Portuguese is the only major Romance language in which the infinitive can carry person endings — falar (to speak) becomes falarmos (for us to speak), falarem (for them to speak). After a preposition, this personal infinitive is the everyday Brazilian way to say "for someone to do something" when that someone is not the subject of the main verb. This page focuses on the most common trigger: prepositions like para, sem, antes de, depois de, and em vez de.
If you come from English, the closest equivalent is the awkward "for us to go" or "without them knowing." Portuguese folds the subject straight into the verb, which is far more compact — and once you hear it, sentences without it start to sound incomplete.
The core rule: who is doing the action?
The decision about whether to inflect the infinitive hinges on one question: does the infinitive clause have a subject different from the main verb?
- Different subject → use the personal infinitive (with its endings). This is strongly preferred and usually obligatory in careful speech.
- Same subject → in Brazilian Portuguese both the plain (impersonal) infinitive and the personal infinitive are acceptable.
É melhor para nós irmos agora, senão pegamos trânsito.
It's better for us to go now, otherwise we'll hit traffic.
Here the main clause is impersonal (é melhor) and the people going are nós — so irmos carries the -mos ending. Leaving it as ir would sound off to a Brazilian ear because nothing else in the sentence tells you who is going.
Antes de você chegar, já tinha arrumado tudo.
Before you arrived, I had already tidied everything up.
Para ele estudar mais, a gente vai cortar o videogame durante a semana.
For him to study more, we're going to cut out video games during the week.
The endings, briefly
The personal infinitive is built on the full infinitive (not a stem), so even irregular verbs are perfectly regular here. You add nothing for eu and ele/ela/você, and the rest take predictable endings:
| Subject | falar | comer | ir | sair |
|---|---|---|---|---|
| eu | falar | comer | ir | sair |
| você / ele / ela | falar | comer | ir | sair |
| nós | falarmos | comermos | irmos | sairmos |
| vocês / eles / elas | falarem | comerem | irem | saírem |
Note the accent on saírem: the stressed í of sair-type verbs keeps its written accent in the -em form (saírem, caírem), just as it does in other forms of these verbs. For full paradigms and the -mos/-em/-des details, see Forming the Personal Infinitive.
Para — "for someone to do"
The most important pattern for learners is para + personal infinitive. In Brazilian Portuguese this is the unmarked, neutral way to express purpose or "for X to do Y" — it is not formal, not literary, just normal.
É importante para nós sairmos cedo amanhã.
It's important for us to leave early tomorrow.
Comprei um livro para as crianças lerem nas férias.
I bought a book for the kids to read over the holidays.
Deixa a janela aberta para o ar circular.
Leave the window open for the air to circulate.
Notice the last example: o ar is third-person singular, so the infinitive stays circular with no ending — the personal infinitive's "ending" for ele/ela is simply zero. The construction is still a personal infinitive (it has its own subject), it just happens to look identical to the plain infinitive in the singular.
Sem, antes de, depois de, até
These prepositions work the same way. When the infinitive clause has its own subject, inflect.
Sem eles saberem, organizamos uma festa surpresa.
Without them knowing, we organized a surprise party.
Depois de vocês entrarem, a porta tranca sozinha.
After you (all) come in, the door locks by itself.
Eles foram embora sem se despedirem.
They left without saying goodbye.
In the last sentence the subject of the infinitive (eles) is the same as the main verb, so Brazilian Portuguese allows either despedir or despedirem. The inflected form is common because the plural is clearly marked and sounds careful and natural.
Em vez de / ao invés de
These mean "instead of." They frequently introduce a contrasting subject, which makes the personal infinitive especially useful.
Em vez de elas saírem, ficaram em casa vendo série.
Instead of going out, they stayed home watching a show.
Ao invés de a gente discutir, vamos resolver isso conversando.
Instead of us arguing, let's sort this out by talking.
A note on a gente: it means "we" but grammatically behaves as third-person singular, so it pairs with the uninflected form (discutir, not discutirmos). This trips up many learners — see the mistakes section below.
Same subject: your choice
When the infinitive shares its subject with the main clause, Brazilian Portuguese gives you a genuine choice, and both options are correct standard usage.
Estudamos muito para passarmos na prova.
We studied a lot to pass the exam.
Estudamos muito para passar na prova.
We studied a lot to pass the exam.
Both are fine. The inflected version (passarmos) is slightly more explicit and is often favored in writing and careful speech; the plain version (passar) is lighter and extremely common in casual conversation. There is no meaning difference. Prescriptive grammars sometimes claim the plain infinitive is "better" with a shared subject, but in real Brazilian usage the inflected form is fully accepted and often preferred for clarity.
Why Portuguese does this — and English can't
English marks the subject of an infinitive with a separate word: for us to leave, without them knowing, for him to study. The pronoun (us, them, him) sits outside the verb. Portuguese instead bakes the subject information into the verb ending itself, which is why irmos needs no extra pronoun to mean "for us to go" — though Brazilians often include nós anyway for emphasis or clarity.
This is genuinely unique. Spanish and French simply cannot inflect the infinitive: Spanish says para que salgamos (subjunctive) or para salir (ambiguous as to subject), and French says pour que nous partions. Portuguese's personal infinitive lets you keep the lightness of an infinitive while still pinning down exactly who acts — a tool the other Romance languages lack entirely. This is also why the personal infinitive so often replaces subjunctive clauses, a topic covered in Personal Infinitive Replacing Subjunctive Clauses.
Common Mistakes
English speakers make a predictable set of errors here, mostly from carrying over English structure or from under-using the inflection.
❌ É melhor para nós ir agora.
Incorrect — the subject is nós, so the infinitive must inflect to irmos.
✅ É melhor para nós irmos agora.
It's better for us to go now.
❌ Sem eles saber, fizemos a festa.
Incorrect — eles is plural, so the infinitive must be saberem.
✅ Sem eles saberem, fizemos a festa.
Without them knowing, we threw the party.
❌ Para nós passarmos, a gente estudarmos muito.
Incorrect — a gente is grammatically third-person singular and does NOT take -mos.
✅ Para nós passarmos, a gente estudou muito.
For us to pass, we studied a lot.
❌ Comprei o livro para as crianças lerto.
Incorrect invented form — the third-person plural personal infinitive of ler is lerem.
✅ Comprei o livro para as crianças lerem.
I bought the book for the children to read.
❌ Antes de eles chegarem, eu arrumarem a casa.
Incorrect — the second clause's subject is eu, which takes no ending: arrumar/arrumei, never arrumarem.
✅ Antes de eles chegarem, eu arrumei a casa.
Before they arrived, I tidied the house.
The recurring theme: the ending must match the subject of that specific infinitive. Don't copy the ending from a nearby clause, and remember that a gente and você both pattern with the unmarked singular form.
Key Takeaways
- After a preposition, inflect the infinitive when its clause has its own subject — especially with nós (-mos) and eles/elas/vocês (-em).
- Para
- personal infinitive is the everyday Brazilian way to say "for someone to do something." It is not formal.
- With a shared subject, both the plain and inflected infinitive are correct; the choice is stylistic.
- Eu and você/ele/ela take no ending, so the personal infinitive looks like the plain infinitive in the singular — but it's still a personal infinitive.
- Watch out for a gente (= "we" in meaning, but third-person singular in grammar): it never takes -mos.
Now practice Portuguese
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Start learning Portuguese→Related Topics
- The Personal Infinitive: OverviewB1 — Portuguese's signature feature — an infinitive that carries person and number endings, letting infinitive clauses take their own subject.
- Forming the Personal InfinitiveB1 — How to build the personal infinitive — the infinitive plus uniform person endings — and why even irregular verbs are perfectly regular here.
- The Infinitive in BR PortugueseA2 — Brazilian Portuguese has two infinitives — the regular (impersonal) one and a unique personal infinitive that carries person endings.
- Personal vs Impersonal InfinitiveB1 — How to decide whether to leave the infinitive bare or inflect it for person — the rule turns on whether the infinitive has its own, distinct subject.
- Personal Infinitive in Subject ClausesB2 — How the personal infinitive serves as the subject of impersonal evaluative clauses like é importante, é difícil, and não é justo.