Portuguese Preposition 'Por': Expressing Cause & Reason
por to explain the 'why' behind things, looking back at the cause, reason, or original motivation.
Grammar Rule in 30 Seconds
Use 'por' to explain the cause, motive, or reason behind an action or situation.
- Use 'por' for the cause of an event: 'Não saí por causa da chuva.'
- Use 'por' for motivation or incentive: 'Fiz isso por você.'
- Use 'por' for exchange or substitution: 'Troquei o livro por um filme.'
Overview
The Portuguese preposition por is fundamental for expressing cause, reason, motive, and origin. It functions as a versatile link, explaining the 'why' behind actions, states, or emotions. Unlike English, which employs several prepositions and conjunctions such as 'for', 'because of', 'due to', 'by', or 'through', Portuguese frequently consolidates these meanings into por.
Understanding por is crucial for B1 learners, as it clarifies the impetus for events, distinguishing it from para, which focuses on purpose or destination.
At its core, por signifies a backward-looking relationship: it indicates the antecedent, the stimulus, or the source that prompts a subsequent action or state. This contrasts sharply with para, which implies a forward-looking orientation toward a goal or outcome. Mastering this distinction allows for precise communication regarding motivations and origins.
How This Grammar Works
por establishes a connection between an action or state and its underlying cause or reason. Its usage varies depending on whether it precedes a noun, a pronoun, or an infinitive verb, and it frequently combines with definite articles.Por + Noun/Pronoun: This is the most direct way to express cause. The noun or pronoun following por identifies the direct reason or stimulus for the preceding action or feeling.A cidade foi destruída por um terramoto.(The city was destroyed by an earthquake.) Here,um terramotois the cause of destruction.Sinto uma grande admiração por ele.(I feel great admiration for him.) The person (ele) is the object of the admiration.Fui multado por estacionamento proibido.(I was fined for illegal parking.) The illegal parking is the reason for the fine.
Por causa de: This compound expression explicitly translates to 'because of' or 'on account of'. While often interchangeable with por in causal contexts, por causa de provides a more emphatic or formal declaration of causality. It is commonly used when the reason is a specific event or circumstance.Cancelámos a viagem por causa da chuva.(We canceled the trip because of the rain.)Ele atrasou-se por causa do trânsito.(He was late because of the traffic.)
Por + Infinitive Verb: When por is followed by an infinitive verb, the action expressed by that verb is identified as the reason or cause for the main clause. This construction is highly prevalent and essential for B1 fluency.Parabenizo-o por ter concluído o projeto.(I congratulate him for having completed the project.) The act of completing the project is the reason for the congratulation.Peço desculpa por chegar atrasado.(I apologize for arriving late.) The act of arriving late is the reason for the apology.
Por is consistently used to introduce the source or object of various emotions, perceptions, or internal states. It specifies what elicits the feeling or thought.Estou feliz por você ter conseguido.(I am happy for you having succeeded.) Your success is the reason for my happiness.Tenho grande carinho pelos meus avós.(I have great affection for my grandparents.) My grandparents are the object of my affection.Ele sofre pela saudade da família.(He suffers from longing for his family.) The longing is the cause of his suffering.
por acts as a crucial indicator of the origin or stimulus, directing the listener or reader to the foundational element of the statement.Formation Pattern
por frequently contracts with definite articles (o, a, os, as) that immediately follow it. This agglutination is a mandatory grammatical feature in standard Portuguese and affects how por is pronounced and written. The resulting contractions are pelo, pela, pelos, and pelas. These forms are not optional and neglecting them is a common error for learners.
per, which merged with the articles to form per-o, per-a, etc. Over time, per evolved into por, but the 'l' sound from the article's merger was retained in the contracted forms. This linguistic evolution explains the presence of the 'l' that may seem irregular at first glance.
por | o -> pelo | a -> pela | os -> pelos | as -> pelas |
Ele foi elogiado pelo seu esforço. (He was praised for his effort.) - por + o (esforço is masculine singular)
Ela está preocupada pela demora. (She is worried about the delay.) - por + a (demora is feminine singular)
Passamos pelos campos a caminho de casa. (We passed through the fields on the way home.) - por + os (campos is masculine plural)
Caminhámos pelas ruas da cidade. (We walked through the city streets.) - por + as (ruas is feminine plural)
por does not contract with indefinite articles (um, uma, uns, umas) or with demonstrative pronouns (este, esse, aquele, etc.). In such cases, por remains separate.
Fizemos uma pausa por um momento. (We took a break for a moment.)
Votei nele por um ideal. (I voted for him for an ideal.)
When To Use It
Por is employed in a variety of contexts to express cause, reason, means, duration, and exchange. For B1 learners, understanding these core applications is essential for accurate communication.- 1Expressing Cause or Reason: This is the primary function addressed in this chapter.
Porindicates the motivation, stimulus, or origin of an action, state, or emotion.
Fico feliz pelo seu sucesso.(I am happy for your success.)Não fui ao trabalho por estar doente.(I didn't go to work because of being sick.)Ele agiu por desespero.(He acted out of desperation.)
- 1Agent in Passive Voice: In passive constructions,
porintroduces the agent who performs the action. This is a critical grammatical function.
O livro foi escrito por um autor famoso.(The book was written by a famous author.)A decisão será anunciada pelo presidente.(The decision will be announced by the president.)
- 1Motive or Motivation:
Porhighlights the underlying drive or incentive for an action, often relating to personal gain, principle, or emotion.
Ela trabalha muito pela sua família.(She works hard for her family.)Lutamos pela liberdade.(We fight for freedom.)
- 1Exchange or Substitution: This usage indicates that something is given or received in place of something else, or a price paid for an item.
Troquei meu carro velho por um novo.(I exchanged my old car for a new one.)Paguei vinte euros pelo ingresso.(I paid twenty euros for the ticket.)
- 1Duration (Approximation or Distribution): While
porcan indicate the approximate duration of an action (especially in European Portuguese), it more commonly expresses frequency or distribution 'per' a unit of time or measure in both varieties.
Ele estuda três horas por dia.(He studies three hours per day.)Custa dez euros por quilo.(It costs ten euros per kilo.)- In European Portuguese:
Esperei por uma hora.(I waited for an hour.) In Brazilian Portuguese, the preposition is often omitted in this context:Esperei uma hora.
- 1Means or Method:
Porspecifies the channel, medium, or method through which an action is performed, particularly with communication or transportation.
Contactei-o por email.(I contacted him by email.)Viajamos pelo comboio.(We traveled by train.)
- 1Movement Through or Along a Space: This denotes movement across, through, or along a physical space. It signifies traversing a path or area.
Passamos por Lisboa a caminho do Porto.(We passed through Lisbon on the way to Porto.)Caminhamos pela praia ao pôr do sol.(We walked along the beach at sunset.)
Common Mistakes
por. Recognizing and addressing these patterns is vital for accurate expression.- 1Confusing
PorandPara: This is arguably the most common and persistent error. The distinction lies in their inherent directionality.Porrefers to the cause, origin, or means (looking backward at the stimulus), whileparaindicates purpose, destination, or recipient (looking forward to the goal).
- Incorrect:
Estudo para prazer.(Implies pleasure is a destination.) - Correct:
Estudo por prazer.(Pleasure is the reason for studying.) - Incorrect:
Trabalho por uma vida melhor.(Suggests a better life is the source.) - Correct:
Trabalho para uma vida melhor.(A better life is the purpose or goal.)
- 1Omitting Contractions (
Pelo,Pela,Pelos,Pelas): Failing to contractporwith definite articles is a grammatical error that makes speech sound unnatural and ungrammatical. Unlike some informal contexts where contractions might be less rigid, standard Portuguese demands these contractions.
- Incorrect:
Ele saiu por a porta. - Correct:
Ele saiu pela porta.(He exited through the door.) - Incorrect:
Fui acordado por o barulho. - Correct:
Fui acordado pelo barulho.(I was woken up by the noise.)
- 1Mixing
PorandPorque: These two terms, despite their similar sound and related meanings, function differently in a sentence.Poris a preposition, followed by a noun, pronoun, or infinitive verb.Porqueis a conjunction, introducing a clause (which contains a subject and a conjugated verb) to explain a reason.
Por preguiça, não fiz o trabalho.(Due to laziness, I didn't do the work.) -preguiça(laziness) is a noun.Não fiz o trabalho porque estava com preguiça.(I didn't do the work because I was lazy.) -estava com preguiçais a clause.- Incorrect:
Fiz isso por eu te amo. - Correct:
Fiz isso porque eu te amo.(I did that because I love you.)
- 1Misusing
Porfor Formal Causality: Whileporexpresses cause, in more formal or academic contexts, or when emphasizing an inherent reason, other expressions likedevido a('due to') orgraças a('thanks to') are often preferred. Usingporin such situations might sound too informal or less precise.
- Less formal:
Perdemos o voo por o atraso. - More appropriate:
Perdemos o voo devido ao atraso.(We missed the flight due to the delay.) - Less precise:
Conseguimos por a sua ajuda. - More appropriate:
Conseguimos graças à sua ajuda.(We succeeded thanks to your help.)
Real Conversations
Understanding how por is used in everyday, authentic communication is essential for B1 learners to sound natural and integrate into Portuguese-speaking environments. Its presence is ubiquitous across various registers, from casual texting to formal correspondence.
Informal & Texting: In casual settings, especially among younger speakers, por appears frequently in clipped phrases or as part of common expressions.
- Atrasado por causa do bus. (Late because of the bus.) - A common excuse, often shortened.
- Vou passar aí pelas 5. (I'll stop by around 5.) - Indicating approximation of time.
- Obrigado por me ouvires, mano. (Thanks for listening to me, bro.) - Expressing gratitude with informal address.
Work & Formal Correspondence: In professional emails or more formal discussions, por maintains its precise grammatical functions, particularly in explaining reasons or attributing actions.
- Lamentamos qualquer inconveniente causado pela alteração de horário. (We regret any inconvenience caused by the schedule change.)
- A proposta foi aprovada por unanimidade. (The proposal was approved by unanimity.)
- A reunião foi adiada por motivo de força maior. (The meeting was postponed due to force majeure.)
Social Media & Public Discourse: On social platforms or in news reports, por is used to attribute opinions, describe emotional responses, or explain widespread phenomena.
- Grato por cada momento. (Grateful for every moment.) - A common expression of thankfulness.
- Manifestantes marcharam pela justiça social. (Protesters marched for social justice.) - Indicating the motive or cause of the action.
- Fui surpreendido pelo resultado da eleição. (I was surprised by the election result.) - Attributing the cause of a personal reaction.
Cultural Insight
por favor (please) is a prime example of por expressing motive. It literally means 'by favor' or 'as a favor', implying that an action is requested based on goodwill or as a courtesy. This reflects a cultural emphasis on polite social interaction. Similarly, porreiro (EP, cool/awesome) or porra (BP, an expletive) demonstrate how por can be integral to common interjections, even if its original meaning is obscured.Quick FAQ
por causa de when I want to express 'because of'?While por causa de is a reliably explicit way to convey 'because of', over-reliance on it can make your Portuguese sound less natural. Native speakers frequently use por directly with nouns or infinitives. Varying your usage demonstrates greater fluency and understanding of nuance.
por ever mean 'for' in the sense of duration?Yes, por can indicate duration, but there is a notable difference between European Portuguese (EP) and Brazilian Portuguese (BP). In EP, por is commonly used: Esperei por duas horas. (I waited for two hours.) In BP, the preposition is often omitted in this context: Esperei duas horas. However, por is consistently used in both varieties for frequency or distribution: Três vezes por semana. (Three times per week.)
por que, porque, porquê, and por quê?This is a complex aspect of Portuguese, especially for B1 learners. All relate to 'why' or 'because', but their usage depends on context:
Por que(separated, no accent): Used in questions (Por que não vens?- Why aren't you coming?) or whenquecan be replaced bypelo qual/pela qual(e.g., relative clauses:Esta é a razão por que me atrasei.- This is the reason why I was late).Porque(together, no accent): Used as a conjunction in affirmative answers or statements, meaning 'because'.Não fui porque estava doente.(I didn't go because I was sick.)Porquê(together, with accent): A noun, meaning 'the reason' or 'the motive', often preceded by an article:Não sei o porquê da sua decisão.(I don't know the reason for his decision.) It can also appear at the end of a sentence or before a pause:Ele não veio, e eu não sei porquê.(He didn't come, and I don't know why.)Por quê(separated, with accent): Used at the end of a question, before a punctuation mark:Ele não veio por quê?(Why didn't he come?)
por telefone or pelo telefone?Both are generally acceptable, with a subtle difference in emphasis. Por telefone typically denotes the general method or means of communication ('by phone'). Pelo telefone (contraction of por + o telefone) places a slightly greater emphasis on the specific medium or device through which the communication occurs, implying 'through the phone'. In most daily contexts, they are interchangeable, but por telefone is slightly more common for the general means.
por favor?Por favor directly translates to 'by favor' or 'as a favor'. When you use this expression, you are essentially asking someone to perform an action motivated by goodwill, kindness, or as a courtesy extended to you. It beautifully encapsulates the essence of por as expressing the underlying reason or motive for an action – in this case, the motivation of a favor.
Contractions of 'Por'
| Preposition | Article | Resulting Form |
|---|---|---|
|
por
|
o
|
pelo
|
|
por
|
a
|
pela
|
|
por
|
os
|
pelos
|
|
por
|
as
|
pelas
|
Common Contractions
| Form | Usage |
|---|---|
|
pelo
|
masculine singular
|
|
pela
|
feminine singular
|
|
pelos
|
masculine plural
|
|
pelas
|
feminine plural
|
Meanings
The preposition 'por' is used to indicate the cause, motive, or reason for an action, as well as the agent of a passive voice construction.
Cause/Motive
Explaining why something happened.
“Chorei por alegria.”
“Ele não veio por doença.”
Exchange
Trading one thing for another.
“Troquei o carro por uma moto.”
“Paguei dez reais por este café.”
Agent of Passive Voice
Who performed the action in a passive sentence.
“O livro foi escrito por Machado de Assis.”
“A casa foi pintada por eles.”
Reference Table
| Form | Structure | Example |
|---|---|---|
|
Affirmative
|
Subject + Verb + por + Cause
|
Fiz por você.
|
|
Negative
|
Subject + não + Verb + por + Cause
|
Não fiz por medo.
|
|
Question
|
Por + que + Verb + Subject?
|
Por que você fez isso?
|
|
Passive
|
Object + ser + Participle + por + Agent
|
Foi feito por mim.
|
|
Exchange
|
Verb + Object + por + Object
|
Troquei por outro.
|
|
Idiomatic
|
Por + Noun
|
Por acaso.
|
Formality Spectrum
Realizei tal feito por sua causa. (Favor)
Fiz isso por você. (Favor)
Fiz por ti. (Favor)
Fiz por você, mano. (Favor)
The Many Faces of Por
Cause
- por medo out of fear
Exchange
- trocar por trade for
Agent
- feito por made by
Examples by Level
Estou aqui por você.
I am here for you.
Obrigado por tudo.
Thanks for everything.
Não saí por causa da chuva.
I didn't go out because of the rain.
Fiz isso por amor.
I did this for love.
Troquei o livro pelo filme.
I traded the book for the movie.
Paguei dez reais pela maçã.
I paid ten reais for the apple.
A casa foi pintada pelos homens.
The house was painted by the men.
Andamos pelas ruas.
We walked through the streets.
A decisão foi tomada por nós.
The decision was made by us.
Ele foi elogiado pelo professor.
He was praised by the teacher.
Não pude ir por motivos de saúde.
I couldn't go for health reasons.
Lutamos por nossos direitos.
We fight for our rights.
Por acaso, você viu meu celular?
By chance, did you see my phone?
Por fim, chegamos a um acordo.
Finally, we reached an agreement.
O projeto foi aprovado pela diretoria.
The project was approved by the board.
Ele foi reconhecido pelo seu trabalho.
He was recognized for his work.
Por mais que eu tente, não consigo.
No matter how much I try, I can't.
A obra foi aclamada pela crítica especializada.
The work was acclaimed by the specialized critics.
Por conseguinte, a medida foi revogada.
Consequently, the measure was revoked.
Ele agiu por impulso.
He acted on impulse.
Porventura, estarias interessado em participar?
By any chance, would you be interested in participating?
A lei foi sancionada pelo poder executivo.
The law was sanctioned by the executive branch.
Por entre as árvores, via-se o sol.
Through the trees, one could see the sun.
Foi por mim que a verdade foi revelada.
It was by me that the truth was revealed.
Easily Confused
Both can mean 'for' in English.
Both sound the same.
Learners forget to contract.
Common Mistakes
Eu faço isso para você (meaning because of you)
Eu faço isso por você
Por o
Pelo
Por que (as a conjunction)
Porque
Eu vou por a escola
Eu vou para a escola
Paguei por o livro
Paguei pelo livro
A casa foi feita para ele (passive)
A casa foi feita por ele
Estou aqui para causa de você
Estou aqui por causa de você
Ele foi elogiado para o chefe
Ele foi elogiado pelo chefe
Por fim de contas
Por fim / No fim das contas
Ele agiu por o impulso
Ele agiu por impulso
Por mais que eu tento
Por mais que eu tente
A lei foi aprovada para o governo
A lei foi aprovada pelo governo
Ele foi reconhecido para seu trabalho
Ele foi reconhecido pelo seu trabalho
Sentence Patterns
Eu fiz isso ___ ___.
O livro foi escrito ___ ___.
Troquei o carro ___ ___.
___ ___ você está aqui?
Real World Usage
Obrigado por seguir!
Estou aqui por interesse na vaga.
Vou por você.
Paguei pelo aplicativo.
Andamos pela cidade.
A lei foi aprovada pelo congresso.
The 'Para' Test
Don't forget contractions
Passive Voice
Regional variation
Smart Tips
Use 'por causa de' if you want to be very clear.
Always check if you need a contraction.
Use two words for questions.
Use 'trocar por'.
Pronunciation
Stress
The word 'por' is a monosyllable and is usually unstressed unless emphasized.
Causal emphasis
Fiz isso POR você! (rising on POR)
Emphasizing the reason.
Memorize It
Mnemonic
POR: Purpose of Origin, Reason, or Exchange.
Visual Association
Imagine a scale. On one side, you put a cause (like a heavy stone), and on the other, the result. The scale is held together by the word 'POR'.
Rhyme
Se a causa você quer explicar, a palavra 'por' deve usar.
Story
Maria was sad. She cried 'por' (because of) the rain. She decided to trade her umbrella 'por' (in exchange for) a warm coffee. The coffee was made 'por' (by) her friend.
Word Web
Challenge
Write 3 sentences today using 'por' to explain why you did something.
Cultural Notes
In Brazil, 'por causa de' is extremely common in daily speech, often shortened to 'por causa'.
In Portugal, 'por' is used very precisely, and contractions are strictly observed.
Usage is similar to Brazil, with a focus on clear articulation of the 'r' sound.
Comes from the Latin 'per', meaning 'through'.
Conversation Starters
Por que você está aprendendo português?
O que você faria por um milhão de reais?
Quem foi o autor do seu livro favorito?
Por acaso você conhece alguém famoso?
Journal Prompts
Common Mistakes
Test Yourself
Fiz isso ___ você.
Which is correct?
Find and fix the mistake:
A casa foi pintada para eles.
Arrange the words in the correct order:
All words placed
Click words above to build the sentence
I did it for love.
Answer starts with: Fiz...
Ele foi elogiado ___ professor.
___ que você não veio?
Build a sentence.
Score: /8
Practice Exercises
8 exercisesFiz isso ___ você.
Which is correct?
Find and fix the mistake:
A casa foi pintada para eles.
por / você / estou / aqui
I did it for love.
Ele foi elogiado ___ professor.
___ que você não veio?
Build a sentence.
Score: /8
Practice Bank
10 exercisesEles viajaram ___ Europa durante um mês.
Estudei muito para esse motivo.
obrigado / convite / pelo / muito
I am waiting because of you.
Select the right one:
Match these pairs:
Vou ao ginásio três vezes ___ semana.
Fizemos isso para necessidade.
He is famous for his books.
Choose the best sentence:
Score: /10
FAQ (8)
No, use 'para' for destination. 'Por' is for cause or movement through.
In Portuguese, 'por' contracts with articles for better flow.
Yes, it indicates the agent performing the action.
Use 'porque' as a conjunction to mean 'because'.
It is neutral, but some constructions like passive voice are more formal.
Yes, 'por' can indicate duration, e.g., 'por duas horas'.
The rules are the same, but usage frequency of phrases like 'por causa de' varies.
Think of it as the 'reason' preposition.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
por
Very few differences in usage.
par / pour
French separates agent and reason more strictly.
durch / für
German relies on grammar cases rather than prepositional choice.
no tame ni / ni yotte
Japanese is postpositional.
bi-sabab / li-ajl
Arabic is highly contextual.
yinwei / wei
No contractions in Chinese.
Learning Path
Prerequisites
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