“I Do Not Know” In Spanish (& other phrases when you’re not sure)

You’re taking a stroll in a little Spanish town when someone stops you and asks for the time. You don’t have your watch and your phone is dead, so how do you tell them that you don’t know without gesturing animatedly at your bare wrist?

Learning how to say “I don’t know” in Spanish can get you through a lot of conversations. It’s a useful phrase to have in your arsenal and one that you can pull out when you’re not sure about the answer, topic, or even what’s being said.

With that in mind, let’s look at how to say “I don’t know” in Spanish while also looking at some other words and phrases to help you when you’re not sure.

How Do You Say, “I Do Not Know” in Spanish?

As is usually the case, there are several ways to say “I don’t know” in Spanish. It really depends on the context.

No lo sé is the most common expression and the most direct translation. You may also hear it said as yo no sé or even just no sé.

All of these expressions mean the same thing. Yo is the equivalent of “it”, and refers to the thing that is not known. It’s the same as saying “I don’t know it” as opposed to “I don’t know”, though it’s much more common to omit the “it” in English than it is in Spanish.

How to Conjugate No Lo Sé in Spanish

No lo sé means “I don’t know”, so you’ll need to change the pronoun if you’re saying “you/we/I/they”. must also change along with the subject of the sentence:

  • él no lo sabe = he doesn’t know
  • élla no lo sabe = she doesn’t know
  • nosotras no lo sabemos = we don’t know (feminine)
  • nosotros no lo sabemos = we don’t know (masculine)
  • ellas no saben = they don’t know (feminine)
  • ellos no saben = they don’t know (masculine)

If you want to say it in the context of “I am not familiar with it”, use no conozco.

When To Use No Sé

“I don’t know” is one of those phrases that you say more than any other when you’re learning a new language. It’s up there with “do you speak English?”, which is usually said with a defeated sigh after you convince yourself you’re going to try and speak the language but then lose confidence.

How you use it will obviously depend on what you say.

If you’re trying to tell someone that you didn’t understand what they just said, this is not the best phrase to use.

They might get the gist if you say it with a meek smile and a shrug, but the fact that you said those words in Spanish will just confuse matters.

In such cases, you can try one of the following expressions:

  • No tengo idea de lo que estás diciendo –I have no idea what you’re saying.
  • No tendo idea de qué pasó – I have no idea what happened.
  • No entiendo nada de lo que dices –I don’t understand anything you’re saying.
  • ¿Puedes repetirlo? – A very useful phrase as it means “can you repeat it?”

If the person you’re talking to speaks another language, they may understand your struggle and speak more slowly. They may also use simpler words to help you understand. If they only speak Spanish, there’s a good chance they’ll just repeat what they said word-for-word and at the exact same speed.

When that happens, try saying No te comprendo. It means “I can’t understand you” and is a pretty definitive statement, letting the other person know that their efforts are getting nowhere.

Finish by telling them that you’re sorry

  • Lo siento – I’m sorry

How to Say No Idea in Spanish

You’ve added quite a lot of new vocabulary to your list, but there’s room for one more. And it’s the easiest one yet:

  • Ni idea

Pronounced “nee” “eye-DAY-ah”, this simply means “no idea”.

It’s an informal expression that you can use around friends. Think of it in the same context as the English phrase.

If your boss asks you what happened yesterday when you weren’t at the office, you’re not going to simply shrug and casually state, “no idea”.

But if a friend asks you what you’ll do on the weekend and you haven’t thought that far ahead, it’s a good expression to have.

  • Ni idea – no idea

If you have a strong Scottish accent, the pronunciation will come easily. For everyone else, remember it’s “nee” (as in “the knights who say…”), and while “idea” looks the same as in English, it’s pronounced with a “day” and not a “deer”.

If you want something a little more formal to say to your boss, use no tengo certeza, which means “I am not certain” or rather “I don’t have a certainty”.

  • No tengo certeza– I am not certain

Useful Sentences when You’re Learning Spanish and Don’t Know What’s Being Said

If you have limited knowledge of Spanish and find yourself stuck in a conversation with a native speaker, the following phrases are useful to know:

  • No sé la respuesta – I don’t know the answer
  • No te estoy siguiendoI’m not following you
  • No estoy segura de qué hablas I’m not sure what you’re talking about
  • No estoy seguro I’m not sure
  • Otra vez again (as in, please say it again)

Etymology Check

The verb saber means “to know” in Spanish. It comes from the Latin word “sapere”.

“Sapere” also gives us the adjective “sage” (meaning wise and shrewd), which entered the English language via French.

Based on that evidence alone, you’d be forgiven for thinking that “sapere” referred to knowledge and wisdom. But it actually referred to taste.

The connection stems from the use of this word to refer to people who had “good taste” and were wise.

Incidentally, the herb “sage” has a completely different etymology.

Sage (Salvia officinalis) takes its name from the Latin “salvia/salvus”, which meant “healthy”. It was so-named because of the apparent healing properties of this herb.