si — the three conditional types

and the rule that is never brokenB1

In one line

Three fixed combinations, and after si you never use a future or a conditional.

The forms on this page

FormMeansSound
siif — and before il it becomes s'il/si/

The table

TypeAfter siThe other clauseMeaningPronunciation
1 — possiblepresentfutureSi tu viens, je serai content. if you come, I'll be happy/si ty vjɛ̃ ʒə sə.ʁe kɔ̃.tɑ̃/
2 — hypotheticalimperfectpresent conditionalSi tu venais, je serais content. if you came, I'd be happy/si ty və.nɛ ʒə sə.ʁɛ kɔ̃.tɑ̃/
3 — impossiblepluperfectpast conditionalSi tu étais venu, j'aurais été content. if you had come, I'd have been happy — but you didn't/si ty e.tɛ və.ny ʒo.ʁɛ.z‿e.te kɔ̃.tɑ̃/

All three are fixed. There is no other combination.

English teaches exactly the same three types, in the same order, with the same backshift — first, second and third conditional. The tenses match one for one:

EnglishFrench
1if you come, I will besi tu viens, je serai
2if you came, I would besi tu venais, je serais
3if you had come, I would have beensi tu étais venu, j'aurais été

So there is nothing new to understand here — only the forms to produce.

The rule that is never broken

After si, never -rai or -rais

❌✅
Si tu viendrasSi tu viens
Si tu viendraisSi tu venais

The future and the conditional appear only in the other clause, never after si.

English obeys the same ban and you obey it without thinking. "If you will come" and "if you would come" are both wrong in the same way. So this rule costs you nothing — but it is the single most common mistake French speakers make in their own language, which tells you how strong the pull is.

And the order of the two clauses is free

Pronunciation
Si tu viens, je serai content./si ty vjɛ̃ ʒə sə.ʁe kɔ̃.tɑ̃/
Je serai content si tu viens.the same meaning — and no comma here/ʒə sə.ʁe kɔ̃.tɑ̃ si ty vjɛ̃/

English does the same, with the same comma rule.

Exceptions

ExceptionWhat happens
Type 1 can also take a present or an imperativeSi tu veux, viens. /si ty vø vjɛ̃/
Si tu chauffes l'eau, elle bout. /si ty ʃof lo ɛl bu/
si /si/ meaning "whether" follows a different rulethere the future is allowed — see the indirect-question page
si /si/ + il /il/ elidess'il /sil/ — but not si elle /si ɛl/
Type 3 sometimes has a present resultSi j'avais étudié, je serais médecin maintenant. /si ʒa.vɛ.z‿e.ty.dje ʒə sə.ʁɛ me.də.sɛ̃ mɛ̃t.nɑ̃/

That second row matters more than it looks. English uses "if" for both meanings too — "if it rains" (condition) and "I don't know if he's coming" (whether). French uses si for both as well, but only the conditional one bans the future. Je ne sais pas s'il viendra is correct.

Examples

EnglishFrenchPronunciation
If I have time, I'll comeSi j'ai le temps, je viendrai./si ʒe lə tɑ̃ ʒə vjɛ̃.dʁe/
If I had money, I'd travelSi j'avais de l'argent, je voyagerais./si ʒa.vɛ də laʁ.ʒɑ̃ ʒə vwa.ja.ʒə.ʁɛ/
If I had known, I'd have comeSi j'avais su, je serais venu./si ʒa.vɛ sy ʒə sə.ʁɛ və.ny/
If you want, comeSi tu veux, viens./si ty vø vjɛ̃/
If it rains, I won't go outS'il pleut, je ne sortirai pas./sil plø ʒə nə sɔʁ.ti.ʁe pa/

Common mistakes

❌✅Why
Si tu viendras, je serai content.Si tu viens, …No future after si
Si tu viendrais, je serais content.Si tu venais, …No conditional after si
Si j'aurais su.Si j'avais su.The same rule — and the most common error French speakers make
Si il pleut.S'il pleut.si + il elides
Si tu venais, je viendrai.… je viendrais.Type 2 pairs with the present conditional

How to hold it

three pairs, each one step further back

Look at the pattern — each type steps one tense further back:

Typesi +→
1presentfuture
2imperfect (one step back)present conditional
3pluperfect (two steps back)past conditional

English does the identical backshift and you already feel it:

"if you come, I will be glad"possible
"if you came, I would be glad"hypothetical
"if you had come, I would have been glad"impossible

Notice that English also uses a past tense for a present hypothesis — "if I were rich" is about now, not the past. French does exactly the same with the imperfect.

So the meanings transfer completely. The one genuinely new thing is that French forbids the future after si — and, unlike in English, that rule is enforced strictly enough to cost marks.

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