The Three Conjugation Classes (-ar, -er, -ir) | Portuguese (Brazil) Grammar

Every Brazilian Portuguese verb belongs to exactly one of three conjugation classes, and you can tell which one just by looking at the last two letters of the infinitive: -ar, -er, or -ir. The class determines which set of endings the verb takes across all tenses. Learning to spot the class on sight is the foundation of everything that follows, because once you know the class, you know the default pattern.

The infinitive is the dictionary form

First, a point that surprises English speakers. The infinitive — falar, comer, partir — is a single word. English splits its infinitive into two: "to speak," "to eat," "to leave." Portuguese fuses the "to" into the verb itself.

Quero falar com você um minuto.

I want to speak with you for a minute.

É difícil comer só uma.

It's hard to eat just one.

There is no separate word for "to" here. Falar alone means "to speak." This means that whenever your English sentence has "to + verb," you usually want a bare Portuguese infinitive, not two words.

The three classes at a glance

Class	Ending	Size	Examples
1ª conjugação	-ar	by far the largest	falar, trabalhar, estudar, gostar
2ª conjugação	-er	smaller, often irregular	comer, beber, vender, escrever
3ª conjugação	-ir	medium, fairly regular	partir, abrir, decidir, dormir

First conjugation: -ar (the giant)

The -ar class contains the overwhelming majority of Portuguese verbs and is the most regular. Here is falar (to speak) in the present indicative:

Subject	falar
eu	falo
você / ele / ela	fala
nós	falamos
vocês / eles / elas	falam

Eu trabalho de casa três dias por semana.

I work from home three days a week.

A gente estuda junto pra prova de amanhã.

We're studying together for tomorrow's test.

Crucially, the -ar class is the only productive class — the only one still accepting new members. Every borrowing and coinage in modern Brazilian Portuguese lands here:

New verb	From	Means
deletar	"delete"	to delete
printar	"print/screen"	to screenshot
postar	"post"	to post (online)
googlar	"google"	to google
tuitar	"tweet"	to tweet

Eu já printei a conversa, fica tranquilo.

I already screenshotted the conversation, don't worry.

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If you ever need a verb you don't know, and it comes from English or is freshly invented, conjugate it as an -ar verb. You'll be right far more often than not — the -er and -ir classes are essentially closed to newcomers.

Second conjugation: -er

The -er class is smaller and harbors many of the language's most common irregular verbs (ser, ter, fazer, poder, querer are all -er and all irregular). But the regular pattern, modeled on comer (to eat), is clean:

Subject	comer
eu	como
você / ele / ela	come
nós	comemos
vocês / eles / elas	comem

Ele come muito pouco de manhã.

He eats very little in the morning.

Vocês bebem café ou chá?

Do you all drink coffee or tea?

Third conjugation: -ir

The -ir class is medium-sized and reasonably regular, though it includes some stem-changing verbs (like dormir → durmo). The model is partir (to leave / to depart):

Subject	partir
eu	parto
você / ele / ela	parte
nós	partimos
vocês / eles / elas	partem

O trem parte às sete em ponto.

The train leaves at seven on the dot.

A gente decide isso na reunião.

We'll decide that in the meeting.

-er and -ir are almost the same

Here is the most useful observation for a beginner. In the present indicative, the -er and -ir classes are identical except in a single slot — the nós form:

Subject	comer (-er)	partir (-ir)	Same?
eu	como	parto	same ending (-o)
você / ele / ela	come	parte	same ending (-e)
nós	comemos	partimos	differ (-emos vs -imos)
vocês / eles / elas	comem	partem	differ (-em vs -em — actually same!)

In practice the only present-tense form that reliably separates the two classes is nós: comemos (e) versus partimos (i). The theme vowel of the infinitive (-e- vs -i-) survives most clearly there. In other tenses, such as the imperfect (comia / partia), the two classes merge completely. This is why many learners treat -er and -ir as one big "second-and-third" group with a single tweak.

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Drilling the present tense? Focus your -er-vs--ir energy on the nós form. Comemos vs partimos is essentially the only spot where the two classes diverge in the present.

Nós comemos fora todo sábado.

We eat out every Saturday.

Nós partimos cedo para evitar o trânsito.

We leave early to avoid traffic.

How to use the class

When you meet a new verb, your first move is to read the ending and assign it a class. That single act predicts its entire conjugation, unless the verb is flagged irregular. The dedicated pages drill each class in full:

First conjugation: -ar verbs
Second conjugation: -er verbs
Third conjugation: -ir verbs

Common mistakes

❌ Quero to falar com você.

Incorrect — Portuguese has no separate 'to'; the infinitive already includes it.

✅ Quero falar com você.

I want to speak with you.

❌ Nós comimos fora todo sábado. (meaning a present habit)

Incorrect for the present — 'comimos' is the preterite; the present nós form is 'comemos'.

✅ Nós comemos fora todo sábado.

We eat out every Saturday.

❌ Nós partemos cedo.

Incorrect — -ir verbs take -imos in the nós present, not -emos.

✅ Nós partimos cedo.

We leave early.

❌ Eu deleto o arquivo? Não, eu deletes.

Incorrect — borrowed verbs join the regular -ar class; eu form is 'deleto'.

✅ Eu deleto o arquivo.

I'll delete the file.

Key takeaways

Three classes by infinitive ending: -ar (largest, most regular, only productive class), -er (smaller, many irregulars), -ir (medium, fairly regular).
The infinitive is one word and already contains the English "to."
New and borrowed verbs always join -ar (deletar, postar, googlar).
In the present, -er and -ir differ reliably only in the nós form (comemos vs partimos).

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