The si clause is the workhorse of conditional sentences in Spanish, and it handles the vast majority of real-life conditions. But Spanish also has a set of alternative conditional structures — some formal, some literary, some used every day in casual speech — that replace si with a preposition plus an infinitive. These structures are extremely common in written Spanish and in educated speech, and understanding them is essential for advanced reading comprehension and for producing natural-sounding formal language.
This page covers four main alternatives: de + infinitive, a + infinitive, con + infinitive, and the gerund as conditional. Each has its own nuances, and knowing when to reach for each one will make your Spanish more precise and more flexible.
De + infinitive: the formal conditional
This is the most important alternative conditional structure. It replaces si clauses — particularly Type 3 (unreal past) conditionals — and is a hallmark of formal writing, journalism, and educated speech.
De + simple infinitive (present/future condition)
De no estar de acuerdo, pueden presentar una queja formal.
If you don't agree, you can file a formal complaint.
The simple infinitive after de typically corresponds to a present or hypothetical condition — equivalent to si tuviera, si fuera, si no estuvieran.
De + compound infinitive (past unreal condition)
When the condition is about the past and counterfactual, use de haber + past participle. This is the infinitive equivalent of a Type 3 conditional.
De haberlo sabido, no habría venido.
Had I known, I wouldn't have come.
De haber tenido más tiempo, habríamos terminado el proyecto.
If we had had more time, we would have finished the project.
De haber estudiado más, habría aprobado el examen.
If I had studied more, I would have passed the exam.
De no ser por: "if it weren't for"
This negative construction is extremely common in both formal and semiformal Spanish:
De no ser por la lluvia, habríamos ido a la playa.
If it weren't for the rain, we would have gone to the beach.
De no ser por tu ayuda, no habría podido terminar.
If it weren't for your help, I wouldn't have been able to finish.
A + infinitive: conditional with evaluative force
The a + infinitive construction has a narrower range than de + infinitive. It appears mainly in fixed or semi-fixed expressions, often with a sense of "judging by" or "if one were to."
A juzgar por su expresión, no le gustó la noticia.
Judging by his expression, he didn't like the news.
A no ser por el tráfico, habríamos llegado a tiempo.
If it hadn't been for the traffic, we would have arrived on time.
The most important patterns here are a juzgar por (judging by), a decir verdad (to tell the truth), and a no ser que (unless — always followed by subjunctive). These are essentially fixed phrases that you should learn as units.
Con + infinitive: sufficiency and minimal condition
Con + infinitive expresses a sufficient condition — "all it takes is" or "just by doing X." The implied meaning is that the action in the infinitive is enough, by itself, to produce the result.
Con estudiar un poco cada día, vas a aprobar.
Just by studying a little each day, you'll pass.
Con salir temprano, llegamos a tiempo.
If we just leave early, we'll arrive on time.
Con que me avises un día antes, es suficiente.
As long as you let me know a day before, that's enough.
Note the related construction con que + subjunctive, which means "as long as" or "provided that":
Con que no llueva, podemos hacer la fiesta afuera.
Provided that it doesn't rain, we can have the party outside.
Gerund as conditional
The gerund can express a condition, particularly in casual and semiformal speech. This use is more common in Latin America than in Spain.
Estudiando más, aprobarías sin problema.
If you studied more, you'd pass without a problem.
Saliendo a las seis, llegamos antes de las ocho.
If we leave at six, we'll arrive before eight.
Hablando con sinceridad, todo se resuelve más rápido.
If you speak honestly, everything gets resolved faster.
The gerund-as-conditional is informal and often ambiguous — it can also be interpreted as manner ("by studying more") or time ("when studying more"). Context usually clarifies the reading, but in formal writing, prefer de + infinitive or si clauses for clarity.
Comparison table
| Structure | Meaning | Register | Example |
|---|---|---|---|
| si + indicative/subjunctive | general conditional | all registers | Si tuviera tiempo, te ayudaría. |
| de + infinitive | formal conditional | formal / written | De tener tiempo, te ayudaría. |
| de + compound infinitive | past unreal conditional | formal / written | De haberlo sabido, no habría venido. |
| a no ser que + subj. | unless | formal | A no ser que llueva, iremos. |
| con + infinitive | sufficient condition | neutral | Con estudiar, apruebas. |
| con que + subjunctive | as long as | neutral | Con que vengas, me conformo. |
| gerund | informal conditional | informal | Estudiando más, aprobarías. |
Register considerations
The different conditional structures are not just grammatically interchangeable — they signal different levels of formality and different rhetorical effects:
- Si clauses are universal: acceptable everywhere, required nowhere specifically.
- De + infinitive sounds polished, professional, slightly literary. Use it in essays, presentations, journalism, and formal emails.
- Con + infinitive is relaxed and practical. It implies efficiency: "this is all you need to do."
- A no ser que is the formal way to say "unless." In casual speech, most people say a menos que or just si no.
- Gerund as conditional is casual and slightly ambiguous. Good for conversation, risky in formal writing.
Si hubiera llegado antes, habría conseguido asiento. (neutral)
If I had arrived earlier, I would have gotten a seat.
De haber llegado antes, habría conseguido asiento. (formal)
Had I arrived earlier, I would have gotten a seat.
Llegando antes, habrías conseguido asiento. (informal)
If you'd arrived earlier, you would have gotten a seat.
Common mistakes
Using de + conjugated verb instead of infinitive:
De sabía la verdad, te la habría dicho.
Incorrect. De takes only infinitives: De saber la verdad, te la habría dicho.
The de conditional only works with infinitives — never with conjugated verbs.
Forgetting the compound infinitive for past counterfactuals:
De saber eso ayer, no habría ido.
Technically possible but imprecise. Better: De haber sabido eso ayer, no habría ido.
When the condition is clearly about the past, use de haber + participle to make the time reference explicit.
Overusing gerund-as-conditional in formal writing:
Implementando estas medidas, se reduciría el déficit.
Acceptable in speech but vague in formal writing. Better: De implementar estas medidas, se reduciría el déficit.
The gerund is ambiguous between conditional, temporal, and manner readings. In formal contexts, use de + infinitive for clarity.
Confusing con + infinitive with con que + subjunctive:
Con que estudias un poco, apruebas.
Incorrect. Con que takes subjunctive: Con que estudies un poco, apruebas.
After con que (as long as), always use the subjunctive.
Related pages
For the standard si clause system, see Type 3 Conditionals and Mixed Conditionals. For absolute constructions that use similar infinitive and participial patterns, see Absolute Constructions.
Related Topics
- Type 3: Contrary-to-Fact PastC1 — Use the pluperfect subjunctive with the conditional perfect to talk about past situations that didn't actually happen.
- Mixed ConditionalsC1 — Combine past and present in a single conditional to talk about how what didn't happen then still shapes how things are now.
- Absolute ConstructionsC1 — Non-finite clauses with their own subject — participial, gerundial, and infinitive absolutes used to express time, cause, and conditions in formal Spanish.
- Si-Clauses Type 3C1 — Talk about things that didn't happen using the pluperfect subjunctive and the conditional perfect.