similar to a dependent clause, but not quite), we still don’t use the “zu” plus infinitive format, as we keep the subject in the second half of the sentence.

Er ging nach Hause, weil er geärgert wurde. -
He went home because he was annoyed.

In this example, the verb was pushed to the end of the sentence, but the subject is still there to tell the verb which form to take. Therefore we don’t need the “zu” plus infinitive construction.

This includes examples that use the conjunction “dass”, which is sometimes tricky to understand for German learners. “Dass” generally is translated as “that”, but this logic doesn’t always work out.

Er hat herausgefunden, dass er im Lotto gewonnen hat. -
He found out that he won the lottery.

The confusion with this conjunction occurs when you want someone to do something. In English the action you want the other person to do is contained within an infinitive clause, which includes “to”. In German, you simply use the conjunction “dass” and you don’t need the infinitive clause for the reasons I have already mentioned. Here are a few examples of that.

Ich will, dass du mich willst. -
I want you to want me.
♩ ♪ ♫ ♬ I need you to need me. I’m begging you to beg me. ♩ ♪ ♫ ♬

Er möchte, dass sie ihm Abendessen kocht. -
He wants her to cook him dinner.

Sie möchte, dass er kein Frauenhasser ist. -
She would like him to not be a misogynist.

Lust haben

Be careful with this thought process, however, as you would use an infinitive clause after a phrase involving “Lust haben”, which still shows desire to do something. The difference is that you aren’t wanting someone else to do something with “Lust haben” in those phrases.

Er hat keine Lust, ins Kino zu gehen. -
He doesn’t want (has no desire) to go to the movies.

If you do want to show a desire for someone else to do something after “Lust haben”, you can do so, but you have to go back to using “dass” and no infinitive clause.

Haben Sie Lust, dass wir Ihnen die Stadt zeigen? -
Do you have a desire for us to show you the city?

Modal Verbs

Now, what about modal verbs or modal auxiliaries? Why don’t you use “zu” with them. “To” is needed in English. Why isn’t it in German? The same reasons as before. The subject is named in sentences with modal verbs and there is no dependent clause. It lacks both requirements for the infinitive clause to be used.

Ich will Deutsch lernen. -
I want to learn German.

Wir müssen die Grammatik verstehen. -
We have to understand the grammar.

Prepositions That Trigger Infinitive Clauses with zu

Back to the examples that do use infinitive clauses, it is often stated that “anstatt”, “um” and “ohne” are used to create these kinds of clauses. It is important to note that these words actually just facilitate the creation of a dependent clause and are not actually the cause of the infinitive clause. The infinitive clause is created by having a dependent clause that does not have a subject explicitly stated in it. For example:

Er geht nach Hause, anstatt mit seinen Freunden zu bleiben. -
He goes home instead of staying with his friends.

Er geht nach Hause, um etwas zu essen. -
He goes home in order to eat something.

Er geht nach Hause, ohne seinen Freunden “auf Wiedersehen” zu sagen. -
He goes home without saying goodbye to his friends.

Notice that in English we use the verb form with -ing at the end with “instead of” and “without”, but an infinitive clause with “to” when we use “in order”. This discrepancy is generally why these phrases are difficult for English speakers to translate. The bottom line is still the same, however. The subject is missing from the dependent clause. Using “anstatt”, “ohne” or “um” to facilitate this clause is not necessary for you to understand why you need “zu” with an infinitive.

Adjectives & Adverbs That Trigger zu + Infinitive Clauses

There are a few more weird ways that infinitive clauses are used in German. These generally have to do with adding an adverb or adjective to describe the action that takes place in the dependent clause. The grammar is still the same. The subject is not present in a dependent clause, but I thought it would be helpful to see some examples like that, too.

Es ist schön Sie zu treffen. -
It is nice to meet you.

Es ist jetzt meine Gewohnheit, bis acht im Bett zu bleiben. -
It is now my habit to stay in bed until eight.

Es muss schön sein, so viel Geld zu haben. -
It must be nice to have so much money.

Es ist tragisch, diesen Mann so zu sehen. -
It is tragic to see this man like this.

zu + Infinitive Clauses as the Subject

You can also use an infinitive clause as the subject of a sentence, in which case it goes at the beginning of the sentence.

Dieses Video zu verstehen ist ganz einfach. -
Understanding this video is very simple.

Herrn Antrim zu mögen ist sehr schwer. -
It is very difficult to like Herr Antrim.

Deutsch zu lernen ist nicht schwer. -
Learning German is not difficult.

How to Create zu + Infinitive Clauses

Alright. Now that we have the general rules for when you need to use infinitive clauses, let’s get to the how. As you have seen in most of my examples, you use the verb you normally would have conjugated in the infinitive form right after “zu”. This works when you only have one verb in the clause.

Ich vergesse immer, mein Auto zu schließen. -
I always forget to lock my car.

When you use a modal verb, you put the modal verb directly after “zu” and the other verb directly before it. Both of them should be in the infinitive form.

Es ist nicht gut, immer etwas essen zu wollen. -
It is not good to always want to eat something.

Es ist besser zweimal nachzudenken als sich einmal entschuldigen zu müssen. -
It is better to think twice than to have to apologize once.

As you can see in the last example, if you have a separable prefix in the verb that you need in the infinitive clause, you put the “zu” between the prefix and the rest of the verb. This all remains as one word. You can also see the modal verbs are directly after the word “zu” and the other verb is directly before “zu”.

All of those examples are in the present tense. What if we want to write in the past? You can kind of imply all of the other tenses through the main clause, for example:

Präsens

Es ist ihm eine Freude, die Kinder wiederzusehen. -
It is a joy for him to see the children again.

Learn about the Präsens tense here.

Präteritum

Es war ihm eine Freude, die Kinder wiederzusehen. -
It was a joy for him to see the children again.

Learn about the Präteritum tense here.

Perfekt

Es ist ihm eine Freude gewesen, die Kinder wiederzusehen. -
It was a joy for him to see the children again.

Learn about the Perfekt tense here.

Plusquamperfekt

Es war ihm eine Freude gewesen, die Kinder wiederzusehen. -
It had been a joy for him to see the children again.

Learn about the Plusquamperfekt here.

Futur 1

Es wird ihm eine Freude sein, die Kinder wiederzusehen. -
It will be a joy for him to see the children again.

Learn about Futur 1 here.

Futur 2

Es wird ihm eine Freude gewesen sein, die Kinder wiederzusehen. -
It will have been a joy for him to see the children again.

Learn about Futur 2 here.

Tenses Explicitly Expressed in zu + Infinitive Clauses

If you want to show the tense in the infinitive clause, it is a bit more difficult. You can’t really explicitly use any of the tenses except the past in an infinitive clause. In all of the examples I just showed you, the infinitive clause doesn’t actually show a tense at all. It shows a tense in the main clause.

If you want to show for sure that the dependent clause and subsequently the infinitive clause is taking place in the past, you need to use a version of the Perfekt tense.

To form the Perfekt tense, you use a past participle and a helper, either “haben” or “sein”. When you put this into an infinitive clause, the past participle goes before “zu” and the infinitive of either “haben” or “sein” goes after it. You choose between “haben” and “sein” in the same way you usually would for the Perfekt tense. Link in the description for a video about the Perfekt tense and how all of that works. In the meantime, here are a few examples of the Perfekt tense with infinitive clauses.

Sie behauptet, ihr Handy verloren zu haben. -
She claims to have lost her cell phone.

Er hofft, die Prüfung bestanden zu haben. -
He hopes to have passed the test.

Wir versprechen, vor nächstem Donnerstag den Aufsatz geschrieben zu haben. -
We promise to have written the essay before next Thursday.

Now that you understand these clauses, it is time to learn about other kinds of clauses. Click one of the links below to continue learning. 

Subordinating Conjunctions with Subordinate Clauses 

Relative Pronouns and Relative Clauses