Unreal conditionals (if + past subjunctive)

What are unreal conditionals using 'si' + past subjunctive?

An unreal (or counterfactual) conditional with "si + past subjunctive" is a Spanish structure used to talk about situations that are hypothetical, improbable, or contrary to the present reality. In English it usually translates as "If + past (or were) ... , would + verb ..."

Example:
Si tuviera dinero, compraría un coche. (If I had money, I would buy a car.) — but I don't have money now.

This pattern is the standard way to talk about unreal conditions about the present or future (things that are not true now or are unlikely to happen).

When do I use si + past subjunctive?

Use this structure when:
- You imagine a situation that is not true now: "Si fuera rico..." (If I were rich...).
- You describe an unlikely or improbable future: "Si ganara la lotería, me mudaría a España." (If I won the lottery, I'd move to Spain.)
- You give hypothetical advice: "Si yo fuera tú, no lo haría." (If I were you, I wouldn't do it.)

Compare with a real/possible condition (not unreal):
- Real condition: Si tengo tiempo, iré al cine. (If I have time, I'll go to the cinema.) — present indicative + future.
- Unreal condition: Si tuviera tiempo, iría al cine. (If I had time, I would go to the cinema.) — imperfect subjunctive + conditional.

How do I form the past subjunctive (pretérito imperfecto de subjuntivo)?

Step-by-step (the -ra form, most common):
1. Take the ellos/ustedes form of the preterite (third person plural). Example: hablaron, comieron, vivieron.
2. Drop the -ron ending: habla-, comie-, vivie-.
3. Add the imperfect-subjunctive endings: -ra, -ras, -ra, -ramos, -rais, -ran.

Examples (regular verbs):
- hablar -> hablaron -> hablara, hablaras, hablara, habláramos, hablarais, hablaran.
- comer -> comieron -> comiera, comieras, comiera, comiéramos, comierais, comieran.
- vivir -> vivieron -> viviera, vivieras, viviera, viviéramos, vivierais, vivieran.

Alternative (-se) form:
Spanish also has a second set of imperfect-subjunctive endings: -se, -ses, -se, -semos, -seis, -sen. Both forms are correct and interchangeable in meaning.
Examples: tuviera / tuviese, fuera / fuese, pudiera / pudiese.

Common irregulars (imperfect subjunctive -ra form):
- ser / ir: fuera, fueras, fuera, fuéramos, fuerais, fueran.
- tener: tuviera, tuvieras, tuviera, tuviéramos, tuvierais, tuvieran.
- poder: pudiera, pudieras, pudiera, pudiéramos, pudierais, pudieran.
- hacer: hiciera, hicieras, hiciera, hiciéramos, hicierais, hicieran.
- venir: viniera, vinieras, viniera, viniéramos, vinierais, vinieran.
- decir: dijera, dijeras, dijera, dijéramos, dijerais, dijeran.

How do I form the conditional (main clause)?

The result clause (main clause) normally uses the conditional simple (condicional simple) to express "would + verb".

Formation: add conditional endings to the infinitive: -ía, -ías, -ía, -íamos, -íais, -ían.
Examples:
- comprar -> compraría, comprarías, compraría, compraríamos, compraríais, comprarían.
- ser -> sería, serías, sería, seríamos, seríais, serían.

Some common irregular conditional stems:
- decir -> diría
- hacer -> haría
- tener -> tendría
- poner -> pondría
- poder -> podría
- salir -> saldría
- venir -> vendría
- querer -> querría
- saber -> sabría

So the full unreal-present/future pattern is:
Si + imperfect subjunctive (past subjunctive) ---> conditional simple.

Order of clauses and punctuation

- If the si-clause comes first, put a comma: Si tuviera tiempo, viajaría más.
- If the main clause (the conditional) comes first, no comma is needed: Viajaría más si tuviera tiempo.

Both orders are grammatically correct and mean the same thing.

Common mistakes to avoid

- Wrong: *Si tendría dinero, compraría un coche.*
Correct: Si tuviera dinero, compraría un coche.
(Do not use the conditional in the si-clause.)

- Wrong: *Si tenía dinero, compraría un coche.*
Correct (real past habit): Si tenía dinero, compraba coches. / (unreal present): Si tuviera dinero, compraría un coche.
(Using the imperfect indicative changes the meaning.)

- Wrong: *Si tuviera dinero, compraré un coche.*
Correct: Si tuviera dinero, compraría un coche.
(Don't mix imperfect subjunctive with future simple when you mean an unreal present/future.)

- Confusing present unreal vs past unreal:
- Present/future unreal (now contrary to fact): Si tuviera dinero, compraría un coche.
- Past unreal (contrary to past fact): Si hubiera tenido dinero, habría comprado un coche.
(Use pluperfect subjunctive "hubiera + past participle" + conditional perfect "habría + past participle" for past counterfactuals.)

Examples of improbable present/future conditions

Here are many natural examples (Spanish first, then a short translation):

- Si tuviera dinero, compraría un coche. (If I had money, I would buy a car.)
- Si fuera rico, viajaría por todo el mundo. (If I were rich, I would travel the world.)
- Si pudiera volar, iría a París mañana. (If I could fly, I would go to Paris tomorrow.)
- Si ganara la lotería, me mudaría a España. (If I won the lottery, I'd move to Spain.)
- Si vinieras ahora, te ayudaría. (If you came now, I'd help you.)
- Si lo supiera, te lo diría. (If I knew it, I'd tell you.)
- Si yo fuera tú, no lo haría. (If I were you, I wouldn't do it.)
- Si no lloviera mañana, haríamos un picnic. (If it didn't rain tomorrow, we'd have a picnic.)
- Si nos dieran más tiempo, terminaríamos el proyecto. (If they gave us more time, we'd finish the project.)
- Si tuviese dinero, compraría una casa en la playa. (If I had money, I'd buy a beach house.) — using the -se form (tuviese) is also correct.
- Compraríamos un coche si tuviéramos dinero. (We would buy a car if we had money.) — main clause first, no comma.
- Si él fuera famoso, recibiría muchas cartas. (If he were famous, he'd receive many letters.)
- Si me invitaras, iría a la fiesta. (If you invited me, I would go to the party.)
- Si supieras la verdad, te sorprenderías. (If you knew the truth, you'd be surprised.)

These all describe present or future situations that are not true now or are unlikely to happen.

Short glossary

- si-clause: the clause that begins with "si" (if). Example: "Si tuviera tiempo...".
- imperfect subjunctive / pretérito imperfecto de subjuntivo: the "past subjunctive" verb form used after "si" for unreal present/future conditions (tuviera, fuera, pudiera).
- conditional simple / condicional simple: the "would" verb form used in the main clause (compraría, sería, podría).
- pluperfect subjunctive / pretérito pluscuamperfecto de subjuntivo: "hubiera + past participle" — used for unreal past conditions.
- conditional perfect / condicional compuesto: "habría + past participle" — result for unreal past conditions.
- counterfactual / unreal: a situation that is imagined and known (by the speaker) not to be true.

Quick summary / cheat-sheet

- Present/future unreal (main topic here):
Si + imperfect subjunctive (tuviera, fuera, pudiera) → conditional simple (compraría, sería, podría).
Example: Si tuviera tiempo, viajaría más.

- Past unreal (for reference):
Si + pluperfect subjunctive (hubiera + past participle) → conditional perfect (habría + past participle).
Example: Si hubiera estudiado, habría pasado el examen.

Final tip: Think in English equivalents to check meaning: if the English sentence uses "If I were... / If I had..., I would...", use si + past subjunctive → conditional in Spanish. Avoid putting a conditional form inside the si-clause.

If you want, I can also give a short conjugation chart for a few verbs or show more examples focused on specific verbs (tener, ser, poder, venir).