Si clauses: real and unreal conditions

The golden rule: no -ría after si

When si means if, standard Spanish never puts three things after it: a -ría form, a present subjunctive or the future. The -ría form belongs in the other half:

When si means whether

All of that is about si meaning if. When it means whether, in a reported question, any indicative tense goes, the future and the conditional included:

• No sé si vendrá. - I don't know whether he/she will come.
• Me preguntó si iría. - He/She asked me whether I would go.

Type 1: real conditions

When the if could really happen, use si + present. The result can be a present, a future or a command:

The if stays in the present even about tomorrow, as in English: Si llueve mañana... (If it rains tomorrow...).

A real if about the past takes a past indicative:

• Si lo dijo, es verdad. - If he/she said it, it's true.
• Si llovía, nos quedábamos en casa. - If it rained, we used to stay in.

Type 2: unreal now or future

When the if is only imagined, use si + imperfect subjunctive, then the conditional:

The -se form works here too, with the same meaning: Si yo tuviese dinero, viajaría. The result half has no -se option: it takes the -ría form. In relaxed speech you will also hear the imperfect there (Si tuviera dinero, me compraba un coche.), but the -ría form is always right.

The halves can swap, and the comma follows

The si half can come first or second, with the same meaning. When it comes first, a comma usually follows it; when it comes second, no comma:

• Si llueve, me quedo en casa. - If it rains, I stay at home.
• Me quedo en casa si llueve. - I stay at home if it rains.
• Viajaría si tuviera dinero. - I'd travel if I had money.