Weil vs. Denn | What's the difference?

💡Quick Answer

The German conjunctions "denn" and "weil" do not have a difference in meaning. If you can use "denn" in a sentence, you could have expressed the very same sentence using "weil" - and vice versa. However, you cannot just swap them out for one another.

While there is not difference in meaning between "weil" & "denn", they are not interchangable: You cannot simply take a sentence that uses "weil" and replace "weil" with "denn".

Weil & Denn Explained

Weil

The reason for this is that weil & denn "dock onto" different sentence structures. "Weil" requires a subordinate clause, whereas "denn" requires a main clause. Let's have a look at sentence using weil:

Ich trinke ein Glas Wasser, weil ich Durst habe.

What comes after "weil" cannot stand on its own. It's a subordinate clause. "Ich Durst habe" is not be a correct sentence in German.

Denn

"Denn", however, works differently to "weil". It introduces a main clause. So the very same sentence with "denn" has a slightly different word order:

Ich trinke ein Glas Wasser, denn ich habe Durst.

"Ich habe Durst" can stand on it's own: it's a main clause.

And this is the reason why you cannot just swap "weil" & "denn" out however you please.

Denn cannot stand at the beginning of a sentence

Another difference is that "denn" can never stand at the beginning of a sentence. You cannot introduce a sentence with "denn".

So you could say:

Weil ich Angst hatte, blieb ich in der Wohnung.

But you could not say:

Denn ich Angst hatte, blieb ich in der Wohnung.

Examples with weil & denn

Weil

Here are two more basic dialogues using "weil":

Warum warst du krank? Und wie lange?

Ich war die ganze letzte Woche krank, weil ich mich auf Katjas Hochzeit nicht warm genug angezogen habe!

Warum kommst du nicht mit auf das Konzert?

Weil ich leider kein Geld habe. Aber nächstes Mal komme ich mit!

Denn

And here are two example dialogues using "denn":

Ich freue mich auf das Konzert, denn ich war schon so lange nicht mehr aus!

Ich freue mich auch! Wann gehen wir?

Wieso seid ihr nicht pünktlich angekommen?

Wir mussten auf der Autobahn sehr langsam fahren, denn es regnete zu stark!