Use the Future Perfect for something that will be finished before a moment in the future: By 6 pm I'll have finished the report. Form: will have + past participle.
By Friday I'll have finished the report.
Look back from a future moment: by then, the action will already be done.
| Positive | I'll have finished. · She'll have left. |
|---|---|
| Negative | I won't have finished. |
| Question | Will you have finished? |
By the time you get home, I'll have cooked dinner.
Typical with by and by the time: the action is complete before that point.
In June we'll have lived here for ten years.
With state verbs and for: how long something will have lasted by then.
Words that often go with this tense. They're hints, not rules.
By the time you wake up, I _____.
Other future tenses: Future Simple (will), Future Continuous, Future Perfect Continuous.
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By is a deadline: the action happens at some point before then (Send it by Friday). Until means the situation continues all the way up to then (I'll wait until Friday).
Less often in casual speech, but it's common at work when talking about deadlines (We'll have completed the migration by June) and in exams.