Expressing Probability in Spanish

Spanish has a rich set of tools for expressing probability, speculation, and uncertainty. In this lesson, we explore how to use the future tense for present probability, the conditional tense for past probability, and a variety of adverbs and expressions to indicate how certain or uncertain you are.

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The Future of Probability (Present)

As introduced in Lesson 4, the future tense can express speculation about what is happening right now:

How It Works

Instead of stating a fact, you express a reasonable guess about the present:

Future Tense (Probability)	English Equivalent
Serán las tres.	It's probably three o'clock. / It must be three.
¿Qué hora será?	I wonder what time it is.
¿Dónde estará Juan?	I wonder where Juan is. / Where could Juan be?
Estará en el trabajo.	He's probably at work. / He must be at work.
Tendrá unos cuarenta años.	He's probably about forty. / He must be about forty.
¿Quién será esa mujer?	I wonder who that woman is.
Costará unos cien euros.	It probably costs about a hundred euros.
No contestará porque estará ocupado.	He's not answering because he must be busy.

More Examples in Context

• Hará mucho frío fuera — no hay nadie en la calle. — It must be very cold outside — there's nobody in the street.
• Tendrán hambre después de caminar tanto. — They must be hungry after walking so much.
• ¿Por qué no viene? Sabrá que estamos aquí? — Why isn't she coming? I wonder if she knows we're here.
• Habrá unas doscientas personas en la sala. — There are probably about two hundred people in the room.
• No sé cuánto cuesta, pero será caro. — I don't know how much it costs, but it's probably expensive.

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The Conditional of Probability (Past)

The conditional tense can express speculation about what was happening in the past — typically referring to a specific past moment:

How It Works

Conditional (Past Probability)	English Equivalent
Serían las tres cuando llegó.	It was probably three when he arrived.
¿Dónde estaría Juan ayer?	I wonder where Juan was yesterday.
Estaría en el trabajo.	He was probably at work.
Tendría unos cuarenta años cuando se casó.	He was probably about forty when he got married.
Costaría unos cien euros.	It probably cost about a hundred euros.
Habría unas cien personas en la fiesta.	There were probably about a hundred people at the party.

Comparing Present and Past Probability

Present Probability (Future Tense)	Past Probability (Conditional Tense)
Serán las tres.	Serían las tres.
(It's probably three.)	(It was probably three.)
Estará en casa.	Estaría en casa.
(He's probably at home.)	(He was probably at home.)
Tendrá unos veinte años.	Tendría unos veinte años.
(She's probably about twenty.)	(She was probably about twenty.)
Costará mucho.	Costaría mucho.
(It probably costs a lot.)	(It probably cost a lot.)

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Adverbs and Expressions of Probability

Beyond using verb tenses, Spanish has many adverbs and expressions to indicate degrees of probability:

High Probability

Expression	Meaning	Example
seguramente	surely, most likely	Seguramente vendrá. (He'll surely come.)
seguro que	surely, I bet	Seguro que apruebas. (I bet you'll pass.)
sin duda	without a doubt	Sin duda ganarán. (They'll win without a doubt.)
con toda seguridad	with complete certainty	Con toda seguridad aceptará.
estoy seguro/a de que	I'm sure that	Estoy segura de que lo sabe.
es seguro que	it's certain that	Es seguro que lloverá.
desde luego	of course	Desde luego que sí.
por supuesto	of course	Por supuesto que vendrá.

Medium Probability