How To Use ‘Si,’ the Spanish Word for ‘If’

Verb choice depends on likelihood of event

Cancun beachfront
Si tengo dinero, me iré de viaje. (If I have money, I'll go on a trip.) Photo is of the beach at Cancún, Mexico.

Ricardo Diaz / Creative Commons.

Usually, "if" and its Spanish equivalent, si, are used to form what are known as conditional sentences.

Although the rules of Spanish grammar for conditional sentences can get complex, in the vast majority of cases the main thing you need to know is which verb tense to use after si.

Verb Tense in Spanish 'If' Sentences

The first thing is to remember that except in very rare cases, si is never followed by a verb in the present-tense subjunctive mood.

That said, there are basically two types of si clauses that become part of a sentence:

  1. Sentences in which the condition is likely or reasonably likely. This is known grammatically as an open condition. For example, in the clause si llueve ("if it rains"), rain is seen as a distinct possibility.
  2. Sentences in which the condition is contrary to fact or is unlikely. For example, the clause si lloviera can be translated as "if it were to rain." Note the difference in meaning from the example above; in this case, while rain is a possibility, it is seen as unlikely. An example of a contrary-to-fact condition is a clause such as si yo fuera rico, "if I were rich." Grammatically, contrary-to-fact and unlikely conditions are treated the same way.

The correct verb tense following si can be observed in the above examples. In open conditions, conditions where the possibility is reasonably likely, si is followed by the present indicative tense (the most common tense, probably the first one you learned as a Spanish student). If the condition is unlikely or false, a past subjunctive (usually the imperfect subjunctive) is used. This is the case even when the condition is something that refers to the present.

In Spanish, as in English, the si clause can either precede or follow the rest of the sentence. Thus a sentence such as si llueve voy de compras ("if it rains I'm going shopping") is the equivalent of voy de compras si llueve ("I'm going shopping if it rains").

Sample Sentences Using Si

Here are some examples of open conditions:

  • Si tengo dinero, me iré de viaje. (If I have money, I'll go on a trip. The fact of having money is seen as reasonably likely.)
  • Si la casa es usada, le aconsejamos que un profesional la inspeccione. (If the house is used, we advise that you have a professional inspect it. A sentence like this might be used in giving advice, where the condition here is seen as a real possibility.)
  • Si lo quieres, ¡pídelo! (If you want it, ask for it!)
  • Van a salir si el presidente y los otros ladrones ganan las elecciones. (They are going to leave if the president and the other thieves win the elections.)
  • Si sales, salgo también. (If you leave, I'm leaving too.)
  • Si gana Sam, voy a llorar. (If Sam wins, I'll cry.)

Here are some examples of unlikely or contrary-to-fact conditions:

  • Si yo fuera tú, tomaría una responsabilidad propia. (If I were you, I would take appropriate responsibility. There is no possibility that I will become you.)
  • Si yo tuviera dinero, iría al cine. (If I had the money, I would go to the movies. The speaker is saying she doesn't have the money. If the present tense were used, si tengo dinero, she would be saying there is a reasonable likelihood of having money.)
  • Mi hermana iría muchas veces a la playa si supiera nadar. (My sister would go to the beach often if she knew how to swim.)
  • Si ella hubiera tenido dinero, habría ido al cine. (If she had had the money, she would have gone to the movies.)
  • Si ganara Sam, lloraría. (If Sam were to win, I'd cry.)

A Quick Note About Writing

The word si should not be confused with sí, a common word of affirmation, often translated as "yes." The latter word is always spelled with a written or orthographic accent to distinguish the two, although they are pronounced identically.

Key Takeaways

  • When si (meaning "if") is followed by a verb, the verb is in the present indicative if the condition stated is true or probable.
  • When si is followed by a verb, the verb is in a past subjunctive if the condition stated is false or improbable.
  • The past subjunctive is used for improbabilities even if the condition stated is one that applies to the present time.