Porque vs. Por Isso: Explain Causes and Results in Portuguese
Connect two ideas clearly: explain why something happened or state what happened as a result.
Real Life Portuguese · 7 min read · Updated October 14, 2026
The short answer
Porque usually means “because” when it introduces the reason for an action or situation. Put the result or main statement first, then explain why it happened: fiquei em casa porque estava chovendo (I stayed home because it was raining).
Use porque to explain the reason
If you are asking “why?”, write por que as two words in a direct question. This article focuses on porque as a cause connector and por isso as a result connector, so keep those jobs separate as you practice.
Não fui à praia porque estava cansado.
I didn’t go to the beach because I was tired.
Ela chegou cedo porque queria conversar com a professora.
She arrived early because she wanted to talk with the teacher.
Estamos estudando porque a prova é amanhã.
We’re studying because the test is tomorrow.
Use por isso to introduce a result
Por isso means “that is why,” “therefore,” or “because of that.” It points back to a reason that has already been stated, then introduces its consequence: estava chovendo; por isso, fiquei em casa (it was raining; that’s why I stayed home).
The phrase can start a sentence or connect ideas after a semicolon or pause. In relaxed conversation, you may hear e por isso… (and that’s why…). Use punctuation to make the relationship clear in writing.
O trânsito estava parado; por isso, me atrasei.
Traffic was at a standstill; that’s why I was late.
A loja fecha cedo. Por isso, vamos sair agora.
The store closes early. That’s why we’re leaving now.
Ele treinou bastante e por isso melhorou.
He practiced a lot, and that’s why he improved.
Compare which idea comes first
Because points from a statement toward its cause; por isso points from a cause toward its result. Compare: Não saí porque estava cansado (I didn’t go out because I was tired) and Estava cansado, por isso não saí (I was tired, so I didn’t go out). The facts are similar, but the sentence order changes.
When translating from English, do not rely only on the word “because.” Ask whether your Portuguese clause gives the reason or names what followed from it.
Perdi o ônibus porque saí tarde.
I missed the bus because I left late.
Saí tarde; por isso, perdi o ônibus.
I left late; that’s why I missed the bus.
Ela não respondeu porque estava em uma reunião.
She didn’t reply because she was in a meeting.
Give a reason and keep the conversation moving
A concise reason helps the listener follow your plans, choices, or delay. Use porque for the reason after an action, or state the reason first and use por isso to introduce the result. You can add então for “so/then” when you are moving to the next step.
For more connectors, continue with Real Life Portuguese guides to então and everyday explanations. I Speak Portuguese teachers can help you tell a short story with a clear cause and result. Keep one main idea in each clause when you are building confidence.
Vou trabalhar de casa porque o técnico vem hoje.
I’m going to work from home because the technician is coming today.
O técnico vem hoje; por isso, vou trabalhar de casa.
The technician is coming today; that’s why I’m working from home.
Por isso, prefiro confirmar o endereço antes de sair.
That’s why I prefer to confirm the address before leaving.
Put it into practice
Use porque to introduce a reason and por isso to point from a reason to its result. Check which idea comes first before choosing the connector.
Quick practice
Which Portuguese example matches “I missed the bus because I left late”?
Choose an answer to check yourself.
Keep practicing with the Real Life Portuguese app
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