Fortalecer Conjugation in Spanish
The Spanish verb fortalecer means to strengthen, and it is a verb you will use again and again once you know it. Fortalecer means to strengthen, and it covers strengthening muscles with exercise, strengthening a friendship and strengthening a team or an economy. It is the opposite of debilitar, and it is a -cer spelling-change verb. Like every Spanish verb, fortalecer 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 fortalezco los músculos con ejercicio, and in the preterite you say fortalecí el equipo con dos fichajes. 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: fortalecer
- English: to strengthen
- Verb type: irregular verb
- Ending: -er
- Gerund: fortaleciendo
- Past participle: fortalecido
- Auxiliary verb: haber (all perfect tenses are formed with haber + fortalecido)
Pronunciation is not listed on this page: the verified tables do not include IPA for fortalecer, so no pronunciation is given rather than an invented one. Spelling change: c becomes zc before o and a, so yo fortalezco and the subjunctive fortalezca.
Full conjugation tables
Every form below comes from the verified conjugation tables for fortalecer. 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 | fortalezco |
| tú | fortaleces |
| él/ella/Ud. | fortalece |
| nosotros/as | fortalecemos |
| vosotros/as | fortalecéis |
| ellos/ellas/Uds. | fortalecen |
Preterite
| Person | Form |
|---|---|
| yo | fortalecí |
| tú | fortaleciste |
| él/ella/Ud. | fortaleció |
| nosotros/as | fortalecimos |
| vosotros/as | fortalecisteis |
| ellos/ellas/Uds. | fortalecieron |
Imperfect
| Person | Form |
|---|---|
| yo | fortalecía |
| tú | fortalecías |
| él/ella/Ud. | fortalecía |
| nosotros/as | fortalecíamos |
| vosotros/as | fortalecíais |
| ellos/ellas/Uds. | fortalecían |
Future
| Person | Form |
|---|---|
| yo | fortaleceré |
| tú | fortalecerás |
| él/ella/Ud. | fortalecerá |
| nosotros/as | fortaleceremos |
| vosotros/as | fortaleceréis |
| ellos/ellas/Uds. | fortalecerán |
Conditional
| Person | Form |
|---|---|
| yo | fortalecería |
| tú | fortalecerías |
| él/ella/Ud. | fortalecería |
| nosotros/as | fortaleceríamos |
| vosotros/as | fortaleceríais |
| ellos/ellas/Uds. | fortalecerían |
Present perfect
| Person | Form |
|---|---|
| yo | he fortalecido |
| tú | has fortalecido |
| él/ella/Ud. | ha fortalecido |
| nosotros/as | hemos fortalecido |
| vosotros/as | habéis fortalecido |
| ellos/ellas/Uds. | han fortalecido |
Pluperfect
| Person | Form |
|---|---|
| yo | había fortalecido |
| tú | habías fortalecido |
| él/ella/Ud. | había fortalecido |
| nosotros/as | habíamos fortalecido |
| vosotros/as | habíais fortalecido |
| ellos/ellas/Uds. | habían fortalecido |
Future perfect
| Person | Form |
|---|---|
| yo | habré fortalecido |
| tú | habrás fortalecido |
| él/ella/Ud. | habrá fortalecido |
| nosotros/as | habremos fortalecido |
| vosotros/as | habréis fortalecido |
| ellos/ellas/Uds. | habrán fortalecido |
Conditional perfect
| Person | Form |
|---|---|
| yo | habría fortalecido |
| tú | habrías fortalecido |
| él/ella/Ud. | habría fortalecido |
| nosotros/as | habríamos fortalecido |
| vosotros/as | habríais fortalecido |
| ellos/ellas/Uds. | habrían fortalecido |
Present subjunctive
| Person | Form |
|---|---|
| yo | fortalezca |
| tú | fortalezcas |
| él/ella/Ud. | fortalezca |
| nosotros/as | fortalezcamos |
| vosotros/as | fortalecáis |
| ellos/ellas/Uds. | fortalezcan |
Imperfect subjunctive (-ra)
| Person | Form |
|---|---|
| yo | fortaleciera |
| tú | fortalecieras |
| él/ella/Ud. | fortaleciera |
| nosotros/as | fortaleciéramos |
| vosotros/as | fortalecierais |
| ellos/ellas/Uds. | fortalecieran |
Imperative (affirmative)
| Person | Form |
|---|---|
| tú | fortalece |
| él/ella/Ud. | fortalezca |
| nosotros/as | fortalezcamos |
| vosotros/as | fortaleced |
| ellos/ellas/Uds. | fortalezcan |
Imperative (negative)
| Person | Form |
|---|---|
| tú | fortalezcas |
| él/ella/Ud. | fortalezca |
| nosotros/as | fortalezcamos |
| vosotros/as | fortalecáis |
| ellos/ellas/Uds. | fortalezcan |
Gerund and past participle
| Form | Spanish | Use |
|---|---|---|
| Gerund | fortaleciendo | with estar for the progressive: estoy fortaleciendo |
| Past participle | fortalecido | with haber for the perfect tenses: he fortalecido |
How to use each tense
Present indicative
Use the present for routines, general facts and what is happening right now. Note the spelling change here: c becomes zc before o and a, so the forms keep the same sound as the infinitive. For fortalecer, the present looks like this in a real sentence: Fortalezco los músculos con ejercicio. 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 fortalecer, the preterite looks like this in a real sentence: Ayer, fortalecí la amistad con los años. 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 fortalecer, the imperfect looks like this in a real sentence: De niño, fortalecía el equipo con dos fichajes. 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 fortalecer, the future looks like this in a real sentence: Mañana, fortaleceré la economía del país. 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 fortalecer, the conditional looks like this in a real sentence: Fortalecería los músculos con ejercicio 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 fortalecer, the present perfect looks like this in a real sentence: Hoy, he fortalecido la amistad con los años. 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 fortalecer, the pluperfect looks like this in a real sentence: Había fortalecido el equipo con dos fichajes 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 fortalecer, the future perfect looks like this in a real sentence: Para mañana, habré fortalecido la economía del país. 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 fortalecer, the conditional perfect looks like this in a real sentence: Habría fortalecido los músculos con ejercicio 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. Note the spelling change here: c becomes zc before o and a, so the forms keep the same sound as the infinitive. For fortalecer, the present subjunctive looks like this in a real sentence: Espero que él fortalezca la amistad con los años. 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 fortalecer, the imperfect subjunctive looks like this in a real sentence: Si él fortaleciera el equipo con dos fichajes, 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. Note the spelling change here: c becomes zc before o and a, so the forms keep the same sound as the infinitive. For fortalecer, the affirmative imperative looks like this in a real sentence: ¡Fortalece la economía del país! 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. Note the spelling change here: c becomes zc before o and a, so the forms keep the same sound as the infinitive. For fortalecer, the negative imperative looks like this in a real sentence: No fortalezcas los músculos con ejercicio. 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 fortalecer, covering different tenses and persons. Each one uses a form from the tables above.
- Fortalezco los músculos con ejercicio. — I strengthen the muscles with exercise.
- Fortalece la amistad con los años. — He/she strengthens the friendship over the years.
- Ayer, fortalecí el equipo con dos fichajes. — Yesterday, I strengthened the team with two signings.
- Antes, nosotros fortalecíamos la economía del país. — Before, we used to strengthen the country's economy.
- Mañana, tú fortalecerás los músculos con ejercicio. — Tomorrow, you will strengthen the muscles with exercise.
- Yo fortalecería la amistad con los años si tuviera más tiempo. — I would strengthen the friendship over the years if I had more time.
- Él ha fortalecido el equipo con dos fichajes. — He has strengthened the team with two signings.
- Espero que él fortalezca la economía del país. — I hope he strengthens the country's economy.
- Yo ya había fortalecido los músculos con ejercicio antes de salir. — I had already strengthened the muscles with exercise before leaving.
- Ellos fortalecían la amistad con los años cuando eran jóvenes. — They used to strengthen the friendship over the years when they were young.
Common mistakes
- Wrong: Yo fortalece los músculos con ejercicio. — Right: Yo fortalezco los músculos con ejercicio. — The person matters: fortalece is the él/ella/Ud. form, while the yo form is fortalezco. Using the third-person form with yo is one of the most common beginner errors.
- Wrong: Yo fortaleco la amistad con los años. — Right: Yo fortalezco la amistad con los años. — In the present, the correct first-person form is fortalezco, not fortaleco. fortalecer is a spelling-change verb: c becomes zc before o and a, so the written form changes to keep the same sound. The regular-looking form is wrong.
- Wrong: Treating fortalecer and debilitar as identical in every context. — Right: Fortalecer means to strengthen, while debilitar means to weaken, its opposite. — They overlap, but each has uses the other does not: fortalecer fits sentences such as Fortalezco los músculos con ejercicio, while debilitar belongs in a different sentence. Check the meaning you want before choosing.
- Wrong: Yo soy fortalecido la amistad con los años. — Right: Yo he fortalecido la amistad con los años. — Spanish perfect tenses use haber, not ser: he fortalecido, has fortalecido, ha fortalecido. Ser plus the participle makes a passive, not a perfect tense.
- Wrong: De niño, yo fortalecí el equipo con dos fichajes todos los días. — Right: De niño, yo fortalecía el equipo con dos fichajes todos los días. — For a repeated habit in the past, use the imperfect (fortalecía), not the preterite. The preterite (fortalecí) is for one finished action.
Quiz: test yourself
Ten questions on fortalecer. Choose the right form, then check the answer key below.
Complete the sentence: Yo ___ los músculos con ejercicio. (present tense) A. fortalezco B. fortaleces C. fortalece D. fortalecemos
Complete the sentence: Ayer, él ___ la amistad con los años. (preterite) A. fortalecí B. fortaleciste C. fortalecieron D. fortaleció
Complete the sentence: Antes, nosotros ___ el equipo con dos fichajes. (imperfect) A. fortalecías B. fortalecían C. fortalecíamos D. fortalecía
Complete the sentence: Mañana, tú ___ la economía del país. (future) A. fortaleceremos B. fortalecerás C. fortaleceré D. fortalecerá
Complete the sentence: Yo ___ los músculos con ejercicio si pudiera. (conditional) A. fortalecería B. fortalecerías C. fortalecerían D. fortalezco
Complete the sentence: Espero que él ___ la amistad con los años. (present subjunctive) A. fortalezcas B. fortalezcamos C. fortalezco D. fortalezca
Complete the sentence: Si yo ___ el equipo con dos fichajes, todo cambiaría. (imperfect subjunctive, -ra form) A. fortaleciéramos B. fortalezco C. fortaleciera D. fortalecieras
Complete the sentence: Nosotros ___ la economía del país. (present perfect) A. han fortalecido B. hemos fortalecido C. he fortalecido D. has fortalecido
Complete the command: ¡___ los músculos con ejercicio! (affirmative imperative, tú) A. fortalece B. fortalezca C. fortalezcamos D. fortaleced
Which is the gerund of fortalecer, used with estar for the progressive? A. fortalecido B. fortalezco C. fortalecí D. fortaleciendo
Answer key
- fortalezco — The first-person present of fortalecer is fortalezco. The other options are the tú, él/ella and nosotros forms.
- fortaleció — The third-person preterite of fortalecer is fortaleció, the form for a single finished action in the past.
- fortalecíamos — The nosotros imperfect of fortalecer is fortalecíamos, used here for a repeated past habit.
- fortalecerás — The second-person future of fortalecer is fortalecerás.
- fortalecería — The first-person conditional of fortalecer is fortalecería, the form for what would happen.
- fortalezca — After espero que, the subjunctive is required: the third-person present subjunctive of fortalecer is fortalezca.
- fortaleciera — The first-person imperfect subjunctive (-ra) of fortalecer is fortaleciera.
- hemos fortalecido — The nosotros present perfect of fortalecer is hemos fortalecido: hemos + fortalecido.
- fortalece — The affirmative tú imperative of fortalecer is fortalece.
- fortaleciendo — The gerund of fortalecer is fortaleciendo: estoy fortaleciendo. The participle fortalecido is used with haber instead.
Frequently asked questions
What does fortalecer mean in English?
Fortalecer means to strengthen. It is used in everyday situations such as Fortalezco los músculos con ejercicio. The exact English wording depends on the context, but the core meaning stays the same across the tenses.
Is fortalecer regular or irregular?
Fortalecer is a fully regular -er 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 fortalezco in the present and fortalecí in the preterite.
What is the difference between fortalecer and debilitar?
Fortalecer means to strengthen, while debilitar means to weaken, its opposite. They are easy to confuse because they appear in similar situations, but they are not interchangeable: use fortalecer when you mean to strengthen, as in Fortalezco los músculos con ejercicio, and use debilitar for to weaken, its opposite. When in doubt, check the object of the sentence — it usually shows which verb fits.
How do I say “I strengthen” in the past?
It depends on the kind of past. For one finished action, use the preterite: yo fortalecí la amistad con los años. For a repeated habit or background in the past, use the imperfect: yo fortalecía el equipo con dos fichajes. For something that has just happened, use the present perfect: yo he fortalecido la amistad con los años.
How do I practise fortalecer?
Start with the present tense table, then drill the preterite and the imperfect, since those two past tenses cause the most mistakes. Try the fortalecer examples and quiz page for more sentences, and use the Spanish Verb Quiz to test the forms under pressure.
Related links
- Fortalecer in the present tense — the full present-tense table for fortalecer.
- Fortalecer examples and quiz — more example sentences and practice for fortalecer.
- Spanish verbs — the Spanish hub, with every verb and tense guide.
- Empobrecer conjugation — another -er verb to compare with fortalecer.
- Enriquecer conjugation — another -er verb to compare with fortalecer.
- Oscurecer conjugation — another -er verb to compare with fortalecer.
- Spanish Verb Conjugator — conjugate any Spanish verb in every tense.
- Spanish Verb Quiz — test yourself on real conjugated forms.