A future before the future
Two things lie ahead: first you finish, then you call. Both are in the future, but one comes first. The futur antérieur is what makes that order visible: Quand j'aurai fini, je t'appellerai. Like the plus-que-parfait, it sits before another point in time, only here the whole scene is in the future.
The forms
finir and partir
| Person | finir | partir |
|---|---|---|
| je | aurai fini | serai parti(e) |
| tu | auras fini | seras parti(e) |
| il / elle / on | aura fini | sera parti(e) |
| nous | aurons fini | serons parti(e)s |
| vous | aurez fini | serez parti(e)(s) |
| ils / elles | auront fini | seront parti(e)s |
Futur antérieur with both auxiliaries
After quand, dès que, une fois que
This is the main use. When both actions lie in the future, quand, lorsque, dès que, aussitôt que, une fois que, après que are followed by a future form: the futur antérieur when the action in the subordinate clause is finished first.
English uses a present or present perfect after when: when I finish, as soon as we have eaten, never a future. That is why a present tense slips so easily into French here.
One thing, then the other
Quand j'aurai fini, je t'appellerai.
When I've finished, I'll call you.
Dès qu'ils seront arrivés, on passera à table.
As soon as they've arrived, we'll sit down to eat.
Une fois que tu auras signé, tout ira vite.
Once you've signed, everything will move fast.
If both things happen at the same time, the subordinate clause takes the futur simple too: Quand tu seras à Paris, tu verras la Seine. You only need the futur antérieur for a genuine "first this, then that".
Already done by then
Even without a subordinate clause, the futur antérieur says that something is already over by a future point. The futur simple says it takes place then.
Taking place or already over
À huit heures, je dînerai.
At eight I'll have dinner.
À huit heures, j'aurai dîné.
By eight I'll have had dinner.
J'aurai terminé avant midi.
I'll have finished before noon.
Dans deux ans, nous aurons remboursé le prêt.
In two years we'll have paid off the loan.
Guessing about the past
The second use has nothing to do with the future: the futur antérieur expresses a guess about something that has already happened, a plausible explanation rather than a fact. English says this with must have or probably.
Explaining after the event
Il n'est pas là – il aura oublié le rendez-vous.
He isn't here – he must have forgotten the appointment.
Elle ne répond pas, elle sera déjà partie.
She isn't answering – she must have left already.
Tu ne trouves pas tes clés ? Tu les auras laissées au bureau.
Can't find your keys? You must have left them at the office.
