Conditional sentences with si

B1 Las oraciones condicionales con si 43 / 49

In short

A real or likely condition uses si + present indicative in the “if” part, and a present, future, or imperative in the result: Si llueve, me quedo en casa. The iron rule: si is never followed by the present subjunctive.

The rule

A conditional sentence has two halves: the condition (the si-clause, “if…”) and the result (the main clause). This lesson covers real / likely conditions — things that can plausibly happen.

Step 1 - The si-clause: present indicative. For a real condition, si (“if”) is followed by the present indicative, the tense you already know: Si estudias…, Si tengo tiempo…, Si hace sol….

The iron rule: after si meaning “if”, you never use the present subjunctive. Si tengas is always wrong; it must be Si tienes. This is the single most common English-speaker error, because English “if” feels tentative — Spanish si is not.

Step 2 - The result clause: present, future, or imperative. The main clause takes one of three forms, all natural:

Result form	Nuance	Example
Present indicative	a general truth / automatic result	Si llueve, me quedo en casa.
Future simple	a specific prediction	Si llueve, me quedaré en casa.
Imperative	advice / a command	Si llueve, quédate en casa.

All three keep the same si + present condition.

Step 3 - Order is free. Either half can come first. When the si-clause opens the sentence, separate the halves with a comma; when the result comes first, use no comma:

Si llueve, no salgo.
No salgo si llueve.

The short form si no. When the alternative is obvious from what was just said, the verb of the si-clause is dropped and only si no is left: Si el tiempo acompaña, comemos fuera; si no, comemos dentro. Keep it two words — sino, one word, is a different word meaning “but rather”.

si = “if” vs “whether”. si also means “whether” after verbs of knowing and asking. Here it is NOT a condition, and it can be followed by the future or the conditional: No sé si vendrá. (I don’t know whether he’ll come.) Pregúntale si quiere café.

Preview — unreal conditions. When the condition is hypothetical or contrary to fact (“If I had money…”), Spanish switches to si + imperfect subjunctive -> conditional: Si tuviera dinero, viajaría. That pattern is lesson 46; here we stay with real conditions.

Forms & patterns

Real-condition template:

Si-clause (condition)	Result clause
si + present indicative	present indicative
si + present indicative	future simple
si + present indicative	affirmative / negative imperative

The results built on one condition:

Condition	Result type	Full sentence
Si estudias	present	Si estudias, apruebas.
Si estudias	future	Si estudias, aprobarás.
Si estudias	affirmative imperative	Si estudias, descansa después.
Si estudias	negative imperative	Si estudias, no te acuestes tarde.
Si estudia (usted)	formal imperative	Si estudia, descanse después.

Any imperative can be the result — negative, formal (usted / ustedes) or vosotros. The negative and formal ones are present-subjunctive forms (lesson 41); that does not break the iron rule, which bans the present subjunctive only after si.

Examples

Español	English
Si llueve, me quedo en casa.	If it rains, I stay home.
Si tienes hambre, hay comida en la nevera.	If you’re hungry, there’s food in the fridge.
Si estudias más, aprobarás el examen.	If you study more, you’ll pass the exam.
Si vas al centro, cómprame el pan.	If you go downtown, buy me some bread.
No iré a la fiesta si no me invitan.	I won’t go to the party if they don’t invite me.
Si puedes, llámame esta noche.	If you can, call me tonight.
No sé si vendrá mañana.	I don’t know whether he’ll come tomorrow.
Pregúntale si quiere venir.	Ask him whether he wants to come.

Common mistakes

Si tengas tiempo, llámame -> Si tienes tiempo, llámame - si (“if”) is never followed by the present subjunctive; use the present indicative.
Si lloverá, me quedo -> Si llueve, me quedo - do not put the future in the si-clause; the future belongs to the result clause only.
Si estudiarás, aprobarás -> Si estudias, aprobarás - same point: si + present indicative, future only in the result.
No salgo, si llueve -> No salgo si llueve - when the result comes first, drop the comma; use a comma only when si opens the sentence.
No sé si venga -> No sé si vendrá - here si means “whether”, not a condition; use the indicative (future / conditional), never the subjunctive.

Tips

Chant the iron rule: “si + present indicative” for real conditions. If you’re tempted to write si tenga, stop - it’s si tengo.
English hides the tense: “If it rains tomorrow” is present in Spanish too (Si llueve mañana), never the future.
The result clause is where the future lives: Si + present, … + future.
To decide “if” vs “whether”, try swapping in “whether”. If it fits (“I don’t know whether…”), it’s the reporting si, not a condition.
Dreamy, unreal conditions (“If I were rich…”) jump to the imperfect subjunctive - that’s lesson 46, not this pattern.