Portuguese verbs fall into three families by their infinitive ending: -ar, -er, and -ir. The -ir group is the smallest of the three, but it contains some of the most useful verbs in the language — partir, abrir, decidir, assistir. The good news for English speakers is that the regular -ir pattern is almost identical to the -er pattern you already know; there is exactly one form where they differ.
How it works
To conjugate a regular -ir verb in the present indicative, drop the -ir ending from the infinitive to get the stem, then add the ending that matches the subject.
The endings are: -o, -e, -imos, -em (plus regional -es for tu).
Unlike English, where the verb barely changes (I leave, you leave, he leaves), each Portuguese ending carries enough information to identify the subject on its own. This is why Brazilians often drop the subject pronoun in casual speech — the ending already tells you who is acting.
Partir — to leave / to depart
Let's use partir as our model. Drop -ir to get the stem part-, then add the endings.
| Subject | Conjugation |
|---|---|
| eu | parto |
| tu (regional) | partes |
| você / ele / ela | parte |
| nós | partimos |
| vocês / eles / elas | partem |
O trem parte às oito em ponto, então não se atrasa.
The train leaves at eight on the dot, so don't be late.
A gente parte amanhã de manhã pra praia.
We're leaving tomorrow morning for the beach.
Vocês partem hoje ou só na sexta?
Are you all leaving today or only on Friday?
The one difference from -er verbs
Here is the single fact that separates -ir from -er verbs in the present indicative: the nós form. Everything else is identical.
| Subject | -er (comer) | -ir (partir) |
|---|---|---|
| eu | como | parto |
| você / ele / ela | come | parte |
| nós | comemos | partimos |
| vocês / eles / elas | comem | partem |
The nós form of an -er verb ends in -emos; the nós form of an -ir verb ends in -imos. That vowel — the e versus the i — is the whole difference. Notice that the -ir nós form (partimos) keeps the i of the infinitive, so it is spelled identically to the simple past nós form. Brazilians rely on context to tell present from past here: Nós partimos amanhã (we leave tomorrow) versus Nós partimos ontem (we left yesterday).
Nós dividimos a conta entre os quatro, tá?
We split the bill among the four of us, okay?
A gente assiste àquela série toda quinta.
We watch that show every Thursday.
Common regular -ir verbs
These all follow the partir pattern. Learn the model and you get them for free.
| Infinitive | Meaning |
|---|---|
| abrir | to open |
| decidir | to decide |
| dividir | to divide, to split |
| garantir | to guarantee, to assure |
| assistir | to watch, to attend |
| discutir | to argue, to discuss |
| desistir | to give up |
| permitir | to allow |
A loja abre às nove e fecha às seis.
The store opens at nine and closes at six.
Eu garanto que ele vai gostar do presente.
I guarantee he'll like the gift.
Eles discutem por qualquer coisa, é cansativo.
They argue over anything, it's exhausting.
The preposition trap: assistir
One -ir verb deserves special attention because it behaves differently from its English counterpart. When assistir means "to watch" (a film, a game, a show), prescriptive grammar requires the preposition a before the object — you watch to something, structurally speaking.
Eu assisto a um filme toda sexta à noite.
I watch a movie every Friday night.
Vamos assistir ao jogo no bar?
Shall we go watch the game at the bar?
Notice the contractions: a + o = ao, a + a = à. So you say assistir ao jogo and assistir à novela. English has no equivalent — "watch" takes a direct object with no preposition, which is exactly why this is hard to remember.
Many -ir verbs are stem-changing
A large set of common -ir verbs are not fully regular: their eu form changes its stem vowel. For example, dormir becomes durmo (not "dormo"), and preferir becomes prefiro (not "prefero"). The vowel shifts only in the eu form; the other persons stay regular (você dorme, nós dormimos).
Eu durmo tarde, mas a minha irmã dorme cedo.
I sleep late, but my sister sleeps early.
This is a predictable, learnable pattern rather than random chaos. It is common enough that it gets its own page — see stem-changing -ir verbs for the full breakdown.
Common mistakes
❌ Nós partemos amanhã.
Incorrect — that's the -er ending; -ir verbs take -imos for nós.
✅ Nós partimos amanhã.
We leave tomorrow.
❌ Eu assisto o jogo. (in a formal essay)
Incorrect in formal writing — assistir 'to watch' requires the preposition a.
✅ Eu assisto ao jogo.
I watch the game.
❌ Eu dormo cedo durante a semana.
Incorrect — dormir is stem-changing, so the eu form is durmo.
✅ Eu durmo cedo durante a semana.
I sleep early during the week.
❌ Ela decidem ficar em casa.
Incorrect — singular subject needs the singular ending -e, not the plural -em.
✅ Ela decide ficar em casa.
She decides to stay home.
❌ Vocês abrem a janela? — written as 'vocês abre'.
Incorrect — vocês is plural and takes -em.
✅ Vocês abrem a janela?
Will you all open the window?
Once the regular -ir pattern feels automatic, the next step is the stem-changing -ir verbs, which build directly on what you've learned here.
Now practice Portuguese
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Start learning Portuguese→Related Topics
- Present Indicative: Regular -ar VerbsA1 — How to conjugate regular -ar verbs in the Brazilian Portuguese present indicative — plus the mandatory 'de' after gostar.
- Present Indicative: Regular -er VerbsA1 — How to conjugate regular -er verbs in the Brazilian Portuguese present indicative — and why so many common -er verbs are irregular.
- Stem-Changing -ir VerbsA2 — The predictable e→i and o→u vowel shift in the eu form of many Brazilian Portuguese -ir verbs, and why it reappears throughout the subjunctive.
- Present Indicative OverviewA1 — What the Brazilian Portuguese present indicative covers — and why it does the work English splits between simple and progressive.