The Regular (Impersonal) Infinitive | Portuguese (Brazil) Grammar

The regular infinitive is the form you'll meet first and use constantly: the plain dictionary form of the verb. Every Brazilian Portuguese verb ends in -ar, -er, or -ir in this form — falar (to speak), comer (to eat), partir (to leave). It never changes for person, number, or tense. It's "impersonal" precisely because it has no subject of its own; it leans on the verb or preposition next to it. This page covers the five places it shows up, and one habit English and Spanish speakers need to unlearn.

What it looks like

There are only three endings, matching the three verb classes:

Class	Infinitive	Meaning
-ar	falar, trabalhar, gostar	to speak, to work, to like
-er	comer, beber, vender	to eat, to drink, to sell
-ir	partir, abrir, dormir	to leave, to open, to sleep

The class is taught in full on The three conjugation classes. For now, just notice the three endings — they're how you'll recognize an infinitive on sight.

When one verb governs another, the second verb goes in the infinitive. This is the single most common use. The key Brazilian fact: there is no preposition between them. You say the modal, then the bare infinitive.

Eu quero comer agora.

I want to eat now.

Você pode entrar, a porta está aberta.

You can come in, the door's open.

Vou estudar à noite, hoje estou cansada.

I'm going to study tonight, I'm tired today.

The verb ir (to go) + infinitive is the everyday way Brazilians talk about the future — vou estudar, vamos comer, ele vai chegar tarde. There's more on this at The periphrastic future.

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Brazilian Portuguese uses a bare infinitive after these verbs — no linking word. This trips up Spanish speakers, who say voy A comer, and French speakers, who say aller manger. In Portuguese it's just vou comer, quero comer, preciso comer. Drop the "a."

Use 2: After prepositions

When a preposition is followed by a verb, that verb appears in the infinitive — never in an "-ing" form the way English does. This is one of the cleanest contrasts with English, which uses the gerund after prepositions ("before eating," "without speaking").

Lava as mãos antes de comer.

Wash your hands before eating.

Ele saiu sem falar com ninguém.

He left without speaking to anyone.

Em vez de ir de carro, vamos a pé.

Instead of going by car, let's walk.

Note that the preposition itself doesn't change: antes de, sem, em vez de are followed directly by the plain infinitive. (When such a clause has its own subject, the infinitive can inflect — that's the personal infinitive, covered separately.)

Use 3: In instructions, recipes, and signs

Brazilian Portuguese uses the bare infinitive for impersonal instructions — the tone of a recipe or a public notice. It's like English "Bake for 20 minutes" or "Do not lean on the door."

Lavar bem o frango e temperar com sal e limão.

Wash the chicken well and season with salt and lime.

Bater os ovos e acrescentar a farinha aos poucos.

Beat the eggs and add the flour little by little.

Não fumar.

No smoking. (a sign)

This register is genuinely useful: every recipe you read in Portuguese will be written this way, in a string of infinitives.

Use 4: As a noun

The infinitive can be the subject or object of a sentence — Portuguese's equivalent of the English "-ing" gerund used as a noun ("Smoking is bad"). The Portuguese infinitive simply is the noun.

Comer demais faz mal.

Eating too much is bad for you.

Viajar sozinha me ensinou muita coisa.

Traveling alone taught me a lot.

O importante é tentar.

The important thing is to try.

You can even put the definite article in front of it to make it fully nominal: o comer, o viver, o saber — though this is a more literary flavor.

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Where English chooses between "to eat" and "eating" depending on the slot, Portuguese uses the same infinitive for both. Comer demais faz mal = "Eating too much is bad," and Quero comer = "I want to eat." One form, two English translations.

Use 5: After "ter que," "dever," "precisar"

The common verbs of obligation and need all take a following infinitive. Ter que (to have to) and precisar are the everyday workhorses; dever (should / ought to) is slightly more formal.

Eu tenho que sair daqui a pouco.

I have to leave in a little while.

Você precisa descansar mais.

You need to rest more.

A gente deve avisar o chefe antes.

We ought to let the boss know first.

Note ter que (informal, everyday) versus ter de (formal/written) — they mean the same thing, and ter que dominates in speech. Precisar can optionally take de before a noun (preciso de ajuda) but takes a bare infinitive before a verb (preciso descansar).

Common Mistakes

Almost every error here comes from importing an English "-ing" or a Spanish/French linking "a."

❌ Eu vou a comer agora.

Incorrect — no 'a' after a modal. (Spanish interference: 'voy a comer')

✅ Eu vou comer agora.

I'm going to eat now.

❌ Antes de comendo, lava as mãos.

Incorrect — Portuguese uses the infinitive after a preposition, not the gerund.

✅ Antes de comer, lava as mãos.

Before eating, wash your hands.

❌ Fumando faz mal à saúde.

Incorrect — as a noun-subject, Portuguese uses the infinitive, not the gerund.

✅ Fumar faz mal à saúde.

Smoking is bad for your health.

❌ Eu preciso de descansar.

Incorrect before a verb — 'precisar de' takes a noun, but a bare infinitive before a verb.

✅ Eu preciso descansar.

I need to rest.

❌ Você pode de entrar?

Incorrect — 'poder' takes a bare infinitive with no preposition.

✅ Você pode entrar?

Can you come in?

Key Takeaways

The regular infinitive is the unchanging dictionary form ending in -ar / -er / -ir.
After modals (querer, poder, ir, dever, precisar, ter que), use a bare infinitive — no "a," no "de" before the verb.
After prepositions (antes de, sem, em vez de), Portuguese uses the infinitive, where English uses "-ing."
The infinitive doubles as a noun (fumar faz mal) and as the form for recipes and signs (lavar bem o frango).
Unlearn the Spanish/French linking word: it's vou comer, not vou a comer.

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