Both conocer and saber translate to to know in English, but they are not interchangeable. Each one covers a different type of knowledge. The good news is that the distinction is fairly consistent, so once you learn it, you can apply it across the board.
Conocer: familiarity
Use conocer when you mean to be familiar with or to be acquainted with something or someone. Think of it as experiential knowledge - you've encountered the person, place, or thing before.
People
When conocer takes a person as its object, you need the personal a:
Yo conozco a tu hermana. (I know your sister.)
¿Conoces a Carmen? (Do you know Carmen?)
No conozco a nadie en esta ciudad. (I don't know anybody in this city.)
Places
Conocer is the verb you want when talking about places you have or haven't been to:
Yo no conozco Venecia. (I've never been to Venice.)
¿Conoces Buenos Aires? (Have you been to Buenos Aires?)
Ella conoce muy bien Madrid. (She knows Madrid very well.)
Notice how in English the translation shifts. Conozco Venecia doesn't literally mean I know Venice - it means something closer to I'm familiar with Venice or I've been to Venice.
Things: movies, books, songs, restaurants
You also use conocer for cultural items and things you are familiar with:
¿Conoces la película Casablanca? (Do you know the movie Casablanca?)
No conozco ese restaurante. (I don't know that restaurant.)
¿Conoces las canciones de Rosalía? (Do you know Rosalía's songs?)
Saber: skills and information
Use saber for two things: skills and information.
Skills
When you know how to do something, use saber followed by an infinitive:
Yo sé nadar. (I know how to swim.)
Mi hermana sabe bailar salsa. (My sister knows how to dance salsa.)
¿Sabes tocar el piano? (Do you know how to play the piano?)
Él no sabe cocinar. (He doesn't know how to cook.)
Notice that in Spanish we say sé nadar, not sé cómo nadar. The infinitive goes directly after saber. There is no need for a how equivalent.
Information
When you know a fact or a piece of information, use saber. In most cases, saber will be followed by a subordinate clause introduced by que:
Yo sé que tú tienes dos hermanos. (I know that you have two brothers.)
Ella sabe que nosotros vivimos en Brooklyn. (She knows that we live in Brooklyn.)
¿Sabes que María fue a España? (Do you know that María went to Spain?)
In English, you can drop that - you can say I know you have two brothers. In Spanish, you cannot drop que. You must say Yo sé que tú tienes dos hermanos.
Saber also works with question words like dónde, cuándo, quién, and cómo:
¿Sabes dónde vive Juan? (Do you know where Juan lives?)
No sé cuándo llega el tren. (I don't know when the train arrives.)
Ella no sabe quién es. (She doesn't know who he is.)
A structural shortcut
If you look at the examples above, you'll notice a pattern. Conocer usually takes a direct object - a noun, a person, a place:
Conozco + a María / Madrid / la película
Saber, on the other hand, usually takes a verb (for skills) or a full clause with que (for information):
Sé + nadar / cocinar / bailar
Sé + que ella vive en Madrid / que él es abogado
This structural difference can help you when you're unsure which verb to pick. If what follows is a noun, you probably want conocer. If what follows is a verb or a clause, you probably want saber.
Conjugation in the present tense
Both verbs are irregular in the first person singular (yo).
Conocer: conozco, conoces, conoce, conocemos, conocen
Saber: sé, sabes, sabe, sabemos, saben
The rest of the forms in the present tense are regular for both verbs.
Conocer and saber in the past
In the preterite, conocer and saber behave a little differently than in the present.
Conocer in the preterite usually means to meet someone for the first time:
Conocí a tu hermana ayer. (I met your sister yesterday.)
¿Conociste a Juan el viernes? (Did you meet Juan on Friday?)
Saber in the preterite usually means to find out or to learn a piece of information:
Supe que María se casó. (I found out that María got married.)
¿Cuándo supiste la noticia? (When did you find out the news?)
Conocer is regular in the preterite: conocí, conociste, conoció, conocimos, conocieron. Saber is irregular: supe, supiste, supo, supimos, supieron.
Outside of these past-tense uses, both verbs mostly appear in the present, since they tend to describe ongoing states - people you know, skills you have, facts you're aware of.
Common mistakes
Mixing them up with people
A classic mistake is using saber with people. You cannot say Yo sé a María. People are always conocer:
Yo conozco a María. (I know María.)
Forgetting the personal a
When conocer takes a person as its object, you need the preposition a. Don't forget it:
Conozco a tu primo. (I know your cousin.) - not Conozco tu primo.
Using saber for places
You wouldn't say Yo sé Nueva York. Places go with conocer:
Yo conozco Nueva York. (I know New York.)
Conocer and saber in the same sentence
It's very common to find both verbs in the same sentence:
Conozco a Pedro, y sé que es abogado. (I know Pedro, and I know he's a lawyer.)
No conozco a tu hermano, pero sé que vive en California. (I don't know your brother, but I know he lives in California.)
Sé que ella sabe bailar, pero no la conozco. (I know she knows how to dance, but I don't know her.)
These sentences are a great way to see the contrast in action. Conocer handles the people, saber handles the facts and skills.
Quick reference
Conocer - people, places, things (familiarity):
Conozco a María. (I know María.)
No conozco Tokio. (I've never been to Tokyo.)
¿Conoces este libro? (Do you know this book?)
Saber - skills (+ infinitive) and information (+ que / question word):
Sé nadar. (I know how to swim.)
Sé que ella vive aquí. (I know she lives here.)
No sé dónde está. (I don't know where it is.)
For a deeper dive into how direct objects interact with these verbs, as well as the role of the personal a with conocer, check our guides on those topics. The RAE dictionary is also a useful resource if you want to explore additional meanings and idiomatic uses of conocer and saber.