savoir vs connaître
Summary
Both translate as "to know," but savoir is for facts, information and knowing how to do something (and takes a clause or an infinitive), while connaître is for being familiar with a person, place or thing (and takes a direct noun).
Explanation
English collapses two ideas into one verb, "to know", that French keeps apart. Savoir is knowledge of facts, information, or how to do something. It introduces a clause with que, si, où, pourquoi, comment (je sais qu'il est parti, je sais où elle habite) or an infinitive meaning "to know how to" (je sais nager, elle sait conduire). It can also stand alone for a known fact: Tu le sais bien.
Connaître is acquaintance or familiarity, and it is always followed directly by a noun — a person, a place, a work, a field: je connais ta sœur, je connais Paris, je connais ce film, il connaît bien la cuisine italienne. Crucially, connaître can NEVER introduce a clause (no connaître que…) and NEVER take an infinitive (no connaître nager). If a que-clause or an infinitive follows, the verb must be savoir.
The contrast is sharpest when the same English sentence could go either way in feeling. Je connais cette chanson means "I'm familiar with this song" (I recognise it, I've heard it); Je sais cette chanson means "I know this song (by heart)", i.e. I can produce it. Likewise je connais la réponse leans on familiarity with a known answer, while je sais la réponse stresses possessing the fact.
Watch the forms, since both are irregular Group 3 verbs. Savoir: je sais, tu sais, il sait, nous savons, vous savez, ils savent; past participle su. Connaître: je connais, tu connais, il connaît, nous connaissons, vous connaissez, ils connaissent; past participle connu (note the circumflex on the î before t). Their similar present-tense singulars (je sais / je connais) are part of why learners mix them up.
Decision rule: look at what follows the verb. A clause (que/si/où…) or an infinitive → savoir; a bare noun naming a person, place or thing you are familiar with → connaître. Quick test: if English allows "know how to" or "know that", use savoir; if it means "be acquainted/familiar with", use connaître.
Examples
Je sais où elle habite. — I know where she lives. (Savoir + clause (où…): a fact.)
Je connais bien ce quartier. — I know this neighbourhood well. (Connaître + noun: familiarity with a place.)
Elle sait nager depuis l'âge de cinq ans. — She has known how to swim since she was five. (Savoir + infinitive = 'know how to'; connaître is impossible here.)
Tu connais ce film ? — Do you know this film? (Connaître + noun: are you familiar with it?)
Je connais cette chanson, mais je ne la sais pas par cœur. — I know this song, but I don't know it by heart. (Minimal pair: connaître = be familiar with; savoir = have it down (a skill/fact).)
Nous savons que le train est en retard. — We know that the train is late. (Savoir + que-clause: a piece of information.)
Common mistakes
Je connais nager.
Je sais nager.
To say "to know how to" do something, French uses savoir + infinitive: « je sais nager » (I can/know how to swim). Connaître never takes an infinitive or a clause; it is followed directly by a noun (a person, a place, a thing): « je connais Paris ». The decision rule: a skill or fact -> savoir; familiarity with a noun -> connaître.
Prerequisites
Related rules
verbsconfusablescore-verbs