Wissen vs kennen
The short answer
Wissen is for facts and information, and it is what takes a dass, ob or wo clause: ich weiß, dass er kommt. Kennen is for familiarity with a person, place or thing, and it always needs a direct object: ich kenne ihn. If a clause follows, the verb is wissen.
At a glance
Wissen or Kennen?
| Compare | WissenFacts and clauses. Information. | KennenFamiliarity. Always with an object. |
|---|---|---|
| What can follow | dass, ob, wo, wer, wie + clause | An accusative object only |
| People | Only ich weiß, wer er ist | Ich kenne ihn |
| Places | Ich weiß, wo es ist | Ich kenne Berlin |
| Can it stand alone? | Yes: ich weiß. | No: needs an object |
| Conjugation | Irregular: ich weiß, du weißt, er weiß | Regular: ich kenne, du kennst |
| Past | wusste | kannte |
How to choose
Ask these, in order
- 1
Is a clause coming, dass, ob, wo, wer, warum, wie?
Wissen. Kennen cannot take one.
Ich weiß, dass sie morgen kommt.
I know she’s coming tomorrow.
- 2
Is it a person, a city, a film or a song?
Kennen, with the object in the accusative.
Kennst du diesen Film?
Do you know this film?
- 3
Can the sentence end right after the verb?
Wissen. Ich weiß is complete; ich kenne is not.
Der Zug fällt aus. Ich weiß.
The train’s cancelled. I know.
- 4
Is it a piece of information you could state?
Wissen, even with a noun object.
Weißt du seine Telefonnummer?
Do you know his phone number?
NBA fact you could read out, so wissen, despite the noun.
Side by side
Each one, in full
When to use wissen
Facts and clauses. Information.
Wissen handles information, and it is the verb that takes subordinate clauses. Ich weiß, dass…, ich weiß nicht, ob…, weißt du, wo…? Note the comma before the clause, which German requires and English does not.
It is irregular in the singular: ich weiß, du weißt, er weiß, with no -e on the ich form, which makes it look like a modal verb. The plural is regular: wir wissen, ihr wisst, sie wissen.
Ich weiß nicht, ob das stimmt.
I don’t know whether that’s right.
Weißt du, wie spät es ist?
Do you know what time it is?
Das habe ich nicht gewusst.
I didn’t know that.
When to use kennen
Familiarity. Always with an object.
Kennen is acquaintance through exposure and always takes a direct object in the accusative: ich kenne den Weg, kennst du sie? Without an object it cannot stand at all.
It also covers familiarity with a subject rather than mastery of it: er kennt sich mit Autos aus uses the separable sich auskennen and means he knows his way around cars, a common and useful extension.
Ich kenne diese Gegend gut.
I know this area well.
Wir kennen uns seit der Schule.
We’ve known each other since school.
Kennst du das Gefühl?
Do you know that feeling?
Mistakes to avoid
What learners actually get wrong
Ich kenne, dass er recht hat.
Ich weiß, dass er recht hat.
Kennen cannot take a clause. As soon as dass, ob or a question word appears, the verb must be wissen, the same structural test that separates savoir from connaître and saber from conocer.
Ich weiß Berlin.
Ich kenne Berlin.
A place you have been to is familiarity. Ich weiß, wo Berlin ist is correct, because that converts it into information and adds the clause that wissen requires.
Ich weiße nicht.
Ich weiß nicht.
Wissen is irregular and the ich form takes no -e. It patterns with the modal verbs here, which is why it looks wrong to learners who have just practiced regular endings.
Ich weiß dass er kommt.
Ich weiß, dass er kommt.
German puts a comma before a subordinate clause, always. It is not optional the way it often is in English, and its absence is one of the most visible errors in written German.
Questions
Asked and answered
- What about können?
- Können is ability, not knowledge: ich kann schwimmen, I can swim. Where French and Spanish use savoir and saber for skills, German uses können, so the three-way split is wissen for facts, kennen for familiarity, können for skills.
- Why does wissen conjugate like a modal?
- Because historically it is a preterite-present verb, the same class the modals come from. That is why ich weiß has no ending and the vowel changes in the singular. Knowing the reason will not change the forms, but it does explain why they look so odd.
- Does the same split exist in other languages?
- Yes, French savoir and connaître, Spanish saber and conocer, and the same clause test works in all three. If you have studied one, German only adds können for skills and the comma rule before clauses.