The Future Perfect describes an action that will be completed before a certain moment in the future. It is almost always used with “by” + a time.
How to form the Future Perfect
| Type | Pattern | Example |
|---|---|---|
| Affirmative | subject + will have + past participle | I will have finished. · She will have left. |
| Negative | subject + will not have + past participle | They won't have arrived. |
| Question | Will + subject + have + past participle? | Will you have finished by Friday? |
When to use the Future Perfect
- An action completed before a future time: I will have finished the report by Friday.
- A milestone: In June they will have been married for 20 years.
- A confident guess about the present: It's six o'clock – they will have arrived by now.
Signal words
These words often show that the Future Perfect is needed: by, by then, by the time, by next week, by 2030, before, in two years.
Examples
- By 2030 she will have graduated.
- We will have left before you wake up.
- Will you have finished by noon?
- He won't have read the book by then.
- By the time you come, I will have cooked dinner.
- They will have built the bridge by next year.
Common mistakes
- Using will after “by the time”: By the time you will arrive → By the time you arrive.
- Confusing by (not later than) with until (up to a time, an ongoing state).
Frequently asked questions
What is the difference between “by” and “until”?
“By Friday” means not later than Friday. “Until Friday” means all the time up to Friday (I will be here until Friday).