How to use ‘si’ clauses to express hypothetical situations in Spanish?

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In Spanish, hypothetical situations are expressed in a two-part sentence: one part uses the word si (if) to introduce a condition or hypothesis that may or may not be fulfilled, and the other states the consequence of this condition. Hypothetical situations can be possible, unlikely, or impossible, as shown below:

Possible: Si estudias, sacarás buenas notas.
If you study, you will get good grades.
Unlikely: Si estudiaras, sacarías buenas notas.
If you studied, you would get good grades.

Impossible: Si hubieras estudiado, habrías sacado buenas notas.
If you had studied, you would have gotten good grades.

Don’t be intimidated by this post’s topic, it’s not as hard as it sounds. Let me prove it to you.

Table of Contents

For a review of grammar terms used in this post, make sure to check out the Unpacking the grammar section at the end.

How to form hypothetical sentences in Spanish?

To form a hypothetical sentence, we combine the two parts, or clauses, discussed above. The main clause describes an action or an idea, whereas the conditional clause – headed by si (if) — introduces the condition. This condition may or may not be possible and the main clause indicates the result if the condition were fulfilled. For instance:

    Si clause
Main clause
Si llueve,
If it rains,
nos quedaremos en casa.
we will stay home.

Furthermore, the tense used in the si clause will determine the tense used in the main clause, so we have to pay attention to the combination of tenses. In this case we used the present indicative (llueve) and the simple future (quedaremos), but there are other possibilities.

Notice that just like English, the order of the clauses is irrelevant, but when the si clause goes first, don’t forget to write a comma right before the main clause:

Si salgo, te llamaré por teléfono. = Te llamaré por teléfono si salgo.
If I go out, I will call you. = I will call you if I go out.

⤷TIP Don’t confuse si (if), with no accent mark, with (yes).

Let’s take a closer look at each case!

Possible hypothetical sentences

In possible hypothetical sentences, the condition or hypothesis can lead to a real result or outcome. In the example above, if I end up going out, it is very likely I will make the call — hence it is a possible hypothesis.

Within the realm of possibility, we have different types that give us different meanings depending on the tense we use. Let’s start with the present:

Si clauseMain clause
Si + present indicative
  • Present indicative
  • Imperative
  • Future indicative

⤷TIP The future can also be expressed in the present tense or with ir a + infinitive:

Si (mañana) nieva no salgo / voy a salir de casa.
If it snows (tomorrow), I will not go out.

The future tense never goes after si in this type of hypothetical sentence. If you see a verb in the future tense after si, then it’s a different structure altogether and in this case si means “whether”:

No sé si saldré o no. I don’t know whether I’ll go out or not.

It’s possible to use a verb in the past tense in the si-clause when the speaker expresses uncertainty or doubt. In this case, you can use any tense in the past (preterite, imperfect, present perfect) paired with a verb in the present or the future in the main clause or in the imperative to give an order or request.
Si clauseMain clause
Si + preterite, imperfect,
or present perfect
  • Present, future, or

Si ya hablaste / has hablado con él, no insistiré en el asunto.
If you already spoke with him, I will not insist on the matter.

Si estaban tan preocupados, es mejor decirles la verdad.
If they were so worried, it’s better to tell them the truth.

Si ya terminaste de jugar, guarda tus juguetes.
If you’re done playing, put away your toys.

Notice how the condition expressed by the si clause is possible; all the previous examples talk about the possibility and a consequence that is possible in a variety of tenses.

Unlikely hypothetical sentences

In this type of hypothetical sentence, the condition or hypothesis makes the consequence unlikely to happen. These sentences express a situation that is contrary to the present truth, so there is still a slight chance that the condition will be fulfilled — even if unlikely.

In this case, similar to English, Spanish uses the present conditional tense to express the result of the condition. However, unlike English, which uses the simple past to express the condition, Spanish uses the imperfect subjunctive.

This type of sentence works like this:

Si clauseMain clause
Si + imperfect subjunctivePresent conditional

Si salieras de casa ahora, llegarías a tiempo a la estación del metro.

If you left home now, you would get to the metro station on time.

Si los clientes fueran más amables, no tendrían tantos problemas.

If the clients were nicer, they wouldn’t have so many problems.

Notice that this type of condition can theoretically be achieved because it refers to present facts — that is, you can leave your house now and make it to the metro station, or the clients can change their attitude to avoid problems. However, there is another type of hypothetical sentence that uses this same structure, but with conditions that are even more remote or unfulfillable. For example:

Si ganáramos la lotería, compraríamos una casa enorme.
If we won the lottery, we would buy a huge house.

Si fuera más alto, jugaría baloncesto.
If I were taller, I would play basketball.

In the first case, the likelihood of winning the lottery is remote, especially if we don’t play the lottery. Nevertheless, it is still possible that we buy a ticket and we win it — as unlikely as that may seem — and if we did, we would buy a huge house.

In the second example, it’s not likely that I will grow taller (as an adult), therefore the possibility of playing basketball because of this condition is quite unlikely.

This type of hypothetical sentence can be used for giving advice using the expression “si yo fuera tú” (If I were you), as in:

Si yo fuera tú no compraría un reloj tan caro.
If I were you I would not buy such an expensive watch.

⤷TIP When giving advice, the si-clause is often omitted, as it can be understood from context. For example,

Personalmente, no compraría un reloj tan caro.
Personally, I wouldn’t buy such an expensive watch.

In colloquial Spanish, you can replace “si yo fuera tú” with “yo que tú…” (me instead of you).

Yo que tú, no saldría a estas horas.
If I were you, I wouldn’t go out at this time.

Impossible hypothetical sentence

Impossible hypothetical sentences use the Spanish pluperfect subjunctive (aka past perfect subjunctive) to express conditions that are also contrary to the truth, but in this case a past truth. Therefore it is impossible to change the outcome.

There are two types of sentences:

Si clauseMain clause
Si + pluperfect subjunctive
  • Perfect conditional
  • Present conditional
  • Si + pluperfect subjunctive + perfect conditional

    They express a situation contrary to a past truth that cannot be changed and its result had consequences in the past.

    Si no hubiera salido, no habría perdido mi teléfono.

    If I hadn’t gone out, I wouldn’t have lost my phone.

    Si me hubieras escuchado, no habrías cometido tantos errores.

    If you had listened to me, you wouldn’t have made so many mistakes.


Colloquially, it is not uncommon to use the pluperfect subjunctive in both clauses:

Si no hubiera salido no hubiera perdido mi teléfono. = Si no hubiera salido, no habría perdido mi teléfono.
If I hadn’t gone out, I wouldn’t have lost my phone.

  • Si + pluperfect subjunctive + present conditional

    They express a situation contrary to a past truth, but in this case it affects the present.

    Si no hubiera salido, todavía tendría mi teléfono.

    If I hadn’t gone out, I would still have my phone.

    Si hubieras llegado temprano al aeropuerto, ahora estarías en el avión.

    If you had arrived early to the airport, you would now be on the plane.


Both unlikely and impossible sentences have something in common: they all use the imperfect or the pluperfect subjunctive, but never the present subjunctive!

To sum up

Let’s review the main points:
  • Hypothetical sentences in Spanish are always composed of two clauses: the main clause and a clause introduced by si that expresses a condition.
  • Depending on the type of condition expressed by the si clause, these sentences can either be possible, unlikely, or impossible.
    • Possible hypothetical sentences express a possible outcome if the condition is fulfilled.
    • Unlikely hypothetical sentences express conditions that make the situation unlikely to happen given the present facts.
    • Impossible hypothetical sentences describe conditions that cannot be fulfilled anymore since they refer to past events that have already happened.
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Are you interested in learning more about Spanish Grammar? Check out our Spanish Grammar Homepage.
Unpacking the grammar

Clause: a clause is a group of words that make up a sentence. It contains a subject and a predicate and it can be part of a compound, or complex, sentence. 

    • If you come early, we can go to the theater.

      This sentence has TWO CLAUSES
    1. If you come early, (dependent clause)
    2. we can go to the theater (main clause).

refers to the time of an event or state: present, past, or future.

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'Si' clauses activity


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