We use the future perfect tense to describe an action that will be completed before another action or specific moment in the future. It helps us emphasize that something will be finished by a future deadline.
Example:
By the time you arrive, I will have finished my homework.
An action completed before another future action or moment:
<----------|------X---------X---->
now work finished you arrive
The action that will happen first uses the future perfect.
The later action usually uses the present simple.
Subject + will have + past participle + complement.
Examples:
I will have finished my homework by 8:00 p.m.
We will have written the report by Friday.
She will have completed the course before she starts her new job.
They will have arrived by the time the meeting begins.
Subject + will not have + past participle + complement.
Note: The contraction of will not is won’t.
Examples:
I won’t have finished my breakfast before the bus arrives.
You won’t have completed the project by Monday.
They will not have arrived before the event starts.
She won’t have saved enough money by the end of the year.
Will + subject + have + past participle + complement?
Short answers:
Yes, subject + will.
No, subject + won’t.
Examples:
Will she have gone home before you arrive?
Will you have made dinner by 7:00 p.m.?
Will they have eaten before the meeting begins?
Will he have finished the project by Friday?
Wh-question word + will + subject + have + past participle + complement?
Examples:
What will you have accomplished by the end of the year?
When will she have completed the course?
Where will they have travelled by the end of their trip?
Who will you have spoken to before the meeting?
Why will he have left before the event begins?
How much money will you have saved by December?
Important: We commonly use the future perfect with by, by the time, before, and by then to show the future deadline.