Early on, every German learner hits a moment where they want to say "I know" and reach for a word — and whatever they pick, it's a fifty-fifty shot at being wrong. The problem isn't the vocabulary. It's that English uses one verb, "to know," for two genuinely different things that German keeps separate on principle.
Get the distinction right and both verbs click into place immediately. Get it wrong and you'll be saying things like "I know Berlin" when you mean you know the city, and accidentally implying you know the city as a piece of trivia rather than a place you've spent time in. The difference matters.
Why German Splits 'To Know' Into Two Verbs
German distinguishes between two fundamentally different kinds of knowing:
Knowing through personal acquaintance or experience — you've met someone, been somewhere, encountered something firsthand. This is relational knowledge. You know a person, a place, a film, a feeling.
Knowing a fact — you have a piece of information in your head. You know an answer, a date, a name, a reason, a rule. This is propositional knowledge — something that could in principle be true or false.
German has a dedicated verb for each. Kennen for the first. Wissen for the second. They are not substitutes for each other — using one where the other belongs is a clear grammatical error, not a style choice.
Kennen — Knowing Through Familiarity
Kennen expresses personal acquaintance — knowing someone or something because you have direct experience of it. It always takes a direct object: a person, a place, a thing, a work of art, a concept you've personally encountered.
Ich kenne Maria.
I know Maria. (I've met her, we're acquainted)
Kennst du Berlin?
Do you know Berlin? (have you been there, are you familiar with it)
Ich kenne dieses Lied.
I know this song. (I've heard it, I'm familiar with it)
Er kennt das Gefühl.
He knows the feeling. (he's experienced it)
Wir kennen uns schon lange.
We've known each other for a long time.
Kennst du einen guten Arzt?
Do you know a good doctor? (personally, someone you can recommend)
Kennen is a regular verb. It conjugates without surprises: ich kenne, du kennst, er/sie/es kennt, wir kennen, ihr kennt, sie/Sie kennen.
Wissen — Knowing a Fact
Wissen expresses factual knowledge — having a piece of information. It answers questions like: what, where, when, why, how, whether. What follows wissen is typically a fact, an answer, or a subordinate clause containing information.
Ich weiß die Antwort.
I know the answer. (the information)
Weißt du, wie spät es ist?
Do you know what time it is?
Er weiß, wo sie wohnt.
He knows where she lives.
Ich weiß nicht, warum er das getan hat.
I don't know why he did that.
Weißt du seinen Namen?
Do you know his name? (the piece of information — his name)
Sie weiß alles über das Thema.
She knows everything about the topic.
The One-Question Test
Before choosing between kennen and wissen, ask: is what you know a fact, or a person/place/thing you have experience of?
Fact → wissen. Person, place, or thing you're personally familiar with → kennen.
A useful way to feel the difference: kennen can usually be replaced with "be familiar with" or "have experience of." Wissen can usually be replaced with "have the information that" or "be aware of the fact that."
Ich kenne seinen Namen. ✗ (you're not personally acquainted with the name)
Ich weiß seinen Namen. ✓ (you have the information — his name)
Ich weiß Maria. ✗ (Maria is a person, not a fact)
Ich kenne Maria. ✓ (you're acquainted with her)
Kennst du, wo der Bahnhof ist? ✗
Weißt du, wo der Bahnhof ist? ✓ (location = a piece of information)
Wissen Conjugation — It's Irregular
Wissen behaves like a modal verb in the present tense — singular forms are irregular:
| Person | Present | Simple past |
|---|---|---|
| ich | weiß | wusste |
| du | weißt | wusstest |
| er/sie/es | weiß | wusste |
| wir | wissen | wussten |
| ihr | wisst | wusstet |
| sie/Sie | wissen | wussten |
The forms ich weiß and er weiß trip up beginners who expect ich wisse or ich wissen. The past tense wusste is regular from that point forward. The Konjunktiv II form is wüsste — useful and common: Ich wüsste gerne, ob... (I'd like to know whether...).
Wissen With Subordinate Clauses
One of the most common patterns for wissen is with a dependent clause introduced by ob, dass, wo, wann, wie, warum, wer, etc. Kennen cannot be used this way — it always needs a direct noun object.
Ich weiß, dass er kommt.
I know that he's coming.
Weißt du, ob sie verheiratet ist?
Do you know if she's married?
Ich weiß nicht, wann der Zug abfährt.
I don't know when the train leaves.
Er weiß, wie man das macht.
He knows how to do that.
Whenever "to know" is followed by a that/if/whether/when/where/how/why clause in English, the German is always wissen — never kennen. This is one of the clearest structural signals for choosing between the two.
Edge Cases Worth Knowing
Knowing someone's name
A name is a piece of information — wissen. But knowing a person is familiarity — kennen. These are different questions.
Ich kenne ihn, aber ich weiß seinen Namen nicht.
I know him, but I don't know his name.
Knowing a city
Knowing a city as a place you've been → kennen. Knowing where a city is, or a fact about it → wissen.
Ich kenne Hamburg gut. (I know Hamburg well — I've spent time there)
Ich weiß, dass Hamburg an der Elbe liegt. (I know the fact that it's on the Elbe)
Knowing a word
A word is a piece of information — wissen for the meaning or spelling, kennen if you're familiar with the word as something you've encountered.
Kennst du das Wort "Fingerspitzengefühl"? (are you familiar with this word?)
Weißt du, was "Fingerspitzengefühl" bedeutet? (do you know what it means?)
Both are valid — they're asking slightly different questions. The first asks if you've encountered the word. The second asks for the definition.
Common Traps
Trap 1 — Using kennen before a subordinate clause
Weißt du, wo er wohnt? ✓
Kennst du, wo er wohnt? ✗ (kennen cannot introduce a clause)
Trap 2 — Using wissen for people
Ich kenne den Bürgermeister. ✓
Ich weiß den Bürgermeister. ✗
Trap 3 — Forgetting weiß (not wisse or wissen for ich/er)
Ich weiß es nicht. ✓
Ich wissen es nicht. ✗
Ich wisse es nicht. ✗ (Konjunktiv I — only in indirect speech)
Trap 4 — "I know!" as an exclamation
In English, "I know!" as a response to someone saying something obvious uses "know" as factual acknowledgment — so German uses wissen:
"Du musst mehr schlafen." — "Ich weiß!"
"You need to sleep more." — "I know!"
Quick Recap
- German has two verbs for "to know" because it distinguishes two different kinds of knowing.
- Kennen — personal familiarity, acquaintance, experience. Use it for people, places, and things you know firsthand. Always takes a direct noun object.
- Wissen — factual knowledge, information. Use it for facts, answers, and clauses beginning with ob, dass, wo, wann, wie, warum. Can take a noun object (a fact) or a subordinate clause.
- The test: can you replace "know" with "be familiar with"? → kennen. Can you replace it with "have the information that"? → wissen.
- Kennen can never introduce a subordinate clause. Wissen can introduce one and often does.
- Wissen is irregular in the present singular: ich weiß, du weißt, er/sie/es weiß.
- "I know!" as an exclamation = Ich weiß! — always wissen, never kennen.