# ser conjugation

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Updated 2026-10-23 · HTML version: https://learnwithkin.com/spanish/conjugations/ser

> *Ser* is irregular and it is the verb you will use most. In the present it conjugates like an *-ar* verb (*soy, eres, es*), not like the *-er* verb it looks like. In the past it is like *-er* (*fui, fuiste, fue*). Use *ser* for identity, origin, characteristics and permanent states — *soy de México*, *es inteligente* — and *estar* for states and locations.

**Diagram.** ser is an -er verb that takes -ar endings in the present. Learn the present as its own set; the rest follows the -er family.
> A diagram showing that the Spanish verb ser, although it ends in -er, takes the -ar endings in the present tense: soy, eres, es, somos, sois, son.
- Forms to learn on their own: present, soy, eres, es, somos, sois, son, fui, fuiste, fue, fueron.
- Forms that follow a pattern: ser, imperfect, preterite, era, eras, eran.
- **Red pencil** marks the forms you have to learn on their own. Everything in graphite follows a pattern.
- The preterite of *ser* is the same as the preterite of *ir*: *fue* means both "he was" and "he went".

**ser** — to be. *Soy*. One of the two verbs Spanish uses for "to be", and the one that changes most often.

## Present indicative


| Pronoun | ser | Say |
| --- | --- | --- |
| yo | soy | soi |
| tú | eres | EH-rehs |
| él / ella / usted | es | ehs |
| nosotros | somos | SOH-mohs |
| vosotros | sois | SO-is |
| ellos / ellas / ustedes | son | sohn |

This is the irregular part. *Ser* is an *-er* verb by its infinitive, so you'd expect *sero, seres*, but the present takes the *-ar* endings instead: *soy, eres, es*. Learn this set on its own.

## Preterite


| Pronoun | ser | Say |
| --- | --- | --- |
| yo | fui | foo-EE |
| tú | fuiste | WEES-teh |
| él / ella / usted | fue | weh |
| nosotros | fuimos | FOO-mohs |
| vosotros | fuisteis | WEES-te-ees |
| ellos / ellas / ustedes | fueron | weh-ROHN |

Also irregular: the past of *ser* and *ir* are identical in every form except *vosotros*, where *ser* is *fuisteis* and *ir* is *fuisteis* too in speech — *fuisteis* — though the forms are written differently (*fuisteis* / *fuisteis*). In practice the preterite of *ser* is the same as the preterite of *ir*, and both mean "was" in the sense of *ser* and "went" in the sense of *ir*.

## Imperfect


| Pronoun | ser | Say |
| --- | --- | --- |
| yo | era | EH-rah |
| tú | eras | EH-rahs |
| él / ella / usted | era | EH-rah |
| nosotros | éramos | EH-rah-mohs |
| vosotros | erais | EH-rah-ees |
| ellos / ellas / ustedes | eran | EH-rahn |

## Future and conditional


| Pronoun | Future | Conditional |
| --- | --- | --- |
| yo | seré | sería |
| tú | serás | serías |
| él / ella / usted | será | sería |
| nosotros | seremos | seríamos |
| vosotros | seréis | seríais |
| ellos / ellas / ustedes | serán | serían |

Both are regular: drop *-er* and add the future or conditional endings. The future of *ser* is also the word for *saturday* in some contexts, and *será* is used as a polite future — *será un placer* (it will be a pleasure).

## Subjunctive


| Pronoun | Present subj. | Imperfect subj. |
| --- | --- | --- |
| yo | sea | fuera |
| tú | seas | fueras |
| él / ella / usted | sea | fuera |
| nosotros | seamos | fuéramos |
| vosotros | seáis | fuerais |
| ellos / ellas / ustedes | sean | fueran |

## Imperative


| Pronoun | Affirmative | Negative |
| --- | --- | --- |
| tú | sé | no sé |
| usted | sea | no sea |
| nosotros | seamos | no seamos |
| vosotros | sed | no seáis |
| ustedes | sean | no sean |

## ser or estar?

*The distinction people get wrong most*

| Use ser for | Use estar for |
| --- | --- |
| identity — *Ella es médica* (she is a doctor) | state — *está cansada* (she is tired) |
| origin — *es de Oaxaca* (she is from Oaxaca) | location — *está en Oaxaca* (she is in Oaxaca) |
| characteristics — *es simpático* (he is friendly) | mood — *está alegre* (he's happy) |
| material — *es de madera* (it's wood) | result of a change — *la puerta está abierta* (the door is open) |
| time and dates — *es martes* (it's Tuesday) | weather — *está lloviendo* (it's raining) |
| price — *es caro* (it's expensive) | in-progress — *estamos trabajando* (we're working) |

A useful test: *estar* is for things that could change, *ser* is for things that are defining. *Es aburrido* (he's boring — a character trait) but *está aburrido* (he's bored — right now). *El café está frío* (the coffee has gone cold) but *es frío* (it's a cold drink, as a quality). And where the two verbs overlap, *ser* is the default: if you're unsure, use *ser*.

**Soy** is also one of the most useful phrases in Spanish for saying who you are and where you're from, and it changes form for a reason: *SoyMexicana* becomes *soy mexicana* for a woman, and *soy mexicano* for a man. The adjective agrees with the person, not the speaker.

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## Questions

### Is ser the same as estar?

No, and this is the single most important verb distinction in Spanish. *Ser* is for identity, origin, characteristics and permanent states; *estar* is for states, locations, and anything temporary. *Soy feliz* (I am happy, as a person) but *estoy feliz* (I am happy, right now).

### What is the difference between fui and era?

*Fui* is the preterite: one completed event. *Era* is the imperfect: ongoing or habitual. *Fui a México* (I went to Mexico — once, done). *Era de México* (I was from Mexico — a state of affairs that lasted). With *ser*, *fue* also means "he/she was" as in "he was famous."

### Why does ser take -ar endings in the present?

Historical accident. *Ser* comes from a Latin verb whose present stem ended in *-s-*, and it kept that stem when the endings changed. That's why *soy, eres, es* don't match the *-er* family (*como, comes, come*), even though the infinitive ends in *-er*.

### Do I need the subjunctive forms of ser?

You'll need them less often than you'd think, but they're worth recognising. *Quiero que seas feliz* (I want you to be happy) uses the present subjunctive; *Sería bueno* (it would be good) uses the imperfect subjunctive via the conditional. Recognising the *sea* and *fuera* forms is enough for most reading.

## Related

- [estar conjugation](https://learnwithkin.com/spanish/conjugations/estar.md)
- [Spanish verb conjugations](https://learnwithkin.com/spanish/conjugations.md)
- [How long does it really take to learn Spanish?](https://learnwithkin.com/spanish/how-long-to-learn.md)

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