Commonly Confused German Words Explained: kennen vs. wissen, wann vs. wenn, and More

Some German word pairs look similar, translate into the same English word, or show up in very similar situations. That is exactly why learners mix them up so often. The good news is that most of these pairs follow clear patterns once you know what to look for.

In this lesson, we will sort out several of the most commonly confused German words so you can choose the right one with more confidence.

kennen vs. wissen

kennen and wissen can both mean “to know,” but they do not work the same way.

• kennen = to be familiar with a person, place, thing, or subject
• wissen = to know a fact, piece of information, or answer

Compare these examples:

Kennst du dieses Buch?
Are you familiar with this book?

Nein, aber ich weiß, dass es sehr populär ist.
No, but I know that it is very popular.

A helpful memory cue is to think of kennen as “to be familiar with.” That works well in sentences like these:

Ich kenne deinen Bruder.
I know your brother. I am familiar with him.

Wirklich? Was weißt du über meinen Bruder?
Really? What do you know about my brother?

Mein Vater kennt diese Biene nicht.
My father is not familiar with this bee.

Er weiß jetzt, dass er sie nicht essen sollte.
He now knows that he should not eat it.

wissen can also appear directly with some nouns when the idea is “I know the answer” or “I know the information.”

Ich weiß die Antwort.
I know the answer.

Ich weiß ihre Telefonnummer.
I know her telephone number.

Weißt du den Weg?
Do you know the way?

You will also often see wissen with question words like was, wer, wo, warum, and wie:

Ich weiß, wo er wohnt.
I know where he lives.

Weißt du, wie das funktioniert?
Do you know how that works?

wann vs. wenn vs. als

These are some of the most common German grammar confusion points because English uses “when” for all three ideas.

wann

wann asks about a specific time or introduces indirect questions about time.

Wann warst du zuletzt beim Zahnarzt?
When were you last at the dentist?

Sie hat nicht gesagt, wann sie nach Hause gekommen ist.
She did not say when she came home.

wenn

wenn is used for repeated actions, general time situations, conditions, and hypothetical situations.

Mein Bruder hat immer Bauchschmerzen, wenn er Eis isst.
My brother always has a stomachache when he eats ice cream.

Wenn er von einer Biene gestochen wird, muss er ins Krankenhaus.
If he gets stung by a bee, he has to go to the hospital.

Wenn er mehr Geld hätte, würde ich ihn hübscher finden.
If he had more money, I would find him more handsome.

als

als is the word you want for a single completed event in the past, or for a finished period of time in the past.

Als ich jung war, konnte ich sehr schnell rennen.
When I was young, I could run very fast.

Er war allein zu Hause, als er Schritte im ersten Stock hörte.
He was home alone when he heard footsteps upstairs.

A quick way to remember the difference:

• wann = when? or when exactly?
• wenn = if, whenever, or repeated/general situations
• als = one-time past event or completed past period

seit, vor, and für

This trio causes trouble because English often uses the word “for” in situations where German does something different.

seit

seit describes something that started in the past and is still continuing now. In these sentences, German usually uses the present tense.

Ich arbeite seit vier Jahren hier.
I have worked here for four years.

Ich arbeite seit 2022 hier.
I have worked here since 2022.

Er sitzt seit sechs Stunden im Wohnzimmer und spielt auf seinem Handy.
He has been sitting in the living room and playing on his phone for six hours.

If you want more help with the tense difference between German and English, see my lesson on how to translate 6 German tenses into 12 English tenses.

vor

vor is used for time expressions meaning “ago.”

Ich habe vor einem Monat gekündigt.
I quit a month ago.

vor zwei Tagen
two days ago

vor einer Stunde
an hour ago

vor fünf Jahren
five years ago

Be careful not to confuse vor with bevor. They are related, but they do different jobs.

Vor dem Essen wasche ich meine Hände.
Before the meal, I wash my hands.

Bevor ich esse, wasche ich meine Hände.
Before I eat, I wash my hands.

vor is followed by a noun or pronoun. bevor introduces a whole clause.

für

für can mean “for,” but not every English “for” becomes für in German.

Ich habe drei Stunden gearbeitet.
I worked for three hours.

German often leaves für out when the expression simply states a duration of time.

Ich fahre für drei Wochen nach Deutschland.
I am going to Germany for three weeks.

Wir mieten die Wohnung für ein Jahr.
We are renting the apartment for one year.

Here, für works because the time period is planned or intended. It can also show purpose, benefit, or direction toward someone or something:

Sie arbeitet für McDonald’s.
She works for McDonald’s.

Diese Lektion ist besonders gut für Anfänger.
This lesson is especially good for beginners.

How to keep these words straight

When you run into a confusing German word pair, ask yourself what kind of meaning you need:

• Are you talking about familiarity or information? Use kennen or wissen.
• Are you asking about a time point, a condition, or a one-time past event? Choose wann, wenn, or als.
• Are you talking about a continuing period, something that happened ago, or a planned duration? Check seit, vor, and für.

The more you focus on meaning instead of English translation, the faster these word choices will start to feel natural.

More commonly confused German words to study next

These are only a few examples. German learners run into plenty of other German word pairs and grammar traps, too.

If you want another useful comparison, watch my lesson on bis, bis zum, bis ans, bis auf. It is a great follow-up if you want to keep building your confidence with tricky small words in German.

And if you are ready to keep strengthening your grammar foundation, keep exploring the rest of the lessons on German word choice and sentence structure here at Learn German with Herr Antrim.