Alterar Conjugation in Spanish

The Spanish verb alterar means to alter, to disturb, and it is a verb you will use again and again once you know it. Alterar means to alter or to disturb, to change something from its normal state, such as plans, order or someone's calm. It is a fully regular verb used in everyday life, work and medicine. Like every Spanish verb, alterar 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 altero los planes del viaje, and in the preterite you say alteré la calma del barrio. 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: alterar
  • English: to alter, to disturb
  • Verb type: regular -ar verb
  • Ending: -ar
  • Gerund: alterando
  • Past participle: alterado
  • Auxiliary verb: haber (all perfect tenses are formed with haber + alterado)

Pronunciation is not listed on this page: the verified tables do not include IPA for alterar, so no pronunciation is given rather than an invented one. Alterar is fully regular: altero, altera. It changes something from its normal state, often for the worse; cambiar is the neutral word for change.

Full conjugation tables

Every form below comes from the verified conjugation tables for alterar. 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 altero
tú alteras
él/ella/Ud. altera
nosotros/as alteramos
vosotros/as alteráis
ellos/ellas/Uds. alteran

Preterite

Person Form
yo alteré
tú alteraste
él/ella/Ud. alteró
nosotros/as alteramos
vosotros/as alterasteis
ellos/ellas/Uds. alteraron

Imperfect

Person Form
yo alteraba
tú alterabas
él/ella/Ud. alteraba
nosotros/as alterábamos
vosotros/as alterabais
ellos/ellas/Uds. alteraban

Future

Person Form
yo alteraré
tú alterarás
él/ella/Ud. alterará
nosotros/as alteraremos
vosotros/as alteraréis
ellos/ellas/Uds. alterarán

Conditional

Person Form
yo alteraría
tú alterarías
él/ella/Ud. alteraría
nosotros/as alteraríamos
vosotros/as alteraríais
ellos/ellas/Uds. alterarían

Present perfect

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

Pluperfect

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

Future perfect

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

Conditional perfect

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

Present subjunctive

Person Form
yo altere
tú alteres
él/ella/Ud. altere
nosotros/as alteremos
vosotros/as alteréis
ellos/ellas/Uds. alteren

Imperfect subjunctive (-ra)

Person Form
yo alterara
tú alteraras
él/ella/Ud. alterara
nosotros/as alteráramos
vosotros/as alterarais
ellos/ellas/Uds. alteraran

Imperative (affirmative)

Person Form
tú altera
él/ella/Ud. altere
nosotros/as alteremos
vosotros/as alterad
ellos/ellas/Uds. alteren

Imperative (negative)

Person Form
tú alteres
él/ella/Ud. altere
nosotros/as alteremos
vosotros/as alteréis
ellos/ellas/Uds. alteren

Gerund and past participle

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

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 alterar, the present looks like this in a real sentence: Altero los planes del viaje. 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 alterar, the preterite looks like this in a real sentence: Ayer, alteré el orden de la casa. 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 alterar, the imperfect looks like this in a real sentence: De niño, alteraba la calma del barrio. 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 alterar, the future looks like this in a real sentence: Mañana, alteraré el resultado del análisis. 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 alterar, the conditional looks like this in a real sentence: Alteraría los planes del viaje 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 alterar, the present perfect looks like this in a real sentence: Hoy, he alterado el orden de la casa. 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 alterar, the pluperfect looks like this in a real sentence: Había alterado la calma del barrio 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 alterar, the future perfect looks like this in a real sentence: Para mañana, habré alterado el resultado del análisis. 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 alterar, the conditional perfect looks like this in a real sentence: Habría alterado los planes del viaje 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 alterar, the present subjunctive looks like this in a real sentence: Espero que él altere el orden de la casa. 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 alterar, the imperfect subjunctive looks like this in a real sentence: Si él alterara la calma del barrio, 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 alterar, the affirmative imperative looks like this in a real sentence: ¡Altera el resultado del análisis! 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 alterar, the negative imperative looks like this in a real sentence: No alteres los planes del viaje. 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 alterar, covering different tenses and persons. Each one uses a form from the tables above.

  1. Altero los planes del viaje. — I alter the travel plans.
  2. Altera el orden de la casa. — He/she alters the order of the house.
  3. Ayer, alteré la calma del barrio. — Yesterday, I altered the calm of the neighbourhood.
  4. Antes, nosotros alterábamos el resultado del análisis. — Before, we used to alter the result of the test.
  5. Mañana, tú alterarás los planes del viaje. — Tomorrow, you will alter the travel plans.
  6. Yo alteraría el orden de la casa si tuviera más tiempo. — I would alter the order of the house if I had more time.
  7. Él ha alterado la calma del barrio. — He has altered the calm of the neighbourhood.
  8. Espero que él altere el resultado del análisis. — I hope he alters the result of the test.
  9. Yo ya había alterado los planes del viaje antes de salir. — I had already altered the travel plans before leaving.
  10. Ellos alteraban el orden de la casa cuando eran jóvenes. — They used to alter the order of the house when they were young.

Common mistakes

  1. Wrong: Yo altera los planes del viaje. — Right: Yo altero los planes del viaje. — The person matters: altera is the él/ella/Ud. form, while the yo form is altero. Using the third-person form with yo is one of the most common beginner errors.
  2. Wrong: Ayer yo altero el orden de la casa. — Right: Ayer yo alteré el orden de la casa. — The present and the preterite are different tenses: altero is happening now, while alteré is a finished action in the past. Use the preterite with ayer.
  3. Wrong: Treating alterar and cambiar as identical in every context. — Right: Alterar means to alter, to disturb, while cambiar means to change. — They overlap, but each has uses the other does not: alterar fits sentences such as Altero los planes del viaje, while cambiar belongs in a different sentence. Check the meaning you want before choosing.
  4. Wrong: Yo soy alterado el orden de la casa. — Right: Yo he alterado el orden de la casa. — Spanish perfect tenses use haber, not ser: he alterado, has alterado, ha alterado. Ser plus the participle makes a passive, not a perfect tense.
  5. Wrong: De niño, yo alteré la calma del barrio todos los días. — Right: De niño, yo alteraba la calma del barrio todos los días. — For a repeated habit in the past, use the imperfect (alteraba), not the preterite. The preterite (alteré) is for one finished action.

Quiz: test yourself

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

  1. Complete the sentence: Yo ___ los planes del viaje. (present tense) A. altero B. alteras C. altera D. alteramos

  2. Complete the sentence: Ayer, él ___ el orden de la casa. (preterite) A. alteré B. alteraste C. alteraron D. alteró

  3. Complete the sentence: Antes, nosotros ___ la calma del barrio. (imperfect) A. alterabas B. alteraban C. alterábamos D. alteraba

  4. Complete the sentence: Mañana, tú ___ el resultado del análisis. (future) A. alteraremos B. alterarás C. alteraré D. alterará

  5. Complete the sentence: Yo ___ los planes del viaje si pudiera. (conditional) A. alteraría B. alterarías C. alterarían D. altero

  6. Complete the sentence: Espero que él ___ el orden de la casa. (present subjunctive) A. alteres B. alteremos C. altero D. altere

  7. Complete the sentence: Si yo ___ la calma del barrio, todo cambiaría. (imperfect subjunctive, -ra form) A. alteráramos B. altero C. alterara D. alteraras

  8. Complete the sentence: Nosotros ___ el resultado del análisis. (present perfect) A. han alterado B. hemos alterado C. he alterado D. has alterado

  9. Complete the command: ¡___ los planes del viaje! (affirmative imperative, tú) A. altera B. altere C. alteremos D. alterad

  10. Which is the gerund of alterar, used with estar for the progressive? A. alterado B. altero C. alteré D. alterando

Answer key

  1. altero — The first-person present of alterar is altero. The other options are the tú, él/ella and nosotros forms.
  2. alteró — The third-person preterite of alterar is alteró, the form for a single finished action in the past.
  3. alterábamos — The nosotros imperfect of alterar is alterábamos, used here for a repeated past habit.
  4. alterarás — The second-person future of alterar is alterarás.
  5. alteraría — The first-person conditional of alterar is alteraría, the form for what would happen.
  6. altere — After espero que, the subjunctive is required: the third-person present subjunctive of alterar is altere.
  7. alterara — The first-person imperfect subjunctive (-ra) of alterar is alterara.
  8. hemos alterado — The nosotros present perfect of alterar is hemos alterado: hemos + alterado.
  9. altera — The affirmative tú imperative of alterar is altera.
  10. alterando — The gerund of alterar is alterando: estoy alterando. The participle alterado is used with haber instead.

Frequently asked questions

What does alterar mean in English?

Alterar means to alter, to disturb. It is used in everyday situations such as Altero los planes del viaje. The exact English wording depends on the context, but the core meaning stays the same across the tenses.

Is alterar regular or irregular?

Alterar is a fully regular -ar 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 altero in the present and alteré in the preterite.

What is the difference between alterar and cambiar?

Alterar means to alter, to disturb, while cambiar means to change. They are easy to confuse because they appear in similar situations, but they are not interchangeable: use alterar when you mean to alter, to disturb, as in Altero los planes del viaje, and use cambiar for to change. When in doubt, check the object of the sentence — it usually shows which verb fits.

How do I say “I alter” in the past?

It depends on the kind of past. For one finished action, use the preterite: yo alteré el orden de la casa. For a repeated habit or background in the past, use the imperfect: yo alteraba la calma del barrio. For something that has just happened, use the present perfect: yo he alterado el orden de la casa.

How do I practise alterar?

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

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