portanto/por isso
Therefore
Use por isso for everyday 'so/therefore' and portanto for more formal or logical conclusions. Both link a cause to an effect.
How It Works
In Portuguese, connecting ideas logically is essential for fluency. These two connectors are the most common ways to express a result:
1. Por isso (Literally: 'For that'):
This is the most natural way to say 'so' or 'that's why' in daily life. It almost always appears at the beginning of the clause that describes the result.
Example: Estou cansado, por isso vou dormir. (I am tired, so I'm going to sleep.)
2. Portanto (Therefore):
This is more formal and carries a weight of logical deduction. It is common in essays, business meetings, and European Portuguese speech. Unlike por isso, it is mobile. You can place it after the verb or subject to sound more sophisticated, provided you isolate it with commas.
Example: O plano é caro; não podemos, portanto, aceitá-lo. (The plan is expensive; we cannot, therefore, accept it.)
Punctuation Note: Both usually require a comma before them when connecting two independent thoughts. If portanto is moved to the middle of a sentence, it must be surrounded by commas on both sides.
Examples (5)
- Estava a chover muito, por isso decidimos ficar em casa.
It was raining a lot, so we decided to stay home.
Word by Word: Was to rain much, for that we decided to stay in house.
A classic use of 'por isso' in an everyday situation to link a cause (rain) to a result (staying home).
- Temos todos os ingredientes, portanto podemos começar a cozinhar.
We have all the ingredients, therefore we can start cooking.
Word by Word: We have all the ingredients, therefore we can start to cook.
Using 'portanto' at the start of the clause to show a logical conclusion.
- O réu é primário; não deve, portanto, ser condenado à pena máxima.
The defendant is a first-time offender; he should not, therefore, be sentenced to the maximum penalty.
Word by Word: The defendant is primary; not must, therefore, be condemned to the penalty maximum.
This demonstrates the 'intercalated' position of 'portanto' after the verb, which is common in formal legal or academic writing.
- Ele não estudou nada, por isso reprovou no exame.
He didn't study at all, so he failed the exam.
Word by Word: He not studied nothing, for that failed in the exam.
A direct cause-and-effect relationship using the standard conversational connector.
- A empresa teve prejuízo e, portanto, haverá cortes no orçamento.
The company had a loss and, therefore, there will be budget cuts.
Word by Word: The company had loss and, therefore, there will be cuts in the budget.
A formal business context where 'portanto' is the most appropriate choice.
Common Mistakes
Confusing 'portanto' with 'por tanto'.
Obrigado portanto carinho.Obrigado por tanto carinho.'Portanto' (one word) means 'therefore'. 'Por tanto' (two words) means 'for so much'. They sound similar but have completely different functions.
Using 'portanto' in very casual slang-filled conversations.
Cara, tô com fome, portanto vou comer um lanche.Cara, tô com fome, por isso vou comer um lanche.While grammatically correct, 'portanto' sounds overly stiff and 'bookish' when used with slang like 'cara' or 'tô'. Use 'por isso' or 'então' for casual speech.
Forgetting commas when 'portanto' is moved to the middle of the sentence.
Ele é portanto o culpado.Ele é, portanto, o culpado.When 'portanto' is placed after the verb or subject (intercalated), it must be isolated by commas to mark the interruption in the sentence flow.
How It Connects
Learn This First
To use 'portanto' and 'por isso' effectively, you need to understand how to link two ideas where one is the result of the other. This requires familiarity with basic sentence structure, the causal preposition 'por', and how the neuter pronoun 'isso' refers back to entire ideas or statements.
- e/ou/mas/porqueBasic Conjunctions
Understanding basic conjunctions like 'porque' (because) is essential for grasping how 'portanto' and 'por isso' function as their logical counterparts to express results.
Foundations - porPor Uses
The connector 'por isso' is a contraction of the preposition 'por' and the demonstrative 'isso', so understanding the causal use of 'por' is fundamental.
Level 2 - issoDiscourse Deixis with Isso
The 'isso' in 'por isso' functions as a discourse marker that refers back to a previously stated cause or situation.
Level 3
Related Patterns
- entãoSo/Then
Another common way to say 'so' or 'then' in informal speech, often used interchangeably with 'por isso'.
Level 3 - mas/porémBut (Coordinating Contrast)
While 'portanto' shows a result, these connectors show a contrast or opposition.
Level 3 - por conseguinte/consequentementeConsequently
Even more formal synonyms for 'portanto' used in high-level academic or legal writing.
Level 5
Learn Next
Patterns that build on this one.
Words in This Pattern
Practice portanto/por isso in Bubblegum
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