Ser: Full Conjugation

Ser is one of the most irregular verbs in Spanish, and also one of the most frequent. Its forms come from several different Latin roots, which is why the stems change dramatically between tenses. In Latin America, ustedes is used for all second-person plural forms, so you will not see vosotros in these tables.

This page lists the full conjugation. For when to use ser versus estar, see Ser: Uses and Ser vs Estar: Overview.

Present indicative

The present tense forms are highly irregular. Note that eres is the only form starting with er-.

Tenseyotúél/ella/ustednosotrosellos/ellas/ustedes
Presentsoyeresessomosson

Yo soy profesora de matemáticas.

I am a math teacher.

Nosotros somos de Colombia, pero ellos son de México.

We are from Colombia, but they are from Mexico.

Preterite

The preterite of ser is identical to the preterite of ir (to go). Context always makes the meaning clear.

Tenseyotúél/ella/ustednosotrosellos/ellas/ustedes
Preteritefuifuistefuefuimosfueron

La reunión fue muy productiva ayer.

The meeting was very productive yesterday.

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The preterite forms fui, fue, fuiste do not carry accent marks in modern Spanish. Older texts sometimes write fué or fuí, but these accents were officially removed.

Imperfect

The imperfect of ser is one of only three verbs in Spanish with an irregular imperfect (the others are ir and ver).

Tenseyotúél/ella/ustednosotrosellos/ellas/ustedes
Imperfecteraeraseraéramoseran

Cuando era niño, mi casa era muy pequeña.

When I was a child, my house was very small.

Mis abuelos eran campesinos.

My grandparents were farmers.

Future and conditional

Both the future and the conditional use the full infinitive ser as the stem, so they are perfectly regular.

Tenseyotúél/ella/ustednosotrosellos/ellas/ustedes
Futureseréserásseráseremosserán
Conditionalseríaseríasseríaseríamosserían

Algún día seré médico.

Someday I will be a doctor.

Sería una buena idea llamar primero.

It would be a good idea to call first.

Present subjunctive

The present subjunctive stem is se-, making it fully predictable once you know the first form.

Tenseyotúél/ella/ustednosotrosellos/ellas/ustedes
Present subjunctiveseaseasseaseamossean

Quiero que seas feliz.

I want you to be happy.

Imperfect subjunctive

Built from the third-person plural preterite fueron, the imperfect subjunctive has two interchangeable sets of endings. The -ra forms are far more common in spoken Latin American Spanish.

Tenseyotúél/ella/ustednosotrosellos/ellas/ustedes
Imperfect subj. (-ra)fuerafuerasfuerafuéramosfueran
Imperfect subj. (-se)fuesefuesesfuesefuésemosfuesen

Si yo fuera tú, aceptaría el trabajo.

If I were you, I would accept the job.

Imperative

The informal tú command is the single syllable sé, with a written accent to distinguish it from the reflexive pronoun se. The usted and ustedes commands come directly from the subjunctive.

Tensetúustednosotrosustedes
Affirmativeséseaseamossean
Negativeno seasno seano seamosno sean

¡Sé amable con tu hermana!

Be kind to your sister!

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Remember: sé (with accent) = "be!" or "I know", while se (no accent) is a pronoun. The context and the accent keep them apart.

Related Topics

  • Ser: UsesA1 — When to use ser: identity, origin, time, possession, and inherent characteristics.
  • Ser vs Estar: OverviewA2 — A decision framework for choosing between ser and estar, with mnemonics and a decision tree.
  • Estar: Full ConjugationA1 — Complete conjugation of estar, with attention to the accented present and the irregular preterite.