grammar.clauses.si-past-unreal
Lost pasts: si hubiera sabido, habría venido
Unreal past conditions: si + pluperfect subjunctive + conditional perfect: si hubiera sabido, no habría firmado. Spoken Spanish often doubles the hubiera.
grammarB2, C1v0.1.0
Explicación
The full frame: si + hubiera/hubiese + participle, then habría + participle: si hubiéramos comprado en 2020, habríamos ganado el doble.
Colloquially the main clause also takes hubiera: si hubiera sabido, no hubiera venido — accepted and extremely common. Mixed time works too: si hubiera estudiado medicina, ahora ganaría más.
Ejemplos
Si me hubieras avisado, te esperaba.
If you had told me, I'd have waited for you.
If you had told me, I'd have waited for you.
Región: global
Si no hubiera sido por vos, no lo lograba.
If it hadn't been for you, I wouldn't have made it.
If it hadn't been for you, I wouldn't have made it.
Región: global