Se ("if") is the workhorse of conditional sentences, but it's blunt — it only says "if." Portuguese has a small family of more precise conditional conjunctions that say "provided that," "unless," "in case," and "as long as." Crucially, every one of them triggers the subjunctive, and each carries a sharper meaning than plain se. Learning them lets you say exactly what kind of condition you mean. This page assumes you can form the present and imperfect subjunctive; here we focus on which conjunction to choose and why they all demand the subjunctive.
Why they all take the subjunctive
There is a single reason behind the whole list: these conjunctions introduce a condition that is not yet a fact — it's a hypothesis, a requirement, or an exception. That non-factual status is exactly what the subjunctive marks. Whereas plain se can sometimes take the indicative (in real, open conditions like Se chove, eu fico em casa), these specialized conjunctions are inherently hypothetical, so they lock you into the subjunctive every time.
Caso — "in case / if" (the formal alternative to se)
Caso means "in case" or simply "if," and it's the most common upgrade from se. It takes the present subjunctive for future possibilities. It feels slightly more formal and precise than se, and it's everywhere in writing, instructions, and careful speech.
Caso chova, eu levo o guarda-chuva.
In case it rains, I'll take the umbrella.
Caso você precise de qualquer coisa, é só me ligar.
If you need anything, just call me.
Caso o voo atrase, a companhia avisa por mensagem.
In case the flight is delayed, the airline notifies you by text.
Note that caso chova uses the present subjunctive chova, where se would have taken the future subjunctive (se chover). This is a key contrast: se + future subjunctive but caso + present subjunctive.
| With se | With caso |
|---|---|
| Se chover, eu levo o guarda-chuva. (future subj.) | Caso chova, eu levo o guarda-chuva. (present subj.) |
| Se você precisar, me ligue. (future subj.) | Caso você precise, me ligue. (present subj.) |
Desde que — "provided that / as long as"
Desde que sets a requirement: the result holds only on the condition that something is true. (Watch out — desde que also means "since" in a time sense; the conditional meaning is the one that takes the subjunctive.)
Eu te empresto o carro, desde que você devolva com o tanque cheio.
I'll lend you the car, provided you return it with a full tank.
A gente vai à praia no domingo, desde que faça sol.
We'll go to the beach on Sunday, as long as it's sunny.
Você pode usar meu notebook, desde que não mexa nos meus arquivos.
You can use my laptop, as long as you don't touch my files.
Contanto que — "as long as / so long as"
Contanto que is a near-synonym of desde que in its conditional sense, and slightly more emphatic about the requirement. It's common in both speech and writing.
Eu vou na festa, contanto que você vá comigo.
I'll go to the party, as long as you come with me.
O médico disse que ele pode treinar, contanto que não force o joelho.
The doctor said he can train, as long as he doesn't strain his knee.
A menos que / a não ser que — "unless"
These mean "unless," and they're logically the mirror image: they introduce the exception that would block the result. Both take the subjunctive; a não ser que is a touch more colloquial.
A gente vai fazer o churrasco amanhã, a menos que chova.
We're going to have the barbecue tomorrow, unless it rains.
Eu não vou aceitar, a não ser que eles aumentem o salário.
I'm not going to accept, unless they raise the salary.
Ninguém entra aqui, a menos que tenha autorização.
Nobody comes in here unless they have authorization.
Sem que — "without (someone doing something)"
Sem que expresses a condition of absence — something happens without something else occurring. It always takes the subjunctive and is the conditional/manner cousin of the simple preposition sem + infinitive.
Ele saiu sem que ninguém percebesse.
He left without anyone noticing.
Não dá pra resolver isso sem que todos colaborem.
There's no solving this without everyone cooperating.
Use sem que when the two clauses have different subjects (he left / nobody noticed). When the subject is the same, prefer sem + infinitive: Ele saiu sem se despedir ("He left without saying goodbye").
The gerund as a compact conditional
Brazilian Portuguese can compress a whole conditional into a single gerund clause, with no conjunction and no subjunctive at all. This is concise and very common in speech, advice, and advertising.
Estudando todo dia, você passa no vestibular.
If you study every day, you'll pass the college entrance exam. (lit. 'Studying every day...')
Comprando dois, você ganha o terceiro de graça.
If you buy two, you get the third free. (typical ad phrasing)
Tendo paciência, tudo se resolve.
If you're patient, everything works out.
The gerund conditional only works when the subject is recoverable from context (usually a generic "you"). It can't carry tense distinctions, so it stays in the realm of open, general conditions — you wouldn't use it for counterfactuals.
Quick reference
| Conjunction | Meaning | Mood | Typical register |
|---|---|---|---|
| caso | in case / if | present subjunctive | (formal), writing, instructions |
| desde que | provided that | subjunctive | neutral |
| contanto que | as long as | subjunctive | neutral |
| a menos que | unless | subjunctive | neutral |
| a não ser que | unless | subjunctive | (informal) leaning |
| sem que | without (someone -ing) | subjunctive | neutral |
| gerúndio (-ndo) | if/by -ing | (no subjunctive) | (informal), advice, ads |
Common Mistakes
❌ Caso chover, eu levo o guarda-chuva.
Incorrect — 'caso' takes the present subjunctive 'chova', not the future subjunctive 'chover'.
✅ Caso chova, eu levo o guarda-chuva.
In case it rains, I'll take the umbrella.
This is the number-one error: applying the se-style future subjunctive (chover, precisar) after caso. Caso takes the present subjunctive.
❌ Desde que você devolve o carro, eu te empresto.
Incorrect — conditional 'desde que' requires the subjunctive 'devolva', not the indicative 'devolve'.
✅ Desde que você devolva o carro, eu te empresto.
Provided you return the car, I'll lend it to you.
English "provided you return" uses a bare present, so learners copy the indicative. Portuguese needs the subjunctive here.
❌ A menos que você não estude, você vai reprovar.
Incorrect — double-negative meaning. 'Unless' already means 'if not', so adding 'não' reverses the sense.
✅ A menos que você estude, você vai reprovar.
Unless you study, you're going to fail. (i.e. if you don't study, you'll fail)
Because a menos que already contains the "if not" logic, adding não inside it flips the meaning — a classic transfer trap from translating "unless" word-by-word.
❌ Ele saiu sem que se despedir.
Incorrect — same-subject sentences use 'sem' + infinitive, not 'sem que' + subjunctive.
✅ Ele saiu sem se despedir.
He left without saying goodbye.
Use sem que + subjunctive only when subjects differ; for a shared subject, use sem + infinitive.
❌ Estudar todo dia, você passa no vestibular.
Incorrect — the compact conditional uses the gerund, not the infinitive.
✅ Estudando todo dia, você passa no vestibular.
If you study every day, you'll pass the entrance exam.
The conditional reading requires the -ndo gerund (estudando), not the infinitive.
Key Takeaways
- Caso, desde que, contanto que, a menos que, a não ser que, and sem que all force the subjunctive because each introduces a non-factual condition.
- Caso
- present subjunctive is the precise, slightly formal stand-in for se — and notably differs from se
- future subjunctive.
- present subjunctive is the precise, slightly formal stand-in for se — and notably differs from se
- A menos que means "if not," so never add não inside it.
- The gerund (estudando) packs an entire open conditional into one word — informal and very Brazilian.
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
- Subjunctive with Triggering ConjunctionsB1 — Conjunctions like para que, antes que, embora, and caso that always force the subjunctive in Brazilian Portuguese.
- Contrary-to-Fact Conditionals (Present)B1 — Present hypotheticals in Brazilian Portuguese — se + imperfect subjunctive + conditional (Se eu tivesse dinheiro, compraria), and the colloquial swap of conditional for imperfect indicative (comprava).
- Open Conditionals (Real If-Clauses)A2 — Real, possible if-clauses in Brazilian Portuguese — present indicative for habits and the obligatory future subjunctive (se chover) for specific future conditions.
- Imperfeito do Subjuntivo: UsageB1 — When to use the imperfect subjunctive in Brazilian Portuguese — hypothetical 'se' clauses, past-tense triggers, 'como se', and softened wishes.
- Conditional Conjunctions (Se, Caso)B1 — How se, caso, a menos que, contanto que and desde que introduce conditions — and why each one selects a specific mood depending on the type of condition.