Als and Wenn are two conjunctions both used in temporal subordinate clauses and both mean „when“, both answering the question Wann?, so it is very easy to mistakenly think that these 2 words are used the same way and can replace each other in every case. This is a basic grammar mistake that many people make while learning German at A1. So let's find out the difference between Als and Wenn in the article below!!

1) When is Als used?

- Als is only used for events and actions that happened in the past and took place only once.

Ex. 1: Als sie 29 Jahre alt war, heiratete sie. (She got married when she was 29)

We use als in this case because she went through the age of 29 only once in her life.

Ex. 2: Sie war sehr frech, als sie jung war. (When she was young, she was very naughty)

The event of being young happens only once in each person's life, so we use als to describe it.

2) When is Wenn used?

- Used to express actions or events that happened many times or repeatedly in the past, through the adverb jedes Mal.

Ex.: Sie aß jedes Mal einen großen Hamburger wenn sie Hunger hatte. (Every time she was hungry, she ate a really big Hamburger )

The sentence above expresses an action repeated over and over in the past, so we use the conjunction Wenn.

- In addition, Wenn is also used in both the present tense and the future.

Ex. 1: Wann fängst du mit Schule an? (When do you start school?)

Ich fange jedes Jahr mit der Schule an, wenn der September beginnt. (I start school at the beginning of September every year.)

In the sentence above, Wenn is used because the event of my going to school happens every year, repeating in the present.

Ex. 2: Ich werde dich morgen begleiten, wenn du zum Flughafen gehst. (Tomorrow, I will go with you when you go to the airport .)

Wenn is used in the future tense through the adverb morgen.

Ex. 3: Hannah ist immer schüchtern, wenn sie neue Leute kennenlernt. (Hannah is always shy when she meets new people.)

Besides the adverb jedes Mal, immer also often appears in a sentence to indicate an action repeated many times.