English has a tidy division of labor: but is the everyday conjunction, and however is the formal, movable adverb. Portuguese works almost exactly the same way — mas behaves like but, and porém (with its cousins contudo, todavia, no entanto) behaves like however. The two are not interchangeable, and the difference is half about register and half about where the word is allowed to sit in the sentence. Get the syntax wrong and the sentence reads as ungrammatical to a native ear.
The core distinction
- mas is a coordinating conjunction. It is fixed: it sits at the boundary between the two clauses and cannot move. It is the neutral, all-purpose word for "but" — spoken or written.
- porém (and contudo, todavia, no entanto) is a conjunctive adverb meaning "however". It is mobile — it can sit at the start, the middle, or the end of the second clause — and it is set off by commas. It belongs to more formal or written registers.
É caro, mas vale a pena.
It's expensive, but it's worth it.
É caro; vale a pena, porém.
It's expensive; it is, however, worth it.
Same meaning, but notice that porém slid to the end of the clause. Mas could never do that — it is welded to the position between the clauses.
Mas — the everyday "but"
Mas is what you reach for in conversation and most ordinary writing. It joins two clauses and always sits right at the seam between them. It cannot move into the middle of the second clause, and you do not normally surround it with commas on both sides.
Eu queria ir, mas estou sem dinheiro.
I wanted to go, but I'm broke.
Ela estudou muito, mas não passou na prova.
She studied a lot, but she didn't pass the test.
Não é bonito, mas é confortável.
It's not pretty, but it's comfortable.
In speech, mas also has a discourse use at the start of a turn — roughly English "but" / "well, but" — to push back or react:
Mas que história é essa?
But what's this all about?
Porém — the formal, mobile "however"
Porém is the workhorse of formal and written contrast. Three things distinguish it from mas:
- Register. It is more formal. You see it in essays, journalism, business emails, and careful speech, rarely in casual chat.
- Mobility. It can open the clause, sit after the first element, or close the clause.
- Punctuation. It is set off by commas (or follows a semicolon/period).
O projeto foi aprovado; porém, o orçamento ainda não foi liberado.
The project was approved; however, the budget still hasn't been released.
A proposta é interessante. Os custos, porém, são altíssimos.
The proposal is interesting. The costs, however, are extremely high.
Tentamos resolver de forma amigável; não conseguimos, porém.
We tried to settle it amicably; we couldn't, however.
Notice the middle example: porém is wedged between the subject (os custos) and the verb (são). That mid-clause placement is impossible for mas — this is the single clearest test of which word you are dealing with.
Contudo, todavia, no entanto — the porém family
These three are stylistic variants of porém. They share its syntax (mobile, comma-set, formal) and differ only in flavor:
- no entanto — the most common and most neutral of the formal set; very frequent in journalism. (formal)
- contudo — slightly more emphatic, common in argumentative writing. (formal)
- todavia — the most literary and old-fashioned of the group; you will meet it in essays and literature more than in everyday prose. (literary / formal)
Os números melhoraram. No entanto, a equipe não está satisfeita.
The figures improved. However, the team isn't satisfied.
Ele prometeu mudar; contudo, tudo continuou igual.
He promised to change; nevertheless, everything stayed the same.
A vitória parecia certa; todavia, o destino reservava outra coisa.
Victory seemed certain; yet fate had something else in store.
A useful intensifier you will also hear with mas is mas... porém or, very commonly in speech, the redundant mas porém — note that this stacked form is considered nonstandard and is best avoided in writing.
A note on "but rather" — mas / mas sim
When the contrast is corrective ("not X but rather Y"), Portuguese uses mas or, more emphatically, mas sim:
Não foi por dinheiro, mas sim por princípio.
It wasn't for money, but rather on principle.
This corrective sense belongs to mas, not porém — another reason the two are not freely swappable.
Decision summary
| Question | Answer points to… |
|---|---|
| Casual speech or neutral writing? | mas |
| Formal essay, news, or business prose? | porém / no entanto / contudo |
| Does the word move into the middle/end of the clause? | porém family (never mas) |
| Is it stuck at the clause boundary? | mas |
| Corrective "not X but rather Y"? | mas / mas sim |
| Literary, elevated tone? | todavia |
Common Mistakes
❌ É caro, mas, vale a pena, mas.
Incorrect — mas cannot move to the end of the clause.
✅ É caro; vale a pena, porém.
It's expensive; it is, however, worth it.
❌ Os custos mas são altíssimos.
Incorrect — mas cannot sit between subject and verb.
✅ Os custos, porém, são altíssimos.
The costs, however, are extremely high.
❌ Oi, queria ir mas porém estou cansado.
Incorrect (nonstandard) — stacking mas + porém is redundant.
✅ Oi, queria ir, mas estou cansado.
Hi, I wanted to go, but I'm tired.
❌ A proposta é boa. Mas, os custos são altos.
Awkward — starting a new sentence with bare 'Mas,' in formal writing reads as too colloquial.
✅ A proposta é boa. Os custos, porém, são altos.
The proposal is good. The costs, however, are high.
Key Takeaways
- mas = coordinating "but"; fixed at the clause boundary; neutral register; works everywhere in speech.
- porém / contudo / todavia / no entanto = adverbial "however"; mobile and comma-set; formal/written register.
- The decisive test: only the porém family can sit mid-clause (between subject and verb) or at the clause's end.
- For corrective contrast ("not X but rather Y"), use mas (sim) — not porém.
Now practice Portuguese
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning Portuguese→Related Topics
- Choosing Between Confusable Pairs: OverviewA2 — A map of the word choices Brazilian Portuguese forces on English speakers — where English uses one word (be, for, know, bring, say) and Portuguese splits it into two or three.
- Contrast Markers (Mas, Porém, Contudo)A2 — How Brazilian Portuguese signals contrast on a register ladder, from the everyday 'mas' to the formal 'porém', 'contudo' and 'todavia'.
- Adversative Conjunctions (Mas, Porém, Contudo)A2 — The full set of contrast conjunctions in Brazilian Portuguese — mas, porém, contudo, todavia, no entanto, entretanto — graded by register, plus the mobile-adverbial behavior of porém and the special word senão.
- Formal Connectors for WritingB2 — The high-formal stratum of Brazilian Portuguese connectors — outrossim, ademais, não obstante, doravante, por conseguinte — that lives in legal and academic prose, when they fit, and when they just sound pompous.
- Coordinating ConjunctionsA1 — The five classes of coordinating conjunction in Brazilian Portuguese — additive, adversative, alternative, conclusive, explicative — with comma rules and the key contrast with Spanish.