Spanish Si Clauses: If-Sentences from Real to Regret

Every si sentence has two parts: the condition (si…) and the result. What decides the verb forms is not tense rules you have to memorize one by one. It’s a single judgment about the condition:

✦The question✦

How real is this “if”?

Could genuinely happen: si + present indicative.
Imagined right now (it isn’t true): si + tuviera-form, result in -ría.
Imagined in the past (it didn’t happen): si + hubiera + past participle, result with habría.

Three rungs, from real to impossible. Here’s the whole ladder at a glance:

How Real?	The Si Part	The Result
Could happen	Si llueve…	no vamos / no iremos / no vayas
Imagined now	Si tuviera dinero…	viajaría
Imagined in the past	Si hubiera estudiado…	habría aprobado

1. Real Conditions

If the condition could genuinely happen, the si-clause takes the plain present indicative. The result can be in the present, future, or a command, depending on what you want to say.

Si llueve, no vamos. If it rains, we’re not going. result: present

Si estudias, aprobarás. If you study, you’ll pass. result: future

Si tienes tiempo, llámame. If you have time, call me. result: command

Si llueva, no vamos. The mistake WEIRDO tempts you into. Si never takes the present subjunctive. ❌ never

The WEIRDO Trap

WEIRDO teaches you to watch for uncertainty, so an “if” may feel like it should trigger the subjunctive. But si is different: in a real or possible condition, Spanish uses the present indicative after si — si llueve, si tienes, si estudias. Never si llueva.

2. Hypotheticals

Now imagine a condition that isn’t true: you don’t have the money, you aren’t me, we can’t fly. The si-clause takes the imperfect subjunctive (tuviera, fuera, pudiera), and the result takes the conditional (viajaría, haría). The pair always travels together:

Si tuviera dinero, viajaría por el mundo. If I had money (I don’t), I would travel the world. tuviera + viajaría

Si yo fuera tú, no lo haría. If I were you, I wouldn’t do it. fuera + haría

Si pudiéramos volar, no habría tráfico. If we could fly, there’d be no traffic. pudiéramos + habría

Si tendría dinero, viajaría. The most famous si-clause mistake: the conditional never goes in the si half. ❌ never

✦English Trap✦

English speakers sometimes say things like “if I would have…”, which makes si tendría feel natural. But Spanish splits a hypothetical into two jobs:

IF half → imperfect subjunctive: Si tuviera dinero…
THEN half → conditional: …viajaría.

The conditional expresses what would happen — the hypothetical result — so it belongs in the THEN half, not directly after si.

Como si

Como si (“as if”) is a close relative of hypothetical si because it also asks you to imagine something that isn’t being presented as true. You’re comparing reality to an unreal scenario: he looks at me as if I were an alien; she talks as if she knew everything.

Because that comparison is hypothetical, como si takes the subjunctive. Use the imperfect subjunctive when the imagined situation is happening at the same time:

Me mira como si fuera un extraterrestre. He looks at me as if I were an alien. como si + fuera

Habla como si supiera todo. She talks as if she knew everything. como si + supiera

Real Conditions in the Past

Real conditions aren’t limited to the present. You’ll also see sentences like:

Si tenía dinero, compraba dulces.
Whenever I had money, I bought candy.

That isn’t a hypothetical. It describes something that really happened repeatedly in the past, so Spanish stays in the indicative. A useful test: if you could replace si with “whenever,” you’re dealing with a real condition.

3. Unreal Past

The last rung is for unreal past conditions — things that didn’t happen, and the results that would have followed. Use hubiera + past participle in the si-clause, and habría + past participle in the result. It’s the same IF → THEN pattern as before, just shifted into the past.

Si hubiera estudiado, habría aprobado. If I had studied, I would have passed. (I didn’t study, so I didn’t pass.) hubiera + habría

Si hubieras venido, la habrías conocido. If you had come, you would have met her. hubieras + habrías

The logic is the same as rung two: the IF half imagines a different past, and the THEN half gives the result. So the same warning still applies: habría belongs in the result, not directly after si.

That’s the whole system: decide whether the condition is real, imagined now, or imagined in the past, and the rung gives you both verb forms. The Si Clauses decks drill each pairing until it becomes automatic. If the forms themselves are shaky, the Crash Course has dedicated lessons on the imperfect subjunctive and conditional.

Want the full conjugations and more examples? See the Imperfect Subjunctive crash-course lesson.