deber + Infinitive

Duty/Should

Level 1

Use 'deber + infinitive' to say what someone 'should' or 'ought to' do.

How It Works

The structure deber + infinitive is used to express a sense of duty, moral obligation, or strong advice. It's the equivalent of 'should' or 'must' in English.

To use it, you simply conjugate deber according to the subject and then add the main action verb in its infinitive form. Deber is a regular -er verb.

Present Tense Conjugation of Deber:

  • (yo) debo
  • (tú) debes
  • (él/ella/usted) debe
  • (nosotros/as) debemos
  • (vosotros/as) debéis
  • (ellos/ellas/ustedes) deben

Compare tener que + infinitive, which often presents necessity imposed by circumstances. Deber can present a norm, duty or advice. Their force depends on tense and context; there is no fixed strength scale.

Deber And Deber De
For the basic obligation pattern, use Debo trabajar mañana. Deber without de can also express an inference: Debe estar en casa means the speaker thinks the person is at home. Deber de commonly expresses that inference, but the current DPD also records obligation uses in educated speech and writing. Treat the contrast as a useful preference, not a categorical ban on obligation with de. The force of advice or obligation also depends on tense and context: compare debes and deberías.

Examples (5)

  1. Debo estudiar para el examen.

    I must/should study for the exam.

    Word by Word: I must to study for the exam.

  2. No debes comer tantos dulces.

    You shouldn't eat so many sweets.

    Word by Word: Not you should to eat so many sweets.

  3. Ella debe llamar a sus abuelos.

    She should call her grandparents.

    Word by Word: She should to call to her grandparents.

  4. Debemos respetar a los demás.

    We must respect others.

    Word by Word: We must to respect to the others.

  5. ¿Qué debo hacer?

    What should I do?

    Word by Word: What I should to do?

Common Mistakes

  • Conjugating the second verb instead of using the infinitive.

    Yo debo estudio más.
    Yo debo estudiar más.

    In this deber + infinitive construction, use estudiar, not the independently conjugated estudio. Deber may also be a lexical verb meaning owe, as in Debo diez euros; that is a different use.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

deber + InfinitiveLevel 1Duty/Should

Learn This First

To use 'deber + infinitive', you need to know how to conjugate regular -er verbs in the present tense and understand the structure of combining a conjugated auxiliary verb with a base infinitive to express necessity or duty.

Words in This Pattern

deber