First conditional (if present, then future/imperative) - Spanish Grammar

What is the first conditional in Spanish?

The first conditional in Spanish expresses a real, likely condition and its probable result in the future. In English it corresponds to "If + present simple → will + verb" (for example, "If it rains, I will stay home"). In Spanish the usual pattern is:

- si + present indicative (condition) → main clause with a future-like form (futuro simple / ir a + infinitive) or an imperative (command) or sometimes the present indicative for near/planned actions.

Example (English-style):
- Si llueve, me quedaré en casa. (If it rains, I will stay at home.)

When do I use the first conditional?

To talk about likely future outcomes

If the condition is realistic or possible, use the first conditional to say what will probably happen.

Si estudias, aprobarás el examen. (If you study, you will pass the exam.)

To give instructions, advice or warnings depending on a condition

Use si + present to introduce the condition and an imperative or polite command in the result.

Si tienes hambre, come algo. (If you're hungry, eat something.)
Si necesita ayuda, llame al + teléfono. (If you need help, call this number.)

To make promises or threats about the future

Si vienes, te ayudaré. (If you come, I will help you.)

How do I form the first conditional?

1) The si-clause (condition): always si + present indicative

The condition is expressed with si + present indicative (no subjunctive for normal likely future conditions):

Si + yo/ tú/ él / nosotros / vosotros / ellos (present indicative)

Examples with conjugations (present indicative):
- hablar: si hablo, si hablas, si habla, si hablamos, si habláis, si hablan
- comer: si como, si comes, si come, si comemos, si coméis, si comen
- venir: si vengo, si vienes, si viene, si venimos, si venís, si vienen

Examples:
- Si llegas temprano, te ayudaré. (If you arrive early, I'll help you.)
- Si tienes dudas, pregunta. (If you have doubts, ask.)

2) The main clause (result): common options

You can express the result in several natural ways. All are used in first-conditional contexts.

a) Futuro simple (futuro de indicativo)
- Structure: main clause uses futuro simple (hablaré, hablarás, hablará...)
- Example: Si estudias, aprobarás. (If you study, you will pass.)

b) Periphrasis "ir a + infinitive" (going-to future)
- Structure: main clause uses "ir a + infinitive" to express planned or likely future (voy a, vas a...)
- Example: Si estudias, vas a aprobar. (If you study, you're going to pass.)

c) Imperative (commands or instructions)
- Use an imperative when the result is an instruction or advice: Si + present → imperative (tú / usted / ustedes / vosotros). Note negative commands use the present subjunctive form (no + subjunctive).
- Affirmative tú example: Si tienes tiempo, ven a verme. (If you have time, come see me.)
- Negative tú example: Si no lo entiendes, no lo hagas. (If you don't understand it, don't do it.)
- Formal usted example: Si necesita ayuda, hable con el recepcionista. (If you need help, speak with the receptionist.)

d) Present indicative for near or planned actions
- Spanish often uses the present indicative in the main clause to express future when the event is planned or certain.
- Example: Si vienes mañana, hablamos por la tarde. (If you come tomorrow, we'll talk in the afternoon.)

e) Future perfect (to show something will have happened by a future time)
- Example: Si terminas antes, ya habré salido. (If you finish earlier, I will have already left.)

3) Word order and punctuation

If the si-clause comes first, use a comma: Si llegas tarde, no te preocupes.
If the main clause comes first, no comma is necessary: No te preocupes si llegas tarde.
Both orders are common and correct; meaning stays the same.

Examples: many useful first-conditional sentences (grouped by type)

Future simple in the main clause

Si estudias, aprobarás el examen. (If you study, you'll pass the exam.)
Si no llueve, iremos al parque. (If it doesn't rain, we will go to the park.)
Si me llamas, te responderé. (If you call me, I will answer you.)
¿Qué harás si te ofrecen el puesto? (What will you do if they offer you the job?)

Periphrastic future (ir a + infinitive)

Si practicas cada día, vas a mejorar mucho. (If you practice every day, you're going to improve a lot.)
Si me avisas, voy a comprar las entradas. (If you let me know, I'm going to buy the tickets.)

Imperative (instructions and advice)

Si tienes hambre, come algo. (If you're hungry, eat something.)
Si te pierdes, llámame. (If you get lost, call me.)
Si no sabes la respuesta, no la inventes. (If you don't know the answer, don't make one up.)
Si necesita ayuda, llame al mostrador. (If you need help, call the desk.)

Present indicative in the main clause (planned/near future)

Si vienes mañana, hablamos por la tarde. (If you come tomorrow, we'll talk in the afternoon.)
Si llegas tarde, te esperamos. (If you arrive late, we'll wait for you.)

Future perfect (to show something will have occurred)

Si llegas antes de las diez, ya habré salido. (If you arrive before ten, I will already have left.)

Negative conditions and commands

Si no estudias, suspenderás. (If you don't study, you'll fail.)
Si no quieres venir, no vengas. (If you don't want to come, don't come.)
Si no traes casco, no subas a la moto. (If you don't bring a helmet, don't get on the motorcycle.)

Common mistakes and how to avoid them

Mistake: Using the conditional in the si-clause

Wrong: Si tendría tiempo, iría al cine. (incorrect) Correct for hypothetical: Si tuviera tiempo, iría al cine. (If I had time, I would go to the movies.) — this is the second conditional (improbable/hypothetical), not the first conditional. For first conditional (real possibility) use si + present.

Mistake: Using present subjunctive in the si-clause for likely conditions

Wrong: Si llegue a las nueve, te llamo. (incorrect) Correct: Si llegas a las nueve, te llamaré. (If you arrive at nine, I will call you.) Note: "si" normally takes the indicative for real/possible conditions. Subjunctive in "si" clauses is used only in hypothetical (e.g., Si tuviera...) or very formal/rare uses.

Mistake: Confusing "si" with time conjunctions like "cuando"

Use "si" for conditions (If...).
Use "cuando" for time (When...), and with future reference Spanish usually uses the subjunctive after "cuando":
Si llegas, te llamo. (If you arrive, I'll call you.) — si + present indicative.
Cuando llegues, te llamaré. (When you arrive, I'll call you.) — cuando + present subjunctive (because it is a future event).

Mistake: Translating English "would" directly into Spanish si-clauses

Wrong: Si voy, te llamaría. (incorrect if you mean a real future condition) Correct: Si voy, te llamaré. (If I go, I'll call you.) (Remember: "would" in English often corresponds to the Spanish conditional in hypothetical situations, not in a true first conditional.)

Related structures learners often confuse with the first conditional

Zero conditional / general truths (both clauses in present)

Use present + present to state general truths or scientific facts.
Example: Si calientas el agua, hierve. (If you heat water, it boils.) — not a first conditional about the future, but a general truth.

Second conditional / hypothetical present (si + past subjunctive → conditional)

Use for unlikely or hypothetical situations now or in the future.

Example: Si tuviera dinero, compraría un coche. (If I had money, I would buy a car.)

Time conjunctions (cuando, en cuanto, tan pronto como) vs "si"

These conjunctions often require subjunctive when they refer to future events: Cuando llegues, empezamos → Cuando llegues, empezaremos. (When you arrive, we'll start.)
Do not replace "si" with "cuando" unless the meaning is time rather than condition.

"Por si" (just in case) is similar but not the same

Por si + present: used to mean "just in case". The clause after "por si" often uses present indicative too.
Example: Lleva un paraguas por si llueve. (Take an umbrella just in case it rains.)

Quick reference: short rules and quick examples

Structure: si + present indicative → futuro simple / ir a + infinitive / imperative / present (for planned actions).
Si estudias, aprobarás. (futuro simple)
Si estudias, vas a aprobar. (ir a + infinitive)
Si tienes hambre, come algo. (imperative)
Si vienes mañana, hablamos. (present used for planned action)
If the si-clause comes first, use a comma.
Don’t put a conditional (would/iría) in the si-clause for first conditional.
Negative commands use subjunctive: Si no quieres, no vengas.

Glossary (simple definitions)

si: the conjunction "if" (note: not to be confused with "sí" meaning "yes").
Present indicative: the normal "present" tense (yo hablo, tú comes).
Futuro simple: simple future tense (yo hablaré, tú comerás).
Ir a + infinitive: periphrastic future (voy a hablar = I am going to speak).
Imperative: command form (habla = speak!, no hables = don't speak).
Subjunctive: a mood used in Spanish for wishes, doubts, unreal situations (used in some si-clauses for hypotheticals: Si tuviera...).
Conditional: would + verb in English; in Spanish it’s the conditional tense (yo iría = I would go).

If you want, I can add: a short conjugation table for a sample verb, a list of common irregular imperatives, or audio examples to practise these structures.