Deber – must, to have to

Deber - Spanish verb
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A Spanish verb must

Deber is a very common Spanish verb with regular conjugations and an unusual relationship to some of its English equivalents.* Deber has several meanings related to obligation, supposition, and expectation.

Deber = must, to have to (obligation)

Debes terminar este proyecto.   You must finish this project.
Debo salir a las 2 de la tarde.   I have to leave at 2pm.

Deber = must, to be probable (supposition)

Santiago debe estar trabajando hasta tarde.   Sylvain must be working late.
Debes estar cansado.   You’re probably tired.

Deber = to be expected, supposed to (expectation)

Debo llegar alrededor del mediodía.   I expect to, I should arrive around noon.
Anne debe llamar mañana.   Anne is supposed to call tomorrow.

Deber = to be bound to (fatalism)

Debes descubrir la verdad.   You’re bound to discover the truth.
Debe arruinarlo un día.   He was bound to screw it up one day.

 Should vs Must

Many of the above examples could fit into more than one category, so how do you know which meaning is the right one? As always, it depends on context. When you want to make sure that the meaning you want is the one others get, you need to do a bit more work.


To specify that something "must" happen, strengthen deber with something like absolutamente, a toda costa, imperativamente, or realmente.

Realmente debes terminar este proyecto.   You really must finish this project.
Tengo que salir a las 2 de la tarde a toda costa.   I have to leave at 2pm no matter what.


To say that something "should" happen, soften deber by using it in the conditional.

Deberías terminar este proyecto.   You should finish this project.
Debería salir a las 2 de la tarde.   I should leave at 2pm.

 * Whereas devoir is a fully conjugable verb, two of its common English equivalents – "must" and "should" – are modal verbs, which have just a single form.

Deber = to owe

Deber plus a noun means "to owe."

Le debo 5 euros.   I owe him 5 euros.
¡Me debes una explicación!   You owe me an explanation!

Deber conjugations

Present tense

Deber is a regular –er verb:

yo debo    nosotros  debemos
debes vosotros debéis
él, ella, Ud. debe ellos, ellas, Uds. deben

All tenses

Spanish quizzes Deber Conjugations Quiz

Think you’ve got it? Test yourself:

El deber = duty, los deberes = duties, homework

Hizo su deber.   He did his duty.
Hizo sus deberes.   He did his homework.

 Related lessons

Learn French En français

Learn Italian In italiano

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Deber - must, to have to

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