How to Say 'I Know' in Spanish: Sé, Lo Sé, and Conozco

To say “I know” in Spanish, use lo sé /lo ˈse/ when replying to information, sé /se/ before a fact or skill, and conozco /koˈnosko/ when you know a person, place, or thing through experience. The distinction matters: saying the wrong one is understandable, but it immediately sounds translated from English.

Spanish is spoken by more than 600 million potential speakers worldwide, according to the Instituto Cervantes, and it is an official language in 20 sovereign countries. Across those regions, the difference between saber /saˈβeɾ/ and conocer /konoˈseɾ/ remains one of the most useful early grammar distinctions.

If you are still building your first conversation phrases, start with how to say hello in Spanish, then add these natural ways to show that you understand or already have the information.

The three core choices

English uses “know” for several ideas. Spanish separates them more clearly, especially between knowing information and being familiar with someone or something.

The first question to ask yourself is simple: are you talking about a fact, a skill, a person, or a place?

Sé

Sé /se/ is the first-person form of saber /saˈβeɾ/. Use it for facts, information, answers, and abilities.

It usually appears before what you know. For example, sé que tienes razón /se ke ˈtjenes raˈson/ means “I know that you are right,” while sé nadar /se naˈðaɾ/ means “I know how to swim.”

You can use sé /se/ with question words too:

• Sé dónde está. /se ˈdonde esˈta/ , I know where it is.
• Sé quién fue. /se kjen ˈfwe/ , I know who it was.
• Sé cómo hacerlo. /se ˈkomo aˈseɾlo/ , I know how to do it.
• Sé la respuesta. /se la resˈpwesta/ , I know the answer.

The Real Academia Española and the Asociación de Academias de la Lengua Española describe saber /saˈβeɾ/ as the verb for knowledge acquired as information, including practical know-how. That is why sé cocinar /se kosiˈnaɾ/, “I know how to cook,” is correct.

Lo sé

Lo sé /lo ˈse/ literally means “I know it,” but English speakers should treat it as the standard complete answer to “I know.” The small word lo /lo/ refers to an idea, statement, fact, or situation already clear in the conversation.

If someone says mañana tenemos examen /maˈɲana teˈnemos ekˈsamen/, “we have a test tomorrow,” you can simply answer lo sé /lo ˈse/. You do not need to repeat the whole fact.

Do not confuse lo sé /lo ˈse/ with sé /se/. Both are correct, but they work differently:

In fast speech, Spanish speakers often make lo sé /lo ˈse/ sound like one compact unit. Listen for it in dialogue-heavy shows, then repeat the full rhythm rather than stressing each word separately.

Conozco

Conozco /koˈnosko/ is the first-person form of conocer /konoˈseɾ/. Use it when you know people, places, neighborhoods, books, films, musicians, or subjects because you have encountered them.

For example, conozco a Laura /koˈnosko a ˈlawɾa/ means “I know Laura,” while conozco Barcelona /koˈnosko βaɾseˈlona/ means “I know Barcelona” in the sense that you have been there or are familiar with it.

A useful contrast is sé de Madrid /se ðe maˈðɾið/ versus conozco Madrid /koˈnosko maˈðɾið/. The first means you know about Madrid, perhaps through reading or news. The second means you know the city itself, perhaps because you have visited or lived there.

Francisco Moreno Fernández, in Variedades de la lengua española, emphasizes that Spanish changes across regions in pronunciation and vocabulary, but this core semantic difference is stable. Whether you hear Spanish from Mexico, Colombia, Argentina, or Spain, use conocer /konoˈseɾ/ for familiarity and saber /saˈβeɾ/ for information.

Natural phrases you will hear often

Ya sé

Ya sé /ʝa ˈse/ means “I know already.” It is extremely common, especially when someone has just told you something you already heard.

A softer version is sí, ya sé /si ʝa ˈse/ or sí, lo sé /si lo ˈse/. If you want to acknowledge information politely without sounding annoyed, add gracias /ˈɡɾasjas/ or a short explanation: sí, lo sé, gracias por avisarme /si lo ˈse ˈɡɾasjas poɾ aβiˈsaɾme/.

No sé

No sé /no ˈse/ means “I do not know.” It is one of the highest-value phrases for any learner because it works alone and with nearly any follow-up.

You can say no sé /no ˈse/ when you have no answer, no sé dónde está /no se ˈdonde esˈta/ when you do not know where something is, or no sé qué hacer /no se ke aˈseɾ/ when you do not know what to do.

For “I do not understand,” use no entiendo /no enˈtjendo/, not no sé /no ˈse/. The first says you cannot follow what someone means; the second says you lack the answer or information. If that distinction feels difficult, see our guide to Spanish question words, since they pair naturally with both expressions.

Me suena

Me suena /me ˈswena/ literally means “it sounds to me,” but it often means “that rings a bell.” Use it when something feels familiar but you are not fully certain.

For example, ese nombre me suena /ˈese ˈnombre me ˈswena/ means “that name sounds familiar.” It is more honest and natural than claiming lo sé /lo ˈse/ when your memory is incomplete.

Tengo entendido que

Tengo entendido que /ˈteŋɡo entenˈdiðo ke/ means “my understanding is that” or “I have heard that.” It is useful when you want to state information carefully rather than claim direct certainty.

You may hear it in workplace conversations, travel planning, news discussions, and polite disagreements. For example, tengo entendido que cierran a las seis /ˈteŋɡo entenˈdiðo ke ˈsjerran a las ˈsejs/ means “my understanding is that they close at six.”

Tone, emphasis, and the word yo

Spanish verb endings usually reveal the subject, so yo sé /ʝo ˈse/ is grammatically correct but not always necessary. Most of the time, simply say sé /se/ or lo sé /lo ˈse/.

Add yo /ʝo/ when contrasting yourself with another person:

• Yo sé la verdad, pero él no. /ʝo se la βeɾˈðað ˈpeɾo el no/
• Yo conozco ese restaurante. /ʝo koˈnosko ˈese resta.uˈɾante/

This emphasis can sound confident, defensive, or even dramatic depending on context. Spanish-language television makes this easy to hear: actors often add the pronoun when the emotional point is “I know, unlike you.”

José Ignacio Hualde’s work on Spanish sound patterns is especially useful here. Spanish stress is predictable in many forms, and the acute accent in sé /se/ marks both stress and meaning. Without the accent, se /se/ is a different grammatical word, commonly used in reflexive and impersonal structures.

Common mistakes English speakers make

Using saber for people

Do not say sé a María /se a maˈɾia/ for “I know María.” Use conozco a María /koˈnosko a maˈɾia/.

When the person is a direct object, Spanish usually requires the personal a /a/. That is why conozco a María /koˈnosko a maˈɾia/ includes it, while conozco Madrid /koˈnosko maˈðɾið/ does not.

Using conocer for facts

Do not say conozco que llega tarde /koˈnosko ke ˈʝeɣa ˈtaɾðe/. Use sé que llega tarde /se ke ˈʝeɣa ˈtaɾðe/ because you are talking about information.

Think of conocer /konoˈseɾ/ as familiarity built from contact. Think of saber /saˈβeɾ/ as knowledge you can state, answer, or perform.

Treating ya sé as always polite

Ya sé /ʝa ˈse/ is not automatically rude, but it can sound dismissive after repeated reminders. When in doubt, choose sí, lo sé /si lo ˈse/ or gracias, ya lo sabía /ˈɡɾasjas ʝa lo saˈβia/ if you want a gentler tone.

Practice with real responses

Try matching the reply to the situation before checking the answer.

Someone says: Tu amiga vive en Chile. /tu aˈmiɣa ˈbiβe en ˈtʃile/
Reply: Lo sé. /lo ˈse/

Someone asks: ¿Sabes bailar salsa? /ˈsaβes bajˈlaɾ ˈsalsa/
Reply: Sí, sé bailar un poco. /si se bajˈlaɾ um ˈpoko/

Someone asks: ¿Conoces a mi hermano? /koˈnoses a mi eɾˈmano/
Reply: No, no lo conozco. /no no lo koˈnosko/

Someone mentions a restaurant you vaguely recognize.
Reply: Me suena, pero no lo conozco. /me ˈswena ˈpeɾo no lo koˈnosko/

These short exchanges are exactly the kind of lines worth learning from scenes. Watch a clip once with subtitles, replay it, then say the response before the actor does. That practice connects grammar with timing, facial expression, and tone.

The key rule to remember

Use lo sé /lo ˈse/ for “I know” as a complete response. Use sé /se/ for facts and abilities, and use conozco /koˈnosko/ for familiarity with people, places, and things.

Once you can make that three-way choice automatically, your Spanish will sound far more natural. Build on it with phrases for relationships in how to say I love you in Spanish, and learn natural departures with how to say goodbye in Spanish.