Spanish Infinitives — What They Are and How to Use Them

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In English the infinitive — “to speak,” “to eat,” “to live” — is mostly a grammar term. You see it in textbooks and that’s about it. In real conversation you rarely use it directly.

Spanish works differently. The infinitive does two jobs that English speakers often miss — and missing them creates confusion that follows learners for years.

The first job: the infinitive is the base form every conjugation is built from. You can’t conjugate a verb you don’t understand as an infinitive first. The stem carries the meaning. The ending changes to show who is acting and when.

The second job: the infinitive is used whole — unchanged — after certain verbs and prepositions in real everyday sentences. Quiero hablar. Tengo que comer. Voy a vivir aquí. The first verb conjugates. The second stays in its infinitive form.

Once you understand both jobs, every verb you encounter starts to make sense — in the dictionary, in conjugation charts, and in real sentences.

What the Infinitive Is

Before a verb is conjugated, it’s in its base form — the infinitive:

• hablar (to speak)
• comer (to eat)
• vivir (to live)

This is the form you find in the dictionary. Every Spanish infinitive ends in one of three ways:

-ar — hablar (to speak)
-er — comer (to eat)
-ir — vivir (to live)

That ending tells you two things: that this is an infinitive, and which conjugation pattern the verb follows.

Each infinitive has two parts:

stem | ending
habl | ar
com | er
viv | ir

The stem carries the meaning. The ending changes to show who is doing the action and when — that’s conjugation. But before any of that happens, the infinitive is the whole verb in its unchanged form.

• The stem carries the meaning.
• The ending changes to match WHO/WHEN/MOOD.

Examples from real sentences — infinitive to conjugated form:

• ganar → ganan
  Ellos siempre ganan. — They always win.
• venir → viene
  Viene el doctor. — The doctor is coming.
• correr → corre
  El perro corre. — The dog runs.

In each case, the stem stays. The ending changes. That’s the system.

Job 1 — The Infinitive as the Base for Conjugation

Every conjugated Spanish verb starts as an infinitive. To conjugate a verb, you remove the infinitive ending and replace it with the ending that matches the subject and tense.

hablar → habl- + o = hablo (I speak)
hablar → habl- + as = hablas (you speak)
hablar → habl- + a = habla (he/she speaks)

comer → com- + o = como (I eat)
comer → com- + es = comes (you eat)
comer → com- + e = come (he/she eats)

vivir → viv- + o = vivo (I live)
vivir → viv- + es = vives (you live)
vivir → viv- + e = vive (he/she lives)

This is why learning a verb means learning its infinitive first. The infinitive gives you the stem — and the stem is the foundation every tense is built on.

When you look up a verb in the dictionary, you always find the infinitive. When you see a new verb in a conjugation chart, the infinitive is listed at the top. When a native speaker teaches you a new verb, they give you the infinitive. It’s the entry point for everything.

Job 2 — The Infinitive Used Whole in Real Sentences

This is the job English speakers miss most — and it’s the one that shows up constantly in everyday Spanish.

After certain verbs and verb phrases, the second verb stays in its infinitive form. It doesn’t conjugate. The first verb carries all the person and tense information. The second verb stays unchanged.

The pattern:
Conjugated verb + infinitive

Common verbs that trigger this pattern:

querer — to want

• Quiero hablar. — I want to speak.
• Quieres comer. — You want to eat.
• Quiere vivir aquí. — He wants to live here.

poder — to be able to / can

• Puedo ayudar. — I can help.
• ¿Puedes venir? — Can you come?
• No puede correr. — She can’t run.

necesitar — to need

• Necesito estudiar. — I need to study.
• Necesitas descansar. — You need to rest.

deber — should / must

• Debo llegar temprano. — I should arrive early.
• Debes escuchar. — You should listen.

gustar — to like

• Me gusta hablar español. — I like to speak Spanish.
• Le gusta cocinar. — She likes to cook.

saber — to know how to

• Sé nadar. — I know how to swim.
• ¿Sabes cocinar? — Do you know how to cook?

Verb Phrases That Take the Infinitive

Beyond single verbs, several high-frequency verb phrases always take an infinitive after them. These are worth learning as complete chunks.

tener que + infinitive — to have to
Tengo que estudiar. — I have to study.
Tienes que comer. — You have to eat.
Tiene que llegar. — He has to arrive.

ir a + infinitive — going to (near future)
Voy a hablar con ella. — I’m going to speak with her.
Vas a aprender mucho. — You’re going to learn a lot.
Va a llover. — It’s going to rain.

acabar de + infinitive — to have just
Acabo de comer. — I just ate.
Acaba de llegar. — She just arrived.

empezar a + infinitive — to start to
Empiezo a entender. — I’m starting to understand.
Empieza a hablar. — He’s starting to speak.

volver a + infinitive — to do something again
Vuelvo a intentarlo. — I’m trying again.
Vuelve a llamar. — She’s calling again.

dejar de + infinitive — to stop doing
Dejo de fumar. — I’m stopping smoking.
Deja de hablar. — Stop talking.

These chunks are some of the most useful structures in everyday Spanish. Learn them as complete patterns — conjugated verb plus infinitive — and you have ready-made sentence frames for dozens of situations.

The Infinitive After Prepositions

Prepositions also trigger the infinitive in Spanish — another difference from English that trips learners up.

In English, a preposition is followed by a gerund: “before eating,” “after speaking,” “instead of going.”

In Spanish, a preposition is followed by the infinitive:

antes de + infinitive — before
Antes de comer, lavamos las manos. — Before eating, we wash our hands.

después de + infinitive — after
Después de estudiar, descansé. — After studying, I rested.

para + infinitive — in order to
Estudio para aprender. — I study in order to learn.
Trabajo para vivir. — I work to live.

sin + infinitive — without
Salió sin decir nada. — He left without saying anything.

al + infinitive — upon / when
Al llegar, llamé. — Upon arriving, I called.

These preposition plus infinitive combinations appear constantly in real Spanish. Recognizing them makes reading and listening significantly clearer.

Why This Matters From the Beginning

Most learners encounter the infinitive as a dictionary entry and move straight to conjugation without understanding what the infinitive actually does in real sentences. Then they hit phrases like Quiero comer or Tengo que ir and don’t understand why the second verb isn’t conjugated.

Understanding both jobs of the infinitive from the start prevents this confusion — and opens up dozens of useful sentence patterns immediately.

You can build real sentences with the infinitive on day one:

Quiero + infinitive — say what you want to do
Necesito + infinitive — say what you need to do
Tengo que + infinitive — say what you have to do
Voy a + infinitive — say what you’re going to do
Me gusta + infinitive — say what you like to do

Five frames. Any verb you know as an infinitive plugs straight in. That’s real Spanish production from the very beginning — before you’ve mastered a single conjugation pattern.

Closing Thoughts

The infinitive isn’t just a starting point for conjugation — it’s a working part of everyday Spanish that shows up in sentences you’ll use from day one.

English speakers who treat the infinitive as a dictionary-only form miss half of what it does. Quiero hablar. Tengo que estudiar. Después de comer. These aren’t advanced structures. They’re basic everyday Spanish built entirely on the infinitive.

Learn every new verb as an infinitive. Understand the stem it gives you. And start using it whole in the frames above — because the fastest path to real Spanish sentences runs directly through the infinitive.

Keep Going →

→ Spanish Verb Conjugation Explained Clearly — how the infinitive stem becomes a conjugated verb → Spanish Present Tense Verbs — the first conjugation pattern to build after understanding the infinitive → Spanish Sentence Patterns — the plug-and-play frames built on infinitives that you can use today