nicht vs. kein. Two ways to say "no."
English "not" does two completely different jobs. It can turn "a car" into "no car", and it can turn "I am tired" into "I am not tired". German never lets one word handle both. kein takes the first job. nicht takes the second. Mixing them up is one of the first habits English speakers have to unlearn.
The first question: is there a noun being switched off?
If the English sentence could be rephrased as "no ___" with a noun in the gap, that's a job for kein. Everything else, verbs, adjectives, adverbs, whole sentences, belongs to nicht.
| English | German | Why |
|---|---|---|
| I don't have a car. | Ich habekeinenWagen. | "a car" → "no car", a noun |
| I don't have time. | Ich habekeineZeit. | "time" → "no time", a noun |
| I'm not tired. | Ich bin nicht müde. | negates the adjective "tired" |
| I don't smoke. | Ich rauche nicht. | negates the whole sentence |
| That's not my book. | Das ist nicht mein Buch. | "mein Buch" already has an article, so kein can't step in |
That last row is the key. kein can only appear where ein, eine, or no article at all would otherwise stand. The moment a noun already carries der, die, das, mein, dieser, or any other article, kein has nowhere to go, and nicht takes over.
kein replaces ein, eine, or nothing at all
Think of kein as the negative twin of ein and eine. Wherever those would stand, or wherever a plural or uncountable noun would normally stand with no article at all, kein simply takes that spot.
| Positive | Negative with kein | Pattern |
|---|---|---|
| ein Auto | keinAuto | ein → kein |
| eine Idee | keineIdee | eine → keine |
| Zeit | keineZeit | no article → keine |
| Geschwister | keineGeschwister | no article (plural) → keine |
kein declines exactly the way ein does, with the same six endings across the four cases, plus the one form ein never gets: the plural keine. Ich sehekeinenHund. Er hilftkeinerFrau. The full table of every ending is in the article on ein, eine, kein linked below.
nicht: everything that isn't a bare noun
nicht handles the rest: verbs, adjectives, adverbs, prepositional phrases, and any noun that already has its own article.
| What's being negated | Example |
|---|---|
| The whole sentence | Ich verstehedas nicht. |
| An adjective | DasWetter ist nicht schön. |
| An adverb | Sie kommt nicht oft. |
| A prepositional phrase | Wir wohnen nicht in Berlin. |
| A noun with der, die, das, or mein | Das ist nicht der richtige Weg. |
The quick test: can the English sentence be rewritten as "no ___" with a noun, and would that noun normally take ein, eine, or no article at all? If yes, use kein. If the noun already has an article, or there's no noun to switch off in the first place, use nicht.
Where nicht goes
kein is easy to place: it sits exactly where ein or eine would, right in front of its noun. nicht is trickier, because its position changes depending on what it's negating.
| Sentence | What's negated | Where nicht goes |
|---|---|---|
| Ich arbeite heute nicht. | the whole sentence | at the end |
| Ich rufedich nicht an. | the whole sentence (separable verb) | right before the separable prefix |
| Ich habe dasBuch nicht gelesen. | the whole sentence (perfect tense) | right before the past participle |
| Er wohnt nicht in Berlin, sondern in München. | just "in Berlin" | directly before that phrase |
The pattern behind all four rows is the same. When nicht negates the sentence as a whole, it drifts toward whatever sits at the very end of the clause, the second verb part, the separable prefix, the participle, or, if none of those exist, the end of the sentence itself. When nicht singles out one specific word or phrase, it plants itself directly in front of that word or phrase, no matter where that lands.
One word, one noun, with ein, eine, or no article at all? kein steps into that exact spot, and brings a plural of its own → keine.
Anything else, an adjective, an adverb, a phrase, a whole sentence, or a noun that already has an article? nicht, placed right before the thing it negates, or pulled to the end when it negates everything.
For the full declension of kein, side by side with ein and eine: ein, eine, kein. The indefinite articles. For how to answer a negative question with "yes, actually": doch. The word English simply doesn't have.