Learning objectives
- Understand what the future perfect describes: an action completed before a specific point in the future
- Form the future perfect correctly using will have + past participle
- Use 'by' + a future time expression correctly with the future perfect
- Use the correct tense (present simple, not future) in a 'by the time' clause referring to the future
- Distinguish the future perfect from the future simple and the future continuous
- Form the past participle of common irregular verbs correctly
- Avoid common errors when using the future perfect
Grammar & vocabulary
Formation: will have + past participle
The future perfect is formed with will have + the past participle of the main verb, the same form for every subject. Affirmative: "I will have finished this project by next Friday." "She will have graduated by the time she turns 22." Negative: subject + will not have (won't have) + past participle — "They won't have arrived by 8 pm." Question: Will + subject + have + past participle? — "Will you have finished your homework by tonight?"
Use: an action completed before a specific future point
The future perfect describes an action that will be completed before a particular moment or another event in the future — it looks back from a point in the future at an action that will already be finished by then. Example: "By next year, I will have graduated from university." (My graduation will happen, and by the time next year arrives, it will already be in the past relative to that point.) Example: "By the time you arrive, we will have finished dinner." (Our finishing dinner will happen before your arrival.)
"By the time" + present simple, + future perfect
When a "by the time" clause refers to the future, the verb in that clause is in the present simple, NOT the future — even though the meaning is future. The future perfect is used in the other clause to show what will already be completed by then. Correct: "By the time she gets here, I will have left." Incorrect: "By the time she will get here, I will have left." This rule also applies to other time clauses referring to the future, such as those starting with "when", "before", "after" or "as soon as" — they use the present simple, not "will". Correct: "When the guests arrive, we will have already set the table."
Future perfect vs. future simple vs. future continuous
Future simple (will + base verb) describes a single future action, with no reference to another point in time — "I will call you tomorrow." Future continuous (will be + verb-ing) describes an action that will be in progress at a specific moment in the future — "At 8 pm tonight, I will be studying." (still in progress at that exact moment). Future perfect (will have + past participle) describes an action that will already be completed before a specific moment in the future — "By 8 pm tonight, I will have finished studying." (already finished by that moment). Compare all three: "I will write the report." (a simple future fact) "At 5 pm, I will be writing the report." (in progress at 5 pm) "By 5 pm, I will have written the report." (finished before or at 5 pm).
More examples with irregular past participles
"By the end of this year, she will have written three novels." (write – written) "By the time he retires, he will have taught for over thirty years." (teach – taught) "We will have driven more than 500 kilometers by the time we arrive." (drive – driven) "By next month, they will have chosen a new director." (choose – chosen) "I will have finished this book by tomorrow." (finish – finished, a regular verb).
Common mistakes
Using the future tense in a 'by the time' clause instead of the present simple — 'By the time you will arrive, we will have finished dinner' is incorrect; the correct form is 'By the time you arrive, we will have finished dinner,' since time clauses referring to the future use the present tense, not 'will'.
Forgetting 'have' after 'will' — 'I will finished my homework by 9 pm' is incorrect; the correct form is 'I will have finished my homework by 9 pm.'
Using the wrong past participle for irregular verbs — 'I will have wrote the report' is incorrect; the correct form is 'I will have written the report.'
Confusing the future perfect (a completed action) with the future continuous (an action in progress) — 'By 8 pm, I will be finishing my homework' is not correct for a completed action; the correct form is 'By 8 pm, I will have finished my homework,' while 'At 8 pm, I will be doing my homework' correctly describes an action still in progress at that exact moment.
Overusing the future perfect for a simple future action with no reference point — a single, straightforward future action only needs the future simple: 'I will call you tomorrow,' not 'I will have called you tomorrow,' unless there is a clear 'before a point in time' meaning.
Worked example — A five-year plan
Passage
"By the time I turn 25, I will have finished university and I will have found my first job. By next summer, I will have completed my final exams, and by the time I graduate, I will have written a research project on renewable energy. I also hope that by 2030, scientists will have made major breakthroughs in medicine that will improve millions of lives."
Explanation
Each "will have + past participle" verb ("will have finished", "will have found", "will have completed", "will have written", "will have made") marks an action that will already be completed at or before the future point mentioned. Notice that the time clauses use the present simple, not the future: "by the time I turn 25" (not "will turn") and "by the time I graduate" (not "will graduate") — the present simple is required in these clauses even though the whole sentence is about the future.
3 practice exercises
Exercise 1
EasyPut the verb in brackets into the future perfect. 1) By next year, she ___ (finish) her studies. 2) By the time we get home, the movie ___ (already / start). 3) I ___ (save) enough money to buy a car by the end of this year.
Show answer
1) will have finished 2) will have already started 3) will have saved.
Exercise 2
MediumChoose the correct future form (future simple, future continuous or future perfect) for each sentence. 1) At this time tomorrow, I ___ (fly) to Paris. 2) By the time you read this letter, I ___ (leave) the country. 3) I ___ (call) you as soon as I land. 4) By 2030, this company ___ (open) branches in ten countries.
Show answer
1) will be flying (future continuous — in progress at that exact moment) 2) will have left (future perfect — completed before you read it) 3) will call (future simple — a single future action) 4) will have opened (future perfect — completed by that future point).
Exercise 3
HardFind and correct the error in each sentence. 1) By the time she will arrive, we will have already left. 2) I will finished my homework by 9 pm. 3) By next month, he will have wrote a full report.
Show answer
1) 'she will arrive' → 'she arrives' (a time clause about the future uses the present simple, not 'will'). 2) 'will finished' → 'will have finished' (missing 'have'). 3) 'will have wrote' → 'will have written' (correct past participle of 'write').
3 exercices, c'est un début.
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FAQ
How do you form the future perfect in English?
The future perfect is formed with will have + the past participle of the main verb, the same form for every subject — for example, 'I will have finished', 'she will have graduated', 'they will have arrived'.
What tense is used in a 'by the time' clause that refers to the future?
Even though the meaning is future, the verb in a 'by the time' clause (and in similar time clauses with 'when', 'before', 'after' or 'as soon as') is in the present simple, not the future — for example, 'By the time she gets here, I will have left,' not 'By the time she will get here...'.
What is the difference between the future perfect and the future continuous?
The future perfect (will have + past participle) describes an action that will already be completed before a specific point in the future, such as 'By 8 pm, I will have finished studying.' The future continuous (will be + verb-ing) describes an action that will still be in progress at that exact moment, such as 'At 8 pm, I will be studying.'