When a Portuguese speaker says Que horas serão?, they are not asking what time it will be. They are asking what time it is, right now -- but with a veil of uncertainty. The simple future has a second life as a marker of conjecture about the present, and this use has almost nothing to do with future time. It is one of the most elegant and most overlooked features of Portuguese. Learning to recognize it will stop you from misreading sentences, and learning to use it will give your Portuguese a register that no amount of vou + infinitive can replace.
For the formation of the tense itself, see Simple Future.
What the future of probability actually expresses
A simple future verb such as serão, estará, terá, dará can refer to:
- An event in the future (the textbook meaning): O jantar será às oito ("Dinner will be at eight").
- A guess about the present: Serão umas oito ("It must be around eight").
The second meaning is what this page is about. It lets the speaker hedge a present-time claim as though it were a forecast. English does the same thing with will (that'll be the postman) and with must (he must be tired). Portuguese formalizes this into a clear grammatical pattern.
Que horas serão?
What time might it be? / I wonder what time it is.
Ele estará doente, não aparece há uma semana.
He must be ill -- he hasn't shown up in a week.
O senhor terá uns setenta anos.
That gentleman must be around seventy.
Onde estará o meu telemóvel?
Where on earth is my phone?
Será verdade?
I wonder if it's true. / Could it be true?
Notice that every one of these sentences is about right now, not about some future moment. The future-tense form is what hedges the claim.
How conjecture reads in English
The closest English translations are must be, could be, probably is, I wonder, -ish, or that'll be.... Pick whichever suits the tone.
| Portuguese | English |
|---|---|
| Serão umas dez. | It must be about ten. |
| Ele terá uns trinta anos. | He's probably around thirty. |
| Que dirá ela? | What might she be saying? |
| Onde estará o gato? | Where on earth is the cat? |
| Será que ele já chegou? | I wonder if he's arrived. |
English will for probability survives mainly in British English (that'll be Mum at the door), but the must + verb pattern is universal. Both fit the Portuguese future of probability well.
Typical contexts
The construction is not equally frequent everywhere. Some situations pull for it especially strongly.
Time, age, measurements, and amounts
When the speaker is estimating a number or quantity in the present, the future of probability is the idiomatic choice.
Que horas serão? — Serão umas três da tarde.
What time is it, do you think? — It must be around three in the afternoon.
Ela terá uns vinte e cinco anos, no máximo.
She's probably about twenty-five, at most.
Aquele prédio terá uns dez andares.
That building must have about ten floors.
Quanto custará este casaco?
How much does this coat cost, would you say?
Speculation about someone's state or location
When the speaker guesses at someone's current condition, feeling, or whereabouts.
O chefe estará à espera há meia hora, vamos mas é andando.
The boss must have been waiting for half an hour, let's get going.
O que terá ela na cabeça para fazer uma coisa destas?
What must be going through her head to do something like this?
Por onde andará o João a esta hora?
Where could João be at this time?
Rhetorical questions -- especially with será que
The expression será que...? opens a rhetorical or speculative question. It maps onto English I wonder if..., could it be that...?
Será que ele se esqueceu?
I wonder if he's forgotten.
Será que vale a pena tentar outra vez?
Could it be worth trying again?
Será que é hoje ou amanhã?
Is it today or tomorrow, I wonder?
Será que is so common in European Portuguese that many speakers use it as a softener for almost any question. It is not obligatory -- you can ask Ele esqueceu-se? for the same information -- but será que adds a layer of doubt or politeness.
Register: where this construction lives
The future of probability is neutral to literary. It appears in writing, in careful speech, in newspaper prose, in journalistic commentary, and in the kind of reflective speech you would find at a dinner table among educated adults. In casual conversation with friends, speakers more often use alternatives (see the next section), though será que and que horas serão are fully colloquial.
(news commentary) O relatório terá consequências políticas significativas.
The report must have significant political consequences.
(literary) Nada saberão eles das dificuldades por que passámos.
They will know nothing of the hardships we went through. (can be read as conjecture about their present ignorance)
(everyday speculation) O carro estará avariado, faz um barulho estranho.
The car must be broken -- it's making a strange noise.
Alternatives in everyday speech
Casual speakers very often reach for alternatives instead of the future of probability. Know these too, because you will hear them constantly.
Dever + infinitive
The verb dever in the present indicative means "must, ought to" and is the standard everyday way to express probability. See Dever for Probability for a full treatment.
Devem ser umas dez.
It must be about ten.
Ele deve estar doente.
He must be ill.
A Ana deve ter uns trinta anos.
Ana must be around thirty.
Acho que... / Se calhar / Provavelmente
Softening expressions let the speaker hedge without any special verb form.
Acho que é por volta das dez.
I think it's around ten.
Se calhar ele está doente.
Maybe he's ill.
Provavelmente a Ana tem uns trinta.
Ana is probably about thirty.
The future of probability (literary / written)
Serão umas dez.
It must be around ten.
Estará doente.
He must be ill.
A Ana terá uns trinta anos.
Ana must be around thirty.
Compare the three rows side by side. All three are correct. The first two are what a Lisboeta says across a kitchen table; the third is what the same speaker writes in an email at work or what a novelist writes in prose.
| Everyday speech | Neutral writing | Literary / reflective |
|---|---|---|
| Devem ser umas dez. | Provavelmente são umas dez. | Serão umas dez. |
| Ele deve estar em casa. | Acho que ele está em casa. | Estará em casa. |
| A Ana deve ter uns trinta. | A Ana tem uns trinta, se calhar. | A Ana terá uns trinta. |
The mirror image: conditional of probability about the past
The future of probability has a twin. When the speaker wants to hedge a claim about the past, Portuguese uses the conditional, not the future. The structural parallel is exact.
Seria meia-noite quando cheguei.
It must have been around midnight when I arrived.
Ela teria uns vinte anos nessa altura.
She must have been about twenty at the time.
Quem bateria à porta àquela hora?
Who would have been knocking at the door at that hour?
Future tense hedges the present; conditional hedges the past. See Conditional Tense Overview for the full picture.
Why Portuguese uses the future this way
The connection between future time and uncertainty is not arbitrary. A future event is, by definition, not yet verified; saying it will be so is always a kind of prediction. Portuguese (like Spanish, French, and Italian) has extended that predictive quality to the present: a claim about right now, framed as if the speaker were forecasting it, carries the same hedged feel. You are saying "based on what I can see, I predict that it is so."
English preserved the same logic in the use of will in phrases like that'll be her, where the speaker is guessing who just rang the doorbell. Portuguese made the pattern productive across the whole tense, so almost any present-time guess can be expressed this way.
Common Mistakes
❌ Será de manhã, vou ao café. (intending: 'I'm going to the cafe in the morning')
Confuses the future of probability with an actual future event -- reads as 'I wonder if it's morning' + an unconnected sentence.
✅ De manhã vou ao café. / Amanhã de manhã vou ao café.
I'm going to the cafe in the morning. / Tomorrow morning I'll go to the cafe.
The future of probability is about speculation, not about scheduling. Do not use it when you mean a genuine future event in daily conversation -- especially in a casual register. Use ir + infinitive or the present-as-future instead.
❌ Eu saberá a resposta.
Wrong person agreement -- terá, saberá, estará are third-person singular forms.
✅ Eu saberei a resposta.
I will know the answer. (actual future)
✅ Ele saberá a resposta.
He must know the answer. (conjecture)
Like any future-tense verb, the future of probability takes person-specific endings. The frequently cited examples (serão, estará, terá) are third-person forms because speakers usually speculate about someone or something else, not about themselves.
❌ Que horas vão ser?
Incorrect -- Portuguese does not use ir + infinitive for conjecture about the present.
✅ Que horas serão?
What time might it be?
✅ Que horas são?
What time is it?
Ir + infinitive expresses intention or prediction of a future event. It is not a substitute for the simple future in the conjectural use. For speculation about the present, you need either the simple future (serão) or one of the alternatives (devem ser).
❌ Ele estará doente amanhã. (intending: 'He must be sick right now')
Incorrect -- the adverb amanhã forces a future-time reading.
✅ Ele estará doente (agora mesmo / neste momento).
He must be sick right now.
Adding a future time adverb (amanhã, na próxima semana) overrides the conjectural reading and forces a literal future interpretation. Keep the sentence anchored in the present if you mean speculation.
❌ Será que... é verdade? (as an introduction to a story, telling what happens next)
Inappropriate register -- será que introduces speculation, not narration.
✅ Será que é verdade? (after hearing a rumour)
I wonder if it's true.
Será que... is a speculative opener, not a narrative one. Do not use it when you are reporting events; use it when you are expressing genuine doubt or curiosity.
Key takeaways
- The simple future can express conjecture about the present, not only future events.
- Typical contexts: time, age, measurements, location, inner states, rhetorical questions with será que.
- Register: neutral to literary / formal. In casual speech, many speakers prefer dever
- infinitive or softening adverbs.
- Mirror image: the conditional expresses the same kind of conjecture but about the past (seria meia-noite).
- English parallel: must be, could be, that'll be, I wonder.
- Do not confuse the conjectural use with genuine future time -- adverbs like amanhã, logo, na sexta force a future-time reading.
- Será que...? is a high-frequency way to open a speculative question in both speech and writing.
Related Topics
- Simple Future (Futuro do Presente)A2 — Formation and uses of the synthetic future tense in European Portuguese
- Future Tense OverviewA2 — Three ways to express the future in European Portuguese, from casual speech to formal writing
- Conditional Tense OverviewB1 — Formation and uses of the conditional (futuro do pretérito)
- Ir + Infinitive (Informal Future)A1 — The most common way to express future in spoken Portuguese