The Personal Infinitive in Portuguese — A Complete Guide — European Portuguese Guide

Understanding how to use the personal infinitive in Portuguese is one of the features that separates intermediate learners from truly advanced speakers and readers. The personal infinitive (infinitivo pessoal) is unique to Portuguese among major world languages — no other widely spoken language has it. It is an infinitive form that can be conjugated to agree with the subject in person and number. For learners of European Portuguese, it appears constantly in written and formal spoken registers, and understanding it is essential for reaching B2 and above.

What Is the Personal Infinitive?

Normally, an infinitive is impersonal — it does not indicate who is performing the action. In English: "to eat," "to go," "to speak." Portuguese also has an impersonal infinitive (comer, ir, falar). But Portuguese also has a personal infinitive that adds person-specific endings to show who is doing the action. The first person singular (eu) and third person singular (ele/ela) forms are identical to the impersonal infinitive — so in practice you only need to learn the additional endings for tu, nós, and eles/elas.

Person	Ending	falar	comer	partir
eu	(no ending)	falar	comer	partir
tu	-es	falares	comeres	partires
ele / ela	(no ending)	falar	comer	partir
nós	-mos	falarmos	comermos	partirmos
eles / elas	-em	falarem	comerem	partirem

Note: the first person singular (eu) and third person singular (ele/ela) are identical to the impersonal infinitive. In practice, you add an ending only for tu (-es), nós (-mos), and eles/elas (-em).

When to Use the Personal vs Impersonal Infinitive

Use PERSONAL infinitive when...	Use IMPERSONAL infinitive when...
The subject of the infinitive clause is DIFFERENT from the main clause subject	The subject of the infinitive is the SAME as the main clause
After prepositions when the subject needs to be explicit or differs	After modal verbs (devo, posso, quero) with same subject
To avoid ambiguity about who is performing the action	In set expressions and formulaic phrases
After para when the subjects differ: para eles virem	After antes de / depois de with same subject: antes de partir
After ao when subject needs clarification: ao chegarem	After por in passive constructions: foi feito por resolver

The core rule: when the subject performing the infinitive action is different from the subject of the main clause — or when you need to make the subject explicit — use the personal infinitive to clarify who is doing what.

8 Example Sentences with Analysis

"É importante estudarmos todos os dias." — It is important for us to study every day. (Personal: nós-form makes it clear that "we" must study.)
"Antes de saírem, apaguem as luzes." — Before they leave, they should turn off the lights. (Personal: eles-form — the instruction is addressed to a group.)
"Fui ao supermercado para comprar pão." — I went to the supermarket to buy bread. (Impersonal: same subject — I went, I buy.)
"Pedi-lhes para chegarem cedo." — I asked them to arrive early. (Personal: eles-form — I asked, but THEY arrive. Different subjects.)
"Ao chegares a casa, liga-me." — When you arrive home, call me. (Personal: tu-form after ao — makes it clear you are the one arriving.)
"É difícil falar português sem praticar." — It is difficult to speak Portuguese without practising. (Impersonal: no specific subject — generic statement.)
"Sem eles saberem, mudámos os planos." — Without them knowing, we changed the plans. (Personal: eles-form after sem — they are the ones not knowing, we changed.)
"Ao vermos o mar, ficámos emocionados." — Upon seeing the sea, we were moved. (Personal: nós-form after ao — we saw, we were moved — but the form still clarifies subject.)

After Which Prepositions Is the Personal Infinitive Used?

The personal infinitive is most commonly triggered by prepositions when the subjects differ between clauses or when clarity is needed:

para + personal infinitive: "para eles virem" (for them to come) — subjects differ
ao + personal infinitive: "ao chegarem" (upon their arriving) — identifies who is arriving
sem + personal infinitive: "sem eles saberem" (without them knowing) — different subject
antes de + personal infinitive: "antes de partires" (before you leave) — use personal when subject differs from main clause
depois de + personal infinitive: "depois de chegarem" (after they arrived) — identifies the arriving subject
por + personal infinitive: in some constructions, especially formal: "por serem diferentes" (for being different)

How This Differs from Brazilian Portuguese

The personal infinitive exists in Brazilian Portuguese (PT-BR) as well — it is not exclusive to EP — but it is used far less frequently in everyday Brazilian speech. Brazilian speakers tend to prefer subjunctive clauses or que-constructions where EP speakers naturally use the personal infinitive. As a result, when reading EP texts at B2 and above, you will encounter the personal infinitive very frequently. If your Portuguese input has been primarily Brazilian, the personal infinitive may feel unfamiliar even at B1-B2 level. This is one of the reasons dedicated EP study materials like PortuStories are important: they expose you to personal infinitive usage in natural context from the start.

Common Mistakes

Forgetting to inflect when subjects differ: "É bom os alunos estudar" ✗ — should be "É bom os alunos estudarem" ✓
Using personal infinitive when unnecessary (same subject): "Fui para eu comprar pão" — the eu is redundant here; "Fui comprar pão" is more natural. Using personal infinitive in same-subject contexts is not wrong but is usually redundant and sounds over-formal.
Confusing with future subjunctive: the tu future subjunctive (falares) and the tu personal infinitive (falares) are identical in form for regular verbs. Context determines which interpretation applies: future time clause (subjunctive) vs infinitive clause after preposition (personal infinitive).
Forgetting irregular infinitives: fazer, ser, ter, vir, trazer have irregular stem forms. fazeres, seres, teres, vieres, trazeres — make sure you are adding endings to the correct infinitive base.

Practice: B2 desenvolver story — C1 suscitar story