Conditional Sentences (Si clauses) in Spanish

Overview

Conditional sentences -- "if...then..." constructions -- are one of the most powerful tools in any language. They let you talk about real possibilities, hypothetical scenarios, and imaginary situations. In Spanish, these are called oraciones condicionales and are built around the conjunction si (if).

At the B1 level, you will learn the two most important types of conditional sentences. The first conditional (real/open conditions) deals with things that could genuinely happen: "If it rains, I'll stay home." The second conditional (unreal/hypothetical conditions) deals with things that are unlikely or contrary to present reality: "If I were rich, I would travel the world."

The key challenge is pairing the right tenses in each clause. Spanish has strict rules about which tenses can follow si, and breaking these rules is one of the most noticeable errors a learner can make.

How It Works

Type 1: Real/Open Conditions (First Conditional)

These describe situations that are possible or likely. The si clause uses the present indicative, and the result clause uses the future, present, or imperative.

Pattern	Example	Translation
Si + present → future	Si vienes, estaré contento.	If you come, I'll be happy.
Si + present → present	Si llueve, no salgo.	If it rains, I don't go out.
Si + present → imperative	Si tienes hambre, come algo.	If you're hungry, eat something.
Si + present → ir a + inf	Si hace sol, vamos a ir a la playa.	If it's sunny, we're going to go to the beach.

Type 2: Unreal/Hypothetical Conditions (Second Conditional)

These describe situations that are unlikely, imaginary, or contrary to current reality. The si clause uses the imperfect subjunctive, and the result clause uses the simple conditional.

Pattern	Example	Translation
Si + imperf. subj. → conditional	Si tuviera dinero, viajaría.	If I had money, I would travel.
Si + imperf. subj. → conditional	Si fuera rico, compraría una casa.	If I were rich, I would buy a house.
Si + imperf. subj. → conditional	Si pudiera, te ayudaría.	If I could, I would help you.

Useful Related Expressions

Expression	Example	Translation
por si acaso	Lleva paraguas por si acaso llueve.	Take an umbrella just in case it rains.
como si + imperf. subj.	Habla como si supiera todo.	He speaks as if he knew everything.
si yo fuera tú	Si yo fuera tú, no iría.	If I were you, I wouldn't go.
a menos que + subj.	Iré a menos que llueva.	I'll go unless it rains.

What You CANNOT Do After Si

Never use	Example of error
Future after si	Si vendrás...
Conditional after si	Si tendrías dinero...
Present subjunctive after si	Si vengas...

Exception: Si meaning "whether" (not "if") can be followed by the future: No sé si vendré (I don't know whether I'll come).

Clause Order

Both orders work. When the si clause comes first, a comma separates the clauses:

Order	Example
Si clause first	Si tuviera tiempo, viajaría.
Result clause first	Viajaría si tuviera tiempo.

Examples in Context

Spanish	English	Note
Si vienes, estaré contento.	If you come, I'll be happy.	Type 1: real possibility
Si tuviera dinero, viajaría.	If I had money, I would travel.	Type 2: hypothetical
Si fuera rico, compraría una casa.	If I were rich, I would buy a house.	Type 2: contrary to fact
Por si acaso llueve, lleva paraguas.	In case it rains, take an umbrella.	por si acaso
Si hace buen tiempo, iremos a la playa.	If the weather is nice, we'll go to the beach.	Type 1
Si yo fuera tú, estudiaría más.	If I were you, I would study more.	Advice
Si pudieras elegir, ¿dónde vivirías?	If you could choose, where would you live?	Hypothetical question
Si me llamas, te cuento todo.	If you call me, I'll tell you everything.	Type 1, present → present
Habla como si fuera un experto.	He speaks as if he were an expert.	como si + imperf. subj.
No iría si no me invitaran.	I wouldn't go if they didn't invite me.	Type 2, reversed order

Common Mistakes

Using the conditional in the si-clause

• Wrong: Si tendría dinero, viajaría.
• Right: Si tuviera dinero, viajaría.
• Why: The conditional never follows si in standard Spanish. The si clause takes either the present indicative (Type 1) or the imperfect subjunctive (Type 2). The conditional goes only in the result clause.

Using the future in the si-clause

• Wrong: Si vendrás, te esperaré.
• Right: Si vienes, te esperaré.
• Why: The future tense cannot follow si in conditional sentences. Use the present indicative for real conditions.

Using the present subjunctive after si

• Wrong: Si tengas tiempo, ven.
• Right: Si tienes tiempo, ven.
• Why: The present subjunctive is not used after si in conditional sentences. For real conditions, use the present indicative. For hypothetical ones, use the imperfect subjunctive.

Mixing Type 1 and Type 2 patterns

• Wrong: Si tengo dinero, viajaría. (present + conditional)
• Right: Si tengo dinero, viajaré. (Type 1) or Si tuviera dinero, viajaría. (Type 2)
• Why: The tenses in each clause must match the same conditional type. Do not mix a Type 1 si-clause with a Type 2 result clause.

Usage Notes

In everyday spoken Spanish, Type 1 conditionals are extremely common and are used in all registers and regions. Type 2 conditionals are also very frequent, especially for giving advice (Si yo fuera tú...), expressing wishes (Si pudiera...), and discussing hypothetical scenarios.

The expression como si (as if) always takes the imperfect subjunctive: Se comporta como si no pasara nada (He behaves as if nothing were happening). This is a firm rule with no exceptions.

In some colloquial speech, particularly in parts of Spain and Latin America, you may hear the imperfect indicative used in both clauses instead of the standard Type 2: Si tenía dinero, viajaba. While understood, this is considered non-standard.

The expression por si acaso (just in case) is very common and takes either the present indicative (por si acaso llueve) or the imperfect subjunctive (por si acaso lloviera), with the present being more common in speech.

At the B2 level, you will learn the third conditional for past hypotheticals (Si hubiera sabido, habría venido), but mastering Types 1 and 2 first provides a solid foundation.

Practice Tips

• Create "What would you do if..." conversations with a partner: ¿Qué harías si ganaras la lotería? ¿Si pudieras viajar a cualquier lugar? These are fun and provide extensive conditional practice.
• Practice the golden rule: never put the conditional or future after si. If you can internalize this one rule, you will avoid the most common error.
• Use si yo fuera tú to practice giving advice: Si yo fuera tú, hablaría con ella. Si yo fuera tú, no me preocuparía.

Related Concepts

• Prerequisite: Simple Conditional