English gets by with a single verb, "know," for three completely different ideas: knowing a fact, being acquainted with someone or something, and knowing how to do something. German splits these across wissen, kennen, and können, and choosing wrongly is one of the most recognizable learner mistakes. The reassuring part: the grammar of the sentence — what comes after the verb — tells you which one you need.
The core split: facts vs acquaintance
wissen = to know a fact or piece of information. It is almost always followed by a dass-clause, an indirect question (ob, wo, wann, warum…), or a neutral object like es, das, or die Antwort.
kennen = to be acquainted or familiar with a person, a place, or a thing. It takes a plain direct (accusative) object — a noun — and never a clause.
Compare the two. With a fact expressed as a clause, you must use wissen:
Ich weiß, dass er morgen kommt.
I know that he's coming tomorrow.
Weißt du, wo der Bahnhof ist?
Do you know where the station is?
With a person, place, or thing as a direct object, you must use kennen:
Ich kenne ihn schon seit Jahren.
I've known him for years.
Kennst du München gut?
Do you know Munich well?
This division mirrors Romance languages exactly — Spanish saber (facts) vs conocer (acquaintance), French savoir vs connaître. English is the odd one out for merging them.
wissen: irregular and clause-loving
wissen is irregular in the present singular — it looks almost like a modal verb, with a vowel change and no -t ending in the third person:
| Person | Präsens | Präteritum |
|---|---|---|
| ich | weiß | wusste |
| du | weißt | wusstest |
| er/sie/es | weiß | wusste |
| wir | wissen | wussten |
| ihr | wisst | wusstet |
| sie/Sie | wissen | wussten |
The Partizip II is gewusst (Ich habe es nicht gewusst). Note the ß in weiß and weißt, and the double-s in wusste/gewusst — these are spelling traps, since weiß also means "white."
Besides clauses, wissen pairs with the lightweight neutral pronouns es and das, which stand in for an unspoken fact:
Ich weiß es nicht — frag mal die Chefin.
I don't know — ask the boss.
Niemand wusste die Antwort auf seine Frage.
Nobody knew the answer to his question.
That last one shows the rare case where wissen takes a concrete-looking object, die Antwort. But notice it's still information — an answer is a fact. You'd never say wissen about a person.
kennen: regular and object-loving
kennen is a regular (weak) verb: kennen / kannte / gekannt. It always needs a noun in the accusative — someone or something you've encountered:
Diesen Film kenne ich noch nicht.
I don't know this movie yet.
Wir kannten uns schon aus der Schulzeit.
We already knew each other from our school days.
A useful test: if you could replace the object with "I'm familiar with " or "I'm acquainted with " in English, it's kennen. You can be acquainted with a song, a recipe, a neighborhood — all kennen. You cannot be "acquainted with that he's coming," which is why clauses force wissen.
The third sibling: können for skills
When "know" means know how to do something — a skill, an ability, or a language — German uses the modal können, not wissen or kennen:
Sie kann gut Klavier spielen.
She knows how to play the piano well.
Ich kann ein bisschen Deutsch.
I know a little German.
That second sentence has no other verb at all — with a language as the object, können stands alone, much like English "I can speak German" shortened to "I know German." Using wissen or kennen here would be wrong.
Decision flowchart
| What follows "know"? | Verb | Example |
|---|---|---|
| a fact: dass-/ob-/w-clause, or es/das | wissen | Ich weiß, dass… |
| a person, place, or thing (noun object) | kennen | Ich kenne sie / Berlin |
| a skill, ability, or language | können | Ich kann schwimmen / Deutsch |
Common Mistakes
The number-one error is using kennen with a clause, because English allows "I know that…":
❌ Ich kenne, dass er Recht hat.
Incorrect — kennen cannot take a clause; facts need wissen.
✅ Ich weiß, dass er Recht hat.
I know that he's right.
The mirror-image error is using wissen with a person, calquing "I know him":
❌ Ich weiß ihn aus der Arbeit.
Incorrect — a person you're acquainted with needs kennen.
✅ Ich kenne ihn aus der Arbeit.
I know him from work.
A third trap is using wissen or kennen for a skill or language:
❌ Ich weiß Deutsch.
Incorrect — knowing a language is a skill; use können.
✅ Ich kann Deutsch.
I know German.
A fourth, subtler mistake: regularizing wissen as wisse in the third person singular, forgetting it's irregular:
❌ Er wisst nicht, wo es ist.
Incorrect — third person singular is weiß, not wisst.
✅ Er weiß nicht, wo es ist.
He doesn't know where it is.
Finally, watch the spelling of the past tense — it's wusste (double s), not wußte (the pre-reform spelling) or wisste:
❌ Ich wisste die Antwort nicht.
Incorrect — the Präteritum stem is wuss-.
✅ Ich wusste die Antwort nicht.
I didn't know the answer.
Key Takeaways
- wissen = know a fact; it takes a clause (dass/ob/w-) or es/das. It's irregular: ich weiß, du weißt, er weiß; Präteritum wusste; Partizip gewusst.
- kennen = be acquainted with a person, place, or thing; it takes a direct object and never a clause. Regular: kennen / kannte / gekannt.
- können = know how to do something or know a language (a skill).
- The complement type decides everything: clause → wissen, noun object → kennen, skill/language → können.
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Start learning German→Related Topics
- wissen: Full Conjugation and UsageA2 — Complete conjugation of wissen 'to know (facts)' across every tense and mood, including its modal-like irregular present (weiß/weißt/weiß), the wusste/wüsste forms, the crucial contrast with kennen, and the errors English speakers make.
- kennen: Full Conjugation and UsageA2 — Complete conjugation of kennen 'to know / be acquainted with', a mixed verb, with its accusative valency, the kennen vs. wissen vs. können distinction, and the errors English speakers make.
- können: Ability, Possibility, PermissionA2 — The full conjugation and meanings of können — ability, possibility and informal permission — plus the könnte / konnte trap that turns on a single umlaut.
- kennen vs wissen vs können (to know)B1 — English 'know' splits three ways in German: kennen for acquaintance, wissen for facts, and können for learned skills and languages.
- dass-Clauses and Complement ClausesB1 — A dass-clause is a subordinate clause that serves as the object of a verb of saying, thinking, or feeling — verb-final, comma before dass — alongside the ob-clause for indirect yes/no questions and the dass-less V2 variant of casual speech.
- können: Full Conjugation and UsageA2 — Complete conjugation of the modal verb können 'can / to be able' across every tense and mood, with the double-infinitive Perfekt, the polite könnte, and the errors English speakers make.