C1 · Advanced

The futuro and condicional of probability

How to use futuro, futuro perfecto, condicional and condicional compuesto to express a guess or supposition, and how to use 'deber de'.

The futuro simple for present probability

The futuro simple is not only used for the future, but also to express a guess about the present. You translate it with 'probably', 'must be' or 'I guess'.

The form is identical to the regular future tense: infinitive + ending (-é, -ás, -á, -emos, -éis, -án).

This use is very common in spontaneous speech, for example when answering a question you're not sure about.

Examples

¿Dónde está Pedro? Estará en la oficina.Where's Pedro? He's probably at the office.

Tendrá unos cuarenta años.He's probably around forty.

¿Qué hora es? Serán las tres.What time is it? It's probably three.

No contesta el teléfono; estará ocupada.She's not answering the phone; she's probably busy.

The futuro perfecto for probability in the recent past

The futuro perfecto (haber in the future + past participle) expresses a guess about something that has already happened, usually recently or right before the moment of speaking. It answers the question 'what has probably happened?'.

	hablar	comer	vivir
yo	habré hablado	habré comido	habré vivido
tú	habrás hablado	habrás comido	habrás vivido
él/ella/usted	habrá hablado	habrá comido	habrá vivido
nosotros/as	habremos hablado	habremos comido	habremos vivido
vosotros/as	habréis hablado	habréis comido	habréis vivido
ellos/ellas/ustedes	habrán hablado	habrán comido	habrán vivido

Examples

No ha llegado Marta. Habrá perdido el tren.Marta hasn't arrived. She's probably missed the train.

Se habrán olvidado de la reunión.They've probably forgotten about the meeting.

¿Por qué no ha llamado? Habrá tenido un problema.Why hasn't he called? He's probably had a problem.

The condicional simple for probability in the past

The condicional simple does in the past what the futuro simple does in the present: it expresses a guess, but seen from another point in the past. It's often combined with a past tense in the rest of the sentence.

Examples

Tendría unos treinta años cuando se casó.She was probably around thirty when she got married.

Serían las diez de la noche cuando sonó el teléfono.It was probably ten at night when the phone rang.

No sé por qué no vino; estaría enfermo.I don't know why he didn't come; he was probably sick.

The condicional compuesto and 'deber de': further back in the past

The condicional compuesto (habría + past participle) expresses a guess about something that had already happened before another point in the past — a kind of speculative pluperfect.

There is also a completely different way to express probability: 'deber de' + infinitive. Note the difference with 'deber' without 'de', which expresses an obligation.

deber + infinitive = obligation ('Debes estudiar más.' = You must study more.)
deber de + infinitive = probability ('Debe de ser tarde.' = It's probably late.)

Structuur	Betekenis/Meaning	Voorbeeld/Example
deber + infinitivo	verplichting / obligation	Debes estudiar más.
deber de + infinitivo	waarschijnlijkheid / probability	Debe de ser tarde.

Examples

Cuando llegamos, ya se habrían marchado todos.When we arrived, they had probably already left.

Debía de tener mucha hambre porque comió dos platos.He must have been very hungry, because he ate two plates.

No debe de ser fácil vivir tan lejos de tu familia.It probably isn't easy to live so far from your family.

💡 Tips

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Don't translate the futuro/condicional of probability literally with a future tense in English — use 'probably', 'must be', 'I guess'.

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Follow the timeline: futuro simple = guessing about now, futuro perfecto = guessing about the recent past, condicional simple = guessing about the past, condicional compuesto = guessing about an even earlier past.

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'deber de' (with de) = probability, 'deber' (without de) = obligation. In spoken Spanish this distinction is often blurred, but in written C1 Spanish it's useful to use it correctly.

🎯 Practise this topic with 10 interactive exercises (10)

Related grammar

Nuances of the subjunctive

How indicativo and subjuntivo change the meaning after aunque, cuando and quizás, and why negation often triggers the subjunctive.

Advanced verbal periphrases

Periphrases with venir, ir, andar, llevar sin, quedar por, dar por, tener + participle, llegar a, acabar por and echarse a.

← The many uses of 'se'Nuances of the subjunctive →

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