My teachers says that "debe" means must.

My question is that does "debe" always mean "should", I thought it only meant "must" and that "debería" meant "should." Is what my teacher said correct or should she have used "debería"?

  • So if what my teacher said correct or incorrect? It is incorrect right?
    – Louis
    Feb 24, 2018 at 13:22

2 Answers 2


I think your confusion comes from two different forms of deber: deber and deber de, which are NOT the same. I see very surprising how nobody has highlighted this.

The conditional (debería) is used for advice and it is equivalent to "should".

For example: "I should go" is (yo) debería ir

This is easy to remember, so let's go to the key part.

"Deber" (non conditional) is used for compulsory duties, and it is equivalent to "must".

For example: "I must go" is (yo) debo ir.

However, there is a "phrase" that changes its meaning. When it is "deber de", it means "possibility" instead of duty.

"Deber de" indicates possibility/probability. It is different than just "deber".

It is probably the in the podium of the most commited mistakes in oral speech (sharing positions with "leísmo", "laísmo", or the imperative of "vosotros", haha).

When you say "deber de", it denotes possibility.

Example: Debe de haber 10 personas means "It must be 10 people", in the sense that "It is probable that there are about 10 people.

Check the difference:

"Debe ser grande" = It MUST be big


"Debe de ser grande" = It is probably big.

It can be sometimes hard to decide, but most examples are clear enough.

So, since this is a very common mistake, I just wanted to highlight it and point it out. If this wasn't yoru confusion, tell us.

  • Great answer, thank you very much. But my confusion is with the following phrase: 1) Si la palabra termina por "n", "s" o vocal, la sílaba tónica debe ser la sílaba "2." Si no cumple la norma, la palabra lleva acento en la sílaba tónica. In this phrase shouldn't my teacher have used "debería"?
    – Louis
    Feb 27, 2018 at 6:46
  • Whoa, that sentence is tricky. I had to read it twice. I'm so sorry but I still don't get where the confusion is. could you highlight the exact words that are causing problems? I don't see why you think there should be a "debería". This is a rule, so it's written as a mandate, using "must".
    – FGSUZ
    Feb 27, 2018 at 17:33
  • This is not really a rule, not all words follow this rule but most words should follow this rule. The teacher is meaning to express "should" but I'm wondering if "debería" is a more correct substitute of "debe".
    – Louis
    Mar 7, 2018 at 4:48
  • In spanishdict, it is written that deber ser means must be.
    – Louis
    Mar 7, 2018 at 4:50
  • In the original sentence you deleted, If I remember well, the usage of "debe" was right because it is a rule. A rule is not neccesarily a god's law: rules can be broken, and there are exceptions, but that doesn't invalidate a rule (as long as it keeps being true "in general")
    – FGSUZ
    Mar 7, 2018 at 14:07

My teacher says that "debe" means must.

My question is, does "debe" also mean "should"? I thought it only meant "must" and that "debería" meant "should." Is what my teacher said correct or should she have used "debería"?

Indeed, "debe" also means "should." You can see in WordReference.com that deber means:

have to, must, oblige [somebody] to, should

What your teacher wrote was fine. Her explanation of the verb "deber" was perhaps an oversimplification. I will encourage you to find a dictionary you like and make it your friend.

Note, there is often not a perfect one-to-one match between words of different languages. "Should" can be translated as both "debe" and "debería", depending on the context.

Here is a simplified way of thinking about the choice of debe/debería: debería often has more of an "ought to" feel than debe.

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