Unir Conjugation in Spanish

The Spanish verb unir means to join, to unite, and it is a verb you will use again and again once you know it. Unir means to join or to unite, and it covers joining two pieces, uniting people and joining a club: unir las piezas, unir a la familia. It is a regular -ir verb. Its reflexive partner unirse means to join a group yourself. Like every Spanish verb, unir changes its ending for each person and tense, and this page gives you the complete picture: every tense, every person, the gerund and the past participle, all from the verified conjugation tables. For example, in the present tense you say uno las piezas del puzzle, and in the preterite you say uní dos cables con cinta. Work through the tables below, read the notes for each tense, and then test yourself with the examples, the common mistakes and the quiz at the end of the page.

Quick facts

  • Infinitive: unir
  • English: to join, to unite
  • Verb type: regular -ir verb
  • Ending: -ir
  • Gerund: uniendo
  • Past participle: unido
  • Auxiliary verb: haber (all perfect tenses are formed with haber + unido)

Pronunciation is not listed on this page: the verified tables do not include IPA for unir, so no pronunciation is given rather than an invented one. Unir is regular: uní, unía, uniré. Unir a la familia is to bring the family together.

Full conjugation tables

Every form below comes from the verified conjugation tables for unir. The imperfect subjunctive is shown in its -ra forms; the -se forms use the same stem. For reflexive verbs, the pronoun column shows the reflexive pronoun that goes before each form.

Present indicative

Person Form
yo uno
tú unes
él/ella/Ud. une
nosotros/as unimos
vosotros/as unís
ellos/ellas/Uds. unen

Preterite

Person Form
yo uní
tú uniste
él/ella/Ud. unió
nosotros/as unimos
vosotros/as unisteis
ellos/ellas/Uds. unieron

Imperfect

Person Form
yo unía
tú unías
él/ella/Ud. unía
nosotros/as uníamos
vosotros/as uníais
ellos/ellas/Uds. unían

Future

Person Form
yo uniré
tú unirás
él/ella/Ud. unirá
nosotros/as uniremos
vosotros/as uniréis
ellos/ellas/Uds. unirán

Conditional

Person Form
yo uniría
tú unirías
él/ella/Ud. uniría
nosotros/as uniríamos
vosotros/as uniríais
ellos/ellas/Uds. unirían

Present perfect

Person Form
yo he unido
tú has unido
él/ella/Ud. ha unido
nosotros/as hemos unido
vosotros/as habéis unido
ellos/ellas/Uds. han unido

Pluperfect

Person Form
yo había unido
tú habías unido
él/ella/Ud. había unido
nosotros/as habíamos unido
vosotros/as habíais unido
ellos/ellas/Uds. habían unido

Future perfect

Person Form
yo habré unido
tú habrás unido
él/ella/Ud. habrá unido
nosotros/as habremos unido
vosotros/as habréis unido
ellos/ellas/Uds. habrán unido

Conditional perfect

Person Form
yo habría unido
tú habrías unido
él/ella/Ud. habría unido
nosotros/as habríamos unido
vosotros/as habríais unido
ellos/ellas/Uds. habrían unido

Present subjunctive

Person Form
yo una
tú unas
él/ella/Ud. una
nosotros/as unamos
vosotros/as unáis
ellos/ellas/Uds. unan

Imperfect subjunctive (-ra)

Person Form
yo uniera
tú unieras
él/ella/Ud. uniera
nosotros/as uniéramos
vosotros/as unierais
ellos/ellas/Uds. unieran

Imperative (affirmative)

Person Form
tú une
él/ella/Ud. una
nosotros/as unamos
vosotros/as unid
ellos/ellas/Uds. unan

Imperative (negative)

Person Form
tú unas
él/ella/Ud. una
nosotros/as unamos
vosotros/as unáis
ellos/ellas/Uds. unan

Gerund and past participle

Form Spanish Use
Gerund uniendo with estar for the progressive: estoy uniendo
Past participle unido with haber for the perfect tenses: he unido

How to use each tense

Present indicative

Use the present for routines, general facts and what is happening right now. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the present looks like this in a real sentence: Uno las piezas del puzzle. Learn the present forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Preterite

Use the preterite for finished actions with a clear end, often with ayer, el año pasado or anoche. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the preterite looks like this in a real sentence: Ayer, uní a la familia en Navidad. Learn the preterite forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Imperfect

Use the imperfect for background, habits and actions in progress in the past, often with de niño, antes or mientras. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the imperfect looks like this in a real sentence: De niño, unía dos cables con cinta. Learn the imperfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Future

Use the future for plans, predictions and promises, often with mañana, el año que viene or pronto. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the future looks like this in a real sentence: Mañana, uniré los puntos con una línea. Learn the future forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Conditional

Use the conditional for polite requests, hypotheticals and what would happen, often with si clauses. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the conditional looks like this in a real sentence: Uniría las piezas del puzzle si pudiera. Learn the conditional forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Present perfect

Use the present perfect for recent actions and experiences, often with hoy, esta semana or ya. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the present perfect looks like this in a real sentence: Hoy, he unido a la familia en Navidad. Learn the present perfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Pluperfect

Use the pluperfect when one past action happened before another past action. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the pluperfect looks like this in a real sentence: Había unido dos cables con cinta antes de salir. Learn the pluperfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Future perfect

Use the future perfect for something that will already be finished by a future time. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the future perfect looks like this in a real sentence: Para mañana, habré unido los puntos con una línea. Learn the future perfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Conditional perfect

Use the conditional perfect for what would have happened under different conditions. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the conditional perfect looks like this in a real sentence: Habría unido las piezas del puzzle con más tiempo. Learn the conditional perfect forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Present subjunctive

Use the present subjunctive after expressions of wish, doubt, emotion and hope, such as espero que or quiero que. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the present subjunctive looks like this in a real sentence: Espero que él una a la familia en Navidad. Learn the present subjunctive forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Imperfect subjunctive (-ra)

Use the imperfect subjunctive after past wishes and in si clauses about the past, and note the -ra forms shown here; the -se forms use the same stem. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the imperfect subjunctive looks like this in a real sentence: Si él uniera dos cables con cinta, todo cambiaría. Learn the imperfect subjunctive forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Imperative (affirmative)

Use the affirmative imperative for direct commands, instructions and invitations. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the affirmative imperative looks like this in a real sentence: ¡Une los puntos con una línea! Learn the affirmative imperative forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Imperative (negative)

Use the negative imperative, always with no, to tell someone not to do something. For this verb the tense is regular, so the forms follow the standard endings for its verb class. For unir, the negative imperative looks like this in a real sentence: No unas las piezas del puzzle. Learn the negative imperative forms in the table above alongside this example, and notice how the ending, not the stem, usually carries the meaning of the tense.

Example sentences

Ten natural sentences with unir, covering different tenses and persons. Each one uses a form from the tables above.

  1. Uno las piezas del puzzle. — I join the puzzle pieces.
  2. Une a la familia en Navidad. — He/she joins the family at Christmas.
  3. Ayer, uní dos cables con cinta. — Yesterday, I joined two cables with tape.
  4. Antes, nosotros uníamos los puntos con una línea. — Before, we used to join the dots with a line.
  5. Mañana, tú unirás las piezas del puzzle. — Tomorrow, you will join the puzzle pieces.
  6. Yo uniría a la familia en Navidad si tuviera más tiempo. — I would join the family at Christmas if I had more time.
  7. Él ha unido dos cables con cinta. — He has joined two cables with tape.
  8. Espero que él una los puntos con una línea. — I hope he joins the dots with a line.
  9. Yo ya había unido las piezas del puzzle antes de salir. — I had already joined the puzzle pieces before leaving.
  10. Ellos unían a la familia en Navidad cuando eran jóvenes. — They used to join the family at Christmas when they were young.

Common mistakes

  1. Wrong: Yo une las piezas del puzzle. — Right: Yo uno las piezas del puzzle. — The person matters: une is the él/ella/Ud. form, while the yo form is uno. Using the third-person form with yo is one of the most common beginner errors.
  2. Wrong: Ayer yo uno a la familia en Navidad. — Right: Ayer yo uní a la familia en Navidad. — The present and the preterite are different tenses: uno is happening now, while uní is a finished action in the past. Use the preterite with ayer.
  3. Wrong: Treating unir and unirse as identical in every context. — Right: Unir means to join, to unite, while unirse means to join a group yourself. — They overlap, but each has uses the other does not: unir fits sentences such as Uno las piezas del puzzle, while unirse belongs in a different sentence. Check the meaning you want before choosing.
  4. Wrong: Yo soy unido a la familia en Navidad. — Right: Yo he unido a la familia en Navidad. — Spanish perfect tenses use haber, not ser: he unido, has unido, ha unido. Ser plus the participle makes a passive, not a perfect tense.
  5. Wrong: De niño, yo uní dos cables con cinta todos los días. — Right: De niño, yo unía dos cables con cinta todos los días. — For a repeated habit in the past, use the imperfect (unía), not the preterite. The preterite (uní) is for one finished action.

Quiz: test yourself

Ten questions on unir. Choose the right form, then check the answer key below.

  1. Complete the sentence: Yo ___ las piezas del puzzle. (present tense) A. uno B. unes C. une D. unimos

  2. Complete the sentence: Ayer, él ___ a la familia en Navidad. (preterite) A. uní B. uniste C. unimos D. unió

  3. Complete the sentence: Antes, nosotros ___ dos cables con cinta. (imperfect) A. unías B. uno C. uníamos D. unía

  4. Complete the sentence: Mañana, tú ___ los puntos con una línea. (future) A. uniremos B. unirás C. uniré D. unirá

  5. Complete the sentence: Yo ___ las piezas del puzzle si pudiera. (conditional) A. uniría B. unirías C. uniríamos D. uno

  6. Complete the sentence: Espero que él ___ a la familia en Navidad. (present subjunctive) A. unas B. unamos C. uno D. una

  7. Complete the sentence: Si yo ___ dos cables con cinta, todo cambiaría. (imperfect subjunctive, -ra form) A. uniéramos B. uno C. uniera D. unieras

  8. Complete the sentence: Nosotros ___ los puntos con una línea. (present perfect) A. ha unido B. hemos unido C. he unido D. has unido

  9. Complete the command: ¡___ las piezas del puzzle! (affirmative imperative, tú) A. une B. una C. unamos D. unid

  10. Which is the gerund of unir, used with estar for the progressive? A. unido B. uno C. uní D. uniendo

Answer key

  1. uno — The yo present tense of unir is uno.
  2. unió — The él/ella/Ud. preterite of unir is unió.
  3. uníamos — The nosotros/as imperfect of unir is uníamos.
  4. unirás — The tú future of unir is unirás.
  5. uniría — The yo conditional of unir is uniría.
  6. una — The él/ella/Ud. present subjunctive of unir is una.
  7. uniera — The yo imperfect subjunctive, -ra form of unir is uniera.
  8. hemos unido — The nosotros/as present perfect of unir is hemos unido.
  9. une — The affirmative tú imperative of unir is une.
  10. uniendo — The gerund of unir is uniendo: estoy uniendo. The participle unido is used with haber instead.

Frequently asked questions

What does unir mean in English?

Unir means to join, to unite. It is used in everyday situations such as Uno las piezas del puzzle. The exact English wording depends on the context, but the core meaning stays the same across the tenses.

Is unir regular or irregular?

Unir is a fully regular -ir verb, so every tense follows the standard endings for its class. Once you know the regular pattern, you can produce every form on this page, including uno in the present and uní in the preterite.

What is the difference between unir and unirse?

Unir means to join, to unite, while unirse means to join a group yourself. They are easy to confuse because they appear in similar situations, but they are not interchangeable: use unir when you mean to join, to unite, as in Uno las piezas del puzzle, and use unirse for to join a group yourself. When in doubt, check the object of the sentence — it usually shows which verb fits.

How do I say “I join” in the past?

It depends on the kind of past. For one finished action, use the preterite: yo uní a la familia en Navidad. For a repeated habit or background in the past, use the imperfect: yo unía dos cables con cinta. For something that has just happened, use the present perfect: yo he unido a la familia en Navidad.

How do I practise unir?

Start with the present tense table, then drill the preterite and the imperfect, since those two past tenses cause the most mistakes. Try the unir examples and quiz page for more sentences, and use the Spanish Verb Quiz to test the forms under pressure.

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